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2,4-Dichlorophenoxyacetic acid (2,4-D), a member of the phenoxy family of herbicides is commonly used in agriculture for controlling broadleaf weeds but its uncontrolled and incoherent use has been linked to incidences of lung toxicity. The present study aimed to understand the molecular mechanisms behind the 2,4-D alone or in combination with endotoxin (lipopolysaccharide [LPS]) induced pulmonary toxicity. Blood and lung samples were collected from Swiss albino mice (n = 48) following chronic exposure to high (37 mg/kg; 1/10th of LD 50 ) and low (18.5 mg/kg; 1/20th of LD 50 ) doses of 2,4-D alone or in combination with endotoxin (80 µg/animal). Transcriptome analysis revealed Wnt Canonical signaling as one of the top dysregulated pathways in mice lung following exposure to 2,4-D with and without endotoxin (LPS) co-exposure. Global view of differentially expressed genes showed increased messenger RNA expression of Axin2 by 0.26, 2.58, 3.14, 2.59, and 2.97 folds following exposure to LPS, high dose alone or in combination with LPS and low dose alone or in combination with LPS, respectively. The microarray data were validated using quantitative polymerase chain reaction and immunohistochemistry. Furthermore, the plasma concentration of Axin2 was elevated in the high dose group as revealed by Sandwich ELISA. The data taken together suggest a role of Axin2 to activate the Canonical Wnt signaling pathway in 2,4-D and or endotoxin-induced lung damage in mice., (© 2021 Wiley Periodicals LLC.)

The current generation of carcinogenicity tests is often insufficient to predict cancer outcomes from pesticide exposures. In order to facilitate health risk assessment, The International Agency for Research on Cancer identified 10 key characteristics which are commonly exhibited by human carcinogens. The ToxTracker panel of six validated GFP-based mouse embryonic stem reporter cell lines is designed to measure a number of these carcinogenic properties namely DNA damage, oxidative stress and the unfolded protein response. Here we present an evaluation of the carcinogenic potential of the herbicides glyphosate, 2,4-D and dicamba either alone or in combination, using the ToxTracker assay system. The pesticide 2,4-D was found to be a strong inducer of oxidative stress and an unfolded protein response. Dicamba induced a mild oxidative stress response, whilst glyphosate did not elicit a positive outcome in any of the assays. The results from a mixture of the three herbicides was primarily an oxidative stress response, which was most likely due to 2,4-D with dicamba or glyphosate only playing a minor role. These findings provide initial information regarding the risk assessment of carcinogenic effects arising from exposure to a mixture of these herbicides., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Common waterhemp emerges throughout the crop growing season in the Midwestern United States, and as a result, the seedlings are exposed to a wide range of temperature regimes. Typically, 2,4-D is used in the Midwest to control winter annual broad-leaf weeds before planting soybean and in an early post-emergence application in corn and sorghum; however, the evolution of 2,4-D-resistant common waterhemp in several Midwestern states may limit the use of 2.4-D for controlling this problem weed. Moreover, temperature is one of the crucial factors affecting weed control efficacy of 2,4-D. This research investigated the effect of temperature on efficacy of 2,4-D to control 2,4-D susceptible (WHS) and -resistant (WHR) common waterhemp. Do se-response of WHS and WHR to 2,4-D was assessed at two temperature regimes, high (HT; 34/20 °C, d/n) and low (LT; 24/10 °C, d/n). Whole plant dose response study indicated an increased level of 2,4-D resistance in WHR at HT compared to LT. Additional investigation of the physiological mechanism of this response indicated that both WHS and WHR common waterhemp plants rapidly metabolized 14 C 2,4-D at HT compared to LT. In conclusion, a rapid metabolism of 2,4-D conferred increased level of resistance to 2,4-D in WHR at HT. Therefore, application of 2,4-D when temperatures are cooler can improve control of 2,4-D resistant common waterhemp.

The gut microbiota critically confers various health benefits, whereas environmental chemicals can affect its constitution and functionality thereby increasing disease risk. In the present study, we aim to evaluate the toxic effects of a wildly-used herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) on the gut microbiome and host using an occupationally relevant dose. A mouse model was used combined with metagenomic sequencing and metabolomic profiling to examine the alterations induced by subchronic low-dose 2,4-D exposure in fecal and plasma samples. The metagenomics results revealed a distinct gut microbial community with profound changes in diverse microbial pathways including urea degradation, amino acid and carbohydrate metabolism in 2,4-D-treated mice. Moreover, the metabolomics results revealed that the metabolic profiles in treatment group were differentiated from control group in both fecal and plasma samples. Toxic effects on the host of 2,4-D at an occupationally relevant dose were observed indicated by decreased acylcarnitine levels in plasma. These findings indicated that 2,4-D can cause toxicity and substantially impact the gut microbiome in mice at occupationally relevant doses, inferring that the relationship between environmental contaminants and microbiota is largely underestimated calling for more comprehensive consideration of the toxicity of occupational exposures.

The aim of this study was to evaluate the effect of time of the day and their associated climatic conditions on spray deposition of two 2,4-D formulations, as well as the influence on weed control. The experiment was installed in the field in complete randomized design. Treatments were arranged in factorial design 8 × 2, with 20 repetitions. First factor corresponded to different application time (1:00, 4:00, 7:00, 10:00, 13:00, 16:00, 19:00, and 22:00) with their respective climatic conditions. The second factor consisted of two formulations of 2,4-D applied at 776 g a.e. ha -1 (2,4-D amine and 2,4-D choline salt with Colex-D™ Technology) + glyphosate (816 g a.e. ha -1 ). There was more spray deposition when 2,4-D choline formulation was used, and such differences were more evident for applications performed under adverse climatic conditions. More spray deposition was found in applications performed at times of day with more favorable temperature and humidity of the air conditions. Only the initial control of the evaluated species was affected by the time of application.

Background and Objective: Sipahutar pineapple (Ananas comosus L.) is a indigenous of pineapple grown in Sipahutar district, North Sumatra, Indonesia. Propagation of Sipahutar pineapple that being done traditionally is less effective, because the number of seeds that produced is very limited and requires a long time. Propagation through in vitro culture is an alternative solution to solve this problem. It is necessary to add plant growth regulator (PGR) to stimulate callus formation in Sipahutar pineapple explants (Ananas comosus L.). Callus induction of pineapple from Sipahutar was carried out by PGR treatment on MS medium. The purpose of this study was to determine the effect MS medium treatment with added dichlorophenoxyacetic acid (2,4-D) and benzyl amino purin (BAP) PGR on Sipahutar pineapple callus formation (Ananas comosus L.) with light and dark treatment., Materials and Methods: This callus induction research used a completely randomized design (CRD) with 2 factors, the first factor was treatment 2,4-D (0, 1, 2) ppm. The second factor is BAP (0, 0.5, 1) ppm., Results: Nine combinations of treatments are obtained. Each combination of treatments is treated in both light and dark conditions. The parameters of this study were the percentage (%) of explants that formed callus, the time of callus formed, callus texture, callus biomass, callus surface height and callus surface area. Data were analyzed with two-way ANOVA, followed by Duncan Multiple Rate Test (DMRT)., Conclusion: The study showed that the interaction between 2,4-D and BAP significantly affected the time of callus formed but 2,4-D and BAP did not significantly affect callus biomass, callus surface height and callus surface area. All explants can form callus, except explants without the addition of 2,4-D and BAP. The callus formed on 10 days after induction (DAI) and 12 DAI with the treatment of light and dark. The color of the produced callus were white, yellowish white, greenish white, brown, brownish yellow, brownish white, brownish green, yellowish green and greenish white. The callus formed is generally compact textures, except for explants which by giving 1 ppm 2,4-D produce friable callus.

Arctium lappa L. (Burdock) is an important plant with various pharmacological effects. According to the importance of this plant, optimization of its tissue culture will lead to more investigation and application of it. The aim of this study was to develop protocols for callus induction and shoot regeneration of A.  lappa. In order to optimize of tissue culture in A. lappa, callus induction, indirect regeneration and direct regeneration were carried out in factorial experiment based on Completely Randomized Designs (CRDs). Hypocotyl and cotyledon were cultured on the Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of 2,4-Dichlorophenoxyacetic acid (2,4-D) and 6-Benzylaminopurine (BAP) for callus induction. In indirect regeneration experiment various levels of BAP and α-Naphthaleneacetic acid (NAA) and two types of explants (calli derived from cotyledon and hypocotyl) were investigated. In direct regeneration section, various levels of BAP plus 2 mg/l NAA and different explants (cotyledon, hypocotyl and bud) were compared. In both cotyledon and hypocotyl, the maximum callus induction was observed on a media containing 2 mg/l 2,4-D plus 1 mg/l BAP (100% and 76.19% respectively). The highest percentage of indirect regeneration (65%) was observed at 1 mg/l BAP plus 0.5 mg/l NAA on calli from hypocotyl. The highest percentage of direct regeneration (90.33) was observed in hypocotyl with a lateral bud explant on MS medium supplemented with 0.5 mg/l BAP plus 2 mg/l NAA. In this study, optimization of tissue culture protocol for A. lappa was carried out as a research technique, as well as technique for further exploitation of this plant.

The objective of this study was to evaluate the effects of nozzle types and 2,4-D formulations on spray deposition on different targets. Two field experiments were carried out in a completely randomized design, and treatments were arranged in a factorial scheme. Species in experiment 1 were Sumatran fleabane (Conyza sumatrensis) and Brazil pusley (Richardia brasiliensis) and in experiment 2 were soybeans (Glycine max) and Benghal dayflower (Commelina benghalensis). For both experiments, the first factor corresponded to spray nozzles with different settings (AD 110.015 - 61 and 105 L ha -1 ; AD 015-D - 75 and 146 L ha -1 ; XR 110.0202 - 200 L ha -1 ; and ADIA-D 110.02 - 208 L ha -1 ) and the second factor consisted of two formulations of 2,4-D (amine and choline). The formulation of 2,4-D choline has contained Colex-D™ Technology. Similar or higher spray deposition was observed on the leaves and artificial targets when using 2,4-D choline as compared to the 2,4-D amine formulation, and these differences in deposition were more evident for nozzles applying lower spray volumes. Deposition was more affected by nozzle type when amine formulation was used, compared to choline formulation.

It was reported that 2,4-dichlorophenoxyacetic acid (2,4-D), a commonly used herbicide and a possible endocrine disruptor, can disturb spermatogenesis, but the precise mechanism is not understood. Since 2,4-D is a weak peroxisome proliferator in hepatocytes and peroxisome proliferator-activated receptor α (PPARα) is also expressed in Leydig cells, this study aimed to investigate the link between PPARα and 2,4-D-mediated testicular dysfunction. 2,4-D (130 mg/kg/day) was administered to wild-type and Ppara-null mice for 2 weeks, and the alterations in testis and testosterone/cholesterol metabolism in Leydig cells were examined. Treatment with 2,4-D markedly decreased testicular testosterone in wild-type mice, leading to degeneration of spermatocytes and Sertoli cells. The 2,4-D decreased cholesterol levels in Leydig cells of wild-type mice through down-regulating the expression of 3-hydroxy-3-methylglutaryl coenzyme A synthase 1 and reductase, involved in de novo cholesterogenesis. However, the mRNAs encoding the important proteins involved in testosterone synthesis were unchanged by 2,4-D except for CYP17A1, indicating that exhausted cholesterol levels in the cells is a main reason for reduced testicular testosterone. Additionally, pregnancy rate and the number of pups between 2,4-D-treated wild-type male mice and untreated female mice were significantly lower compared with those between untreated couples. These phenomena were not observed in 2,4-D-treated Ppara-null males. Collectively, these results suggest a critical role for PPARα in 2,4-D-induced testicular toxicity due to disruption of cholesterol/testosterone homeostasis in Leydig cells. This study yields novel insights into the possible mechanism of testicular dysfunction and male infertility caused by 2,4-D.

Effect of exogenously applied jasmonic acid (JA) in combination with calcium and verapamil (a calcium channels blocker) on the production of flavonoids and isoflavonoids in suspension cultures of Trifolium pratense L. was investigated. The culture was cultivated in Gamborg medium with an addition of 2 mg.l(-1) of 2,4-dichlorophenoxyacetic acid and 2 mg.l(-1) of 6-benzylaminopurine, at the temperature of 25 °C, 16-hr light/8-hr dark period. The best effect of jasmonic acid on the production of flavonoids and isoflavonoids was manifested after a 24-hour application of the 50 μmol.l(-1) concentration. The maximum production of JA-induced suspension culture was observed when cells were treated with a high level of calcium (10 mmol.l(-1)). The addition of all concentrations of verapamil to JA-induced suspension culture decreased production of flavonoids and isoflavonoids.

Prior studies have shown that applications of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) to the foliage of potato plants can reduce common scab. Here field and glasshouse trials suggest that 2,4-D foliar treatments may also reduce the biologically distinct tuber disease, powdery scab. Significant correlations between suppression of common and powdery scab from the field trials suggested an interaction between the two diseases or possible additional broad spectrum mechanisms of enhanced defence against pathogen invasion provided by 2,4-D treatment.

We synthesized twenty thiazolidin-4-one derivatives, which were then characterized by standard chromatographic and spectroscopic methods. From the in vitro glucose uptake assay, two compounds behaved as insulin sensitizers, where they enhanced glucose uptake in isolated rat diaphragm. In high-carbohydrate diet-induced insulin resistant mice, these two thiazolidin-4-ones attenuated hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hypercholesterolemia, and glucose intolerance. They raised the plasma leptin but did not reverse the diabetes-induced hypoadiponectinemia. Additionally, compound 3a reduced adiposity. The test compounds were also able to reverse the disturbed liver antioxidant milieu. To conclude, these two novel thiazolidin-4-ones modulated multiple mechanisms involved in metabolic disorders, reversing insulin resistance and thus preventing the development of type-2 diabetes.

This study aims to assess effects of 96 h goldfish exposure to 1, 10 and 100 mg/L of the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), on metabolic indices and free radical process markers in white muscle of a commercial fish, the goldfish Carassius auratus L. Most oxidative stress markers and antioxidant enzymes were not affected at 2,4-D fish treatment. 2,4-D fish exposure induced the elevated levels of total (by 46% and 40%) and reduced (by 77% and 73%) glutathione in muscles of goldfish of 10 mg/L 2,4-D and recovery (after 100 mg/L of 2,4-D exposure) groups, respectively. However, in muscles of 100 mg/L 2,4-D exposed goldfish these parameters were depleted (by 47% and 64%). None of investigated parameters of protein and carbohydrate metabolisms changed in white muscles of 2,4-D exposed fish, with exception of lactate dehydrogenase activity, which was slightly (by 11-15%) elevated in muscles of goldfish exposed to 10-100 mg/L of 2,4-D, but also recovered. Thus, the short term exposure of goldfish to the selected concentrations of 2,4-D does not substantially affect their white muscle, suggesting the absence of any effect under the environmentally relevant concentrations., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

J. curcas has been studied in different countries and some interesting agronomic, pharmacological and industrial properties have been reported. More recently, it has been considered an important alternative source for biofuel production. The objective of this study was to establish a long-term method for the maintenance of calli and cell suspension cultures of the local species J. curcas and J. gossypifolia, in order to allow future studies for novel compounds with pharmaceutical or industrial applications. For this, friable calli were successfully induced from hypocotyl segments of.. curcas and J. gossypifolia that were cultured in semisolid MS media supplemented with 1.5 mg/L, and 0.5 mg/L of 2,4-D, respectively. Cell suspension cultures of J. curcas were established using 1 g of 35 and 60-day calli, in 50 mL of liquid MS media supplied with 1.5 mg/L of 2,4-D; sucrose and maltose were additionally evaluated as carbon sources. After 35 days, cell suspension cultures initiated with 35-day calli, showed greater cell growth with a maximum biomass of 194.9 g/L fresh weight, 6.59 g/L dry weight and 17.3% packed volume. The exponential phase ended at day 35 for cultures initiated with 35-day calli, and at day 21 for cultures initiated with 60-day calli. Higher biomass production was obtained with sucrose. Cell cultures were established with 35-day calli in MS media with the same 2,4-D concentration used for calli induction and 30g/L sucrose. This medium was considered optimum for the maintenance and growth of cell suspensions for both species, with sub-cultures every 20 days. The biotechnological potential for the production of bioactive compounds in these species for pharmacological, agricultural and industrial applications is being evaluated.

Black carrots contain anthocyanins possessing enhanced physiological activities. Explants of young black carrot shoots were cultured in Murashige and Skoog (MS) medium for callus initiation and were transferred to new MS medium supplemented with four different combinations of 2,4-dichlorophenoxyacetic acid and kinetin. Subsequently, the lyophilized calli and black carrot harvested from fields were subjected to ultrasound extraction with ethanol at a ratio of 1:15 (w:v). Obtained extracts were applied to various human cancer cell lines including MCF-7 SK-BR-3 and MDA-MB-231 (human breast adenocarcinomas), HT-29 (human colon adenocarcinoma), PC-3 (human prostate adenocarcinoma), Neuro 2A (Musmusculus neuroblastoma) cancer cell lines and VERO (African green monkey kidney) normal cell line by MTT assay. The highest cytotoxic activity was achieved against Neuro-2A cell lines exhibiting viability of 38-46% at 6.25 μg/ml concentration for all calli and natural extracts. However, a significantly high IC50 value of 170.13 μg/ml was attained in normal cell line VERO indicating that its natural counterpart is an ideal candidate for treatment of brain cancer without causing negative effects to normal healthy cells.

We studied the eco-toxic and carcinogenic effects of a commonly used 2,4-D acid iso-octylester herbicide on rat liver and pancreas. The rats in Group 1 were fed a standard feed and the rats in Group 2 were fed with standard feed to which was added 200 mg/kg/day 2,4-D acid iso-octylester for 16 weeks. Azaserine, 30 mg/kg/body weight, was injected into rats of Groups 3 and 4 to investigate the effects of 2,4-D acid iso-octylester on the development of neoplasms. After feeding the rats with neoplasms in Group 4 with food including 200 mg/kg/day 2,4-D acid iso-octylester for 16 weeks, an autopsy was carried out on all animals. We found that 2,4-D acid iso-octylester caused the formation of atypical cell foci (ACF) in the pancreata and livers of rats. ACF that were formed experimentally by exposure to azaserine had increased diameter, volume and number of atypical cell foci/mm(2) and mm(3) after exposure to 2,4-D acid iso-octylester. Our observations indicated that this herbicide potentially is a cancer initiator.

Conventional chemical exposure assessment relies upon measurements or estimates of chemical concentrations in environmental media, food, or products, in combination with assumptions regarding contact rates, in order to estimate external doses (ppm in air) or intake rates of chemicals (e.g., mg/kg/day ingested). A risk assessment is conducted by comparing these external or intake dose estimates to appropriate (e.g., route-specific) exposure guidance values (e.g., Reference Dose or Reference Concentration) to assess whether exposures are exceeding levels of concern. Human biomonitoring, in which concentrations of chemicals are measured in blood or urine, is being increasingly used as an alternative or complementary exposure assessment. The Biomonitoring Equivalent, which is the translation of a Reference Dose to an equivalent concentration of a compound in blood or urine, provides a parallel means to interpret biomonitoring data in order to assess whether chemical-specific exposures exceed levels of concern. This manuscript presents a side-by-side comparison of the two approaches for assessing exposures and risks for a case study compound, 2,4-dichlorophenoxyacetic acid (2,4-D). The findings from this case study indicate that the external dose-based assessments result in estimates of exposure and resulting hazard quotients that are consistently several-fold higher than those based on biomonitoring data. These comparisons support a conclusion that exposure assessments conducted as part of the registration process for 2,4-D incorporate sufficiently conservative assumptions., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The sustained release and reduced leaching of herbicides is expected for enhancing their efficacy and minimizing their pollution. For this purpose, the rice straw biochar made at a relatively low temperature (350 °C) (RS350) was used simultaneously as the carrier for incorporating herbicides besides as the soil amendment. In this way, the sustained release of herbicides acetochlor and 2,4-D was obtained in the release experiments, due to the high and reversible sorption by RS350 biochar. Besides, the RS350 biochar significantly reduced the leached amount of herbicides by 25.4%-40.7% for acetochlor, and by 30.2%-45.5% for 2,4-D, depending on the depth (50 or 100 mm) of biochar-amended soil horizon. The high retention of both herbicides in the biochar-amended topsoil makes it possible to extend their efficacy. The results suggest a potential way of using low temperature biochars to reduce the leaching of herbicides without impacting their efficacy.

The 2,4-Dichlorophenoxyacetic acid (2,4-D) was used in agriculture as an herbicide in many countries including Tunisia. The aim of this study was to evaluate the effects of 2,4-D on liver function of adult rats and their progeny. Female Wistar rats were divided into two groups: the controls and the treated rats which received 600 ppm of 2,4-D in their drinking water from the 14th day of pregnancy until day 14 after delivery. In 2,4-D group, a significant decrease in body weight of pups was noted, when compared to controls. Liver antioxidant enzyme activities, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) decreased, while malondialdehyde (MDA) levels increased in dams and pups. Moreover, plasma aminotransferases (ALT, AST), gamma glutamil transpeptidase (GGT), lactate dehydrogenase (LDH), bilirubin and albumin levels were increased significantly. The biochemical modifications were correlated with histopathological studies. We concluded that 2,4-D induced hepatotoxicity in adult and suckling rats., (Copyright © 2010 Wiley Periodicals, Inc.)

Hexagonal mesoporous silica modified with carboxylic acid (SiAc) has been obtained by reaction between chloroacetic acid and 3-aminopropyltrimethoxysilane, which was immobilized on porous material by a sol-gel process in the presence of an n-dodecylamine template. SiAc was characterized by TG, FT-IR, (29)Si NMR, (13)C NMR, SEM, surface charge density, surface area and porous diameter, which proved that the carboxylic group was chemically bonded to an inorganic structure, and the material presented a nanometric structure with spheres <50 nm and porous diameter of 10 nm. Herbicides 2,4-D and picloram were anchored on SiAc porous gel to produce the materials named SiD and SiPi, respectively. The controlled release of picloram from the SiAc was less than that of 2,4-D. After 26 days of releasing, 4.43 × 10(-5) mol L(-1) of picloram was delivered by SiPi, and 5.0 × 10(-5) L(-1) was released from the SiD in 30 days.

Several types of pesticides, such as organophosphates, phenoxyacetic acid, and carbamate have a high risk of affecting human health, causing allergic rhinitis and bronchial asthma-like diseases. We used our long-term sensitization method and a local lymph node assay to examine the allergic reactions caused by several types of pesticides. BALB/c mice were topically sensitized (9 times in 3 weeks), then challenged dermally or intratracheally with 2,4-D, BRP, or furathiocarb. One day post-challenge, the mice were processed to obtain biologic materials for use in assays of total IgE levels in serum and bronchoalveolar lavage fluid (BALF); differential cell counts and chemokine levels in BALF; lymphocyte counts and surface antigen expression on B-cells within regional lymph nodes (LNs); and, ex situ cytokine production by cells from these LNs. 2,4-D-induced immune responses characteristic of immediate-type respiratory reactions, as evidenced by increased total IgE levels in both serum and BALF; an influx of eosinophils, neutrophils, and chemokines (MCP-1, eotaxin, and MIP-1beta) in BALF; increased surface antigen expression on B-cells IgE and MHC class II production) in both auricular and the lung-associated LNs; and increased Th2 cytokine production (IL-4, IL-5, IL-10, and IL-13) in both auricular and the lung-associated LN cells. In contrast, BRP and furathiocarb treatment yielded, at most, non-significant increases in all respiratory allergic parameters. BRP and furathiocarb induced marked proliferation of MHC Class II-positive B-cells and Th1 cytokines (IL-2, TNF-alpha, and IFN-gamma) in only auricular LN cells. These results suggest that 2,4-D is a respiratory allergen and BRP and furathiocarb are contact allergens. As our protocol detected classified allergic responses to low-molecular-weight chemicals, it thus may be useful for detecting environmental chemical-related allergy.

Carboxymethylcellulose (CMC) gel was used for encapsulating anionic herbicide 2,4-D for its controlled release. The slower release rate of 2,4-D in water and soil was obtained by adding in the gel formulation some modified bentonites, which were prepared by intercalating inorganic or organic cations in interlayers of Na(+)-saturated bentonite. The higher encapsulation efficiencies of 2,4-D were observed on the bentonite/CMC gel formulations due to the sorption of 2,4-D on modified bentonites. The time taken for 50% of 2,4-D to be released in water, t(50), showed a variation (8.8-19.8 h) for these gel formulations, the largest value corresponding to the formulation incorporated with hydroxy-iron intercalated bentonite that has the highest sorption capacity to 2,4-D. The gel formulations could also control the release of 2,4-D when applied to a thin soil layer and demonstrated potential to reduce leaching of such anionic herbicides in soil.

Background/aims: Plant growth regulators are considered to leave minimal amounts of remnants and therefore cause no significant side effects in humans. In this study, we aimed to investigate the hormonal and histopathological effects of 4-chlorophenoxy acetic acid (4-CPA), a commonly used plant growth regulator, on the gonadal functions of rats., Methods: The study was implemented on 64 Wistar albino rats (20 days old). Forty-eight rats received 4-CPA every day until 50 days of age. The rats were randomized into 4 groups (a control group and three 4-CPA groups with doses of 25, 50 and 100 mg/kg/day); each group was further divided into males and females, making a total of 8 groups. The levels of FSH, LH, testosterone, estradiol, leptin, inhibin-B and neuropeptide-Y were measured. Histopathological examination of the testes and ductus deferens in male rats, and ovaries and uterus of female rats (caspase-3 and -9 immunoreactivity) was performed., Results: Although hormone levels were similar between the groups, rats that received 4-CPA showed significantly higher degrees of apoptosis compared to the control group (p < 0.001) and increased doses of 4-CPA were directly correlated with the amount of apoptosis (p < 0.001)., Conclusion: 4-CPA induced apoptosis in the gonads of rats without concurrent changes in plasma hormone levels.

Bioluminescence-based bacterial biosensors are often reported as reliable and efficient tools for risk assessment and environmental monitoring. However, there are few data comparing the metabolism of genetically engineered strains to the corresponding wild type. A pollutant-degrading bacterium capable of mineralising 2,4-dichlorophenoxyacetic acid (2,4-D), Burkholderia sp. strain RASC c2, was genetically engineered to produce light constitutively and tested for assessing the main causes of biodegradation constraint affected by growth rates, toxicity, bioavailability and metal speciation in complex environments. This research focuses on such aspects by characterizing two pollutant-degrading isolates, the wild type and the genetically engineered biosensor (lux-marked). Degradation and growth rates of both isolates were assessed with different concentrations of 2,4-D as the sole carbon source. Kinetic rates were affected by initial concentration of substrate and isolates showed distinct growth rates at different 2,4-D concentrations. Toxic effects of zinc and copper were also comparatively assessed using a dehydrogenase assay and light output. The isolates were sensitive to both metals and at similar EC(50) values. Therefore, bioluminescence response of the lux-marked isolate accurately reflected the toxic response of the parental organism towards zinc and copper, making it an ideal test-organism for assessing toxicity in the context of pollutant mineralization.

The effects of some plant growth regulators (PGRs), 2,3,5-triiodobenzoic acid (TIBA), Naphthaleneacetic acid (NAA) and 2,4-Dichlorofenoxyacetic acid (2,4-D), at sublethal concentrations on antioxidant defense system [glutathione peroxidases (GPx), reduced glutathione (GSH), glutathione reductase (GR), glutathione-S-transferase (GST) and catalase (CAT)], immune potential enzymes [adenosine deaminase (ADA) and myeloperoxidase (MPO)], and lipid peroxidation content [Malondialdehyde, (MDA)] were investigated in lung and speen tissues of rats. Sprague-Dawley albino rats were exposed to 0, 50, or 100 ppm (parts per million) TIBA, NAA, or 2,4-D in drinking water ad libitum for 25 days continuously. According to the results, MDA concentration significantly increased in the tissues treated with 100 ppm dosage of NAA or 2,4-D without any change in the tissues of rats treated with both dosage of TIBA. The GSH depletion in the spleen tissue of rats treated with both the dosage of NAA and 2,4-D were found to be significant. Also, GSH level in the spleen was significantly reduced with 100 ppm of 2,4-D and NAA. The activity of antioxidant enzymes were also seriously affected by PGRs; GPx significantly decreased in the lung of rats treated with both dosages of the PGRs, whereas GPx activity in the spleen were significantly increased with 100 ppm dosage of 2,4-D and NAA. On the other hand, CAT activity significantly decreased in the lung of rats treated with both dosages of NAA, 100 ppm of 2,4-D and 50 ppm of TIBA, and also in the spleen treated with 50 ppm NAA and 2,4-D. The ancillary enzyme GR activity significantly decreased in the spleen with both doses of the PGRs, also in the lung treated with both dosages of 2,4-D, 50 ppm of NAA and 100 ppm of TIBA. The drug metabolizing enzyme GST activity significantly reduced in the lung of rats treated with both dosages of the PGRs and also in the spleen treated with 100 ppm dosage of 2,4-D and TIBA and 50 ppm of NAA. Meanwhile, immune potential enzyme MPO activity significantly increased in the spleen of rats treated with both doses of NAA and TIBA whereas ADA activity significantly decreased in the spleen of rats treated with 100 ppm dose of NAA and TIBA. The observations presented led us to conclude that the administrations of subacute NAA, 2,4-D, and TIBA promote MDA content, inhibit the antioxidative defense system and activate or inhibit immune potential enzymes in the rat's spleen and lung tissues. These data suggest that PGRs produced substantial organ toxicity in the lung and spleen during the period of a 25-day subacute exposure.

Background: Both chronic and acute ethanol consumption increase transdermal penetration of topically applied xenobiotics. The mechanisms by which this enhancement occurs are unknown. We hypothesized that either the vasodilatory effects of ethanol or its ability to disrupt the lipid bilayer via lipid peroxidation, may be contributing to the increased transdermal absorption observed in alcohol consuming animals., Methods: Male Wistar rats were gavaged with 1.5, 3, 4.3, 6 or 10 g/kg ethanol or saline control or were treated with either the vasoconstrictor epinephrine or with the vasodilator prilocaine. Dermal blood flow, transepidermal water loss (TEWL), and skin moisture were non-invasively measured. Transdermal penetration was then determined for four xenobiotics (paraquat, dimethyl formamide (DMF), 2,4-dichlorophenoxyacetic acid (2,4-D) and N,N-diethyl-m-toluamide (DEET)). Lipid peroxidation was also determined by monitoring the formation of malondialdehyde., Results: Dermal blood flow increased by approximately 27% (p<0.05), TEWL increased 1.12+/-0.2-fold while skin lipid peroxidation increased 1.4-fold (p<0.05) 2h after gavage with 10 g/kg alcohol. Transdermal penetration of paraquat was increased by prilocaine (ER=2.1+/-0.4, p<0.05), but the absorption of DEET, 2,4-D and DMF were not influenced by greater blood flow. Reducing dermal blood flow with epinephrine did not cause any significant changes in transdermal penetration., Conclusions: Vasodilation triggered by a single episode of ethanol ingestion is not responsible for the observed increase in transdermal absorption. Ethanol induced changes in lipid peroxidation and TEWL demonstrate that drinking alcohol induces transdermal absorption of xenobiotics.

Moisturizing lotions can be an effective treatment for occupationally induced dry skin. These compounds are designed to be hygroscopic and retain water to keep the stratum corneum hydrated, while at the same time enhancing the horny layer to prevent increases in transepidermal water loss (TEWL). Skin hydration levels, however, are known to influence barrier properties. The purpose of this work was to compare skin moisture levels induced by four commercially available moisturizing lotions with their capacity as transdermal penetration enhancers using the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) as a model chemical. Further, the effect of moisturizing the skin after washing with sodium lauryl sulfate (SLS) on transdermal absorption was determined. Skin moisture levels were also measured noninvasively and were correlated to penetration enhancement. Hairless mouse skin was pretreated with commercially available moisturizing lotions either with or without SLS washing and in vitro permeability studies were performed with the herbicide 2,4-D. The data demonstrate that pretreatment with three of the four lotions tested increased the transdermal absorption of 2,4-D as evidenced by cumulative penetration or faster lag times (p < 0.05). Skin moisture levels correlated with the penetration enhancement capabilities of the lotion. Washing the skin with 5% SDS increased the transdermal absorption of 2,4-D (p < 0.05) and application of moisturizing lotions increased the absorption further. In summary moisturizing lotions may influence transdermal penetration of the skin, with the more effective moisturizers having a greater effect on 2,4-D absorption.

With growing use of synthetic adjuvants in modern agriculture, their impacts on the environment are being questioned. In a search for an environmentally safe phyto-adjuvant, we have investigated natural glycosidic saponin for delivery of agromaterials through plant cuticle membranes. Four saponin preparations from Quillaja saponaria bark (QE), obtained from Sigma-Aldrich, and Balanites aegyptiaca fruit mesocarp (ME), kernel (KE), and root (RE), isolated and characterized in our laboratory, were used for testing the delivery of [14C]-2,4-dichlorophenoxyacetic acid (2,4-D) across isolated intact astomatous adaxial Citrus grandis leaf cuticle membranes (CMs). The results showed that both Q. saponaria and B. aegyptiaca saponin preparations enhanced delivery of 2,4-D through CMs. Among the saponin preparations, ME exhibited a significantly higher level of delivery of 2,4-D with a concentration effect (2% being the highest). Transmission electron microscope (TEM) and dynamic light scattering (DLS) characterization of these saponin preparations in aqueous solution clearly demonstrated the formation of nanoscale vesicles. Various possibilities for a natural amphiphatic phyto-saponin as a delivery adjuvant through CMs are discussed.

A Mg/Al layered double hydroxide (LDH) was intercalated with the anionic herbicides 2,4-D, MCPA, and picloram by using three different methodologies: (i) direct synthesis (DS), (ii) regeneration (RE), and (iii) ion exchange (IE). The resulting complexes were characterized and assayed by batch release and column leaching tests, aiming at the controlled release of these herbicides. All the tested LDH-herbicide complexes displayed similar slow herbicide release properties in water, although the IE method seemed to result in complexes with a greater fraction of herbicide in a readily available form. Apparently, the LDH-herbicide complexes released most of the active ingredient present in the complexes at the end of the batch release experiment. This was attributed to the replacement of the intercalated herbicide by carbonate and hydroxyl anions from the aqueous solution. Compared to the free herbicides, the application of the three LDH-herbicide complexes (RE) to soil columns resulted in reduction in the maximum herbicide concentration in leachates and led to the retardation of herbicide leaching through the soil. All LDH-herbicide complexes presented an herbicidal efficacy similar to that of the free (technical) herbicides. Our results indicated the potential applicability of LDHs as supports for the preparation of slow release formulations of acid herbicides such as 2,4-D, MCPA, or picloram.

Objectives: To determine the effect of skin thickness on the percutaneous penetration and distribution of test compounds with varying physicochemical properties using in vitro systems. Studies were carried out in accordance with OECD guidelines on skin absorption tests., Methods: Percutaneous penetration of caffeine (log P -0.01), testosterone (log P 3.32), propoxur (log P 1.52) (finite dose in ethanol to water vehicle ratio) and butoxyethanol (log P 0.83) (undiluted finite dose or as an infinite dose 50% [v/v] aqueous solution) through skin of varying thicknesses under occluded conditions was measured using flow through cells for 8-24 h. Saline (adjusted to pH 7.4) was used as receptor fluid, with BSA added for studies with testosterone and propoxur. Following exposure, the remaining surface dose was removed by swabbing and the skin digested prior to scintillation counting., Results: The maximum flux of caffeine was increased with decreasing skin thickness, although these differences were found to be non-significant. The presence of caffeine in the skin membrane was not altered by skin thickness. Maximum flux and cumulative dose absorbed of testosterone and butoxyethanol (in both finite and infinite doses) were markedly reduced with full thickness (about 1 mm thick) skin compared with split thickness skin (about 0.5 mm). Maximum flux of propoxur (dissolved in 60% ethanol) was clearly higher through skin of 0.71 mm than through skin of 1.36 mm, but no difference was found between 0.56 and 0.71 mm. The proportion of propoxur present in the membrane after 24 h increased significantly over the complete range of thicknesses tested (0.56-1.36 mm)., Conclusions: A complex relationship exists between skin thickness, lipophilicity and percutaneous penetration and distribution. This has implications for risk assessment studies and for the validation of models with data from different sources.

The accumulation of 2,4-dichlorophenoxyacetic acid (2,4-D) and its metabolite 2,4-dichlorophenol (2,4-DCP) in the kidneys of rats was investigated. Male and female Sprague-Dawley rats were given 2,4-D in drinking water and food for 30 days. Group A (control group) was fed a normal diet, Group B was fed 50 ppm 2,4-D in 15 g food, Group C received 100 ppm 2,4-D in 15 g food, Group D received 25 ppm 2,4-D in 15 ml drinking water and Group E was given 50 ppm 2,4-D in 15 ml of drinking water. Levels of 2,4-D and 2,4-DCP in kidneys were determined using high performance liquid chromatography (HPLC). It was observed that at low doses of 2,4-D, the metabolite, 2,4-DCP found in the kidneys.

2,4-dichlorophenoxyacetic acid and monosodium methanearsonate are often sold in commercial mixtures. Bioconcentration studies have been performed for each of these herbicides individually, but little information exists concerning long-term exposure to a mixture of these herbicides. The following study examined the uptake of arsenic in crawfish after long-term exposure to this mixture, and the health risks associated with consumption of these crawfish. Bioconcentration and depuration experiments using a 50:50 by concentration mixture of the two herbicides, with and without surfactant, were performed to quantify how much arsenic is concentrated in the edible tissue of the crawfish. Of the three tissues (muscle, gill, and hepatopancreas) sampled hepatopancreas bioconcentrated the highest amount of arsenic. Surfactant significantly reduced this uptake but did not affect bioconcentration of arsenic into other tissues. Surfactant had no effect on depuration of arsenic from any of the tissues. Cooking lowered hepatopancreatic arsenic content, possibly as a result of structural changes in the hepatopancreas. Assessment of the human health risk associated with consuming these crawfish showed an exposure dose at the high end of consumption that was approximately twice the reference dose for arsenic. Cancer risks were averaged at approximately 7 extra tumors in a population of 10,000 and 6 extra tumors in a population of 10,000 resulting from a lifetime consumption of crawfish exposed to the herbicide mixture without and with surfactant, respectively.

This study determined alterations to bone marrow B-cell populations after in vivo exposure to a mixture containing the herbicides 3,4-dichloropropionanilide (propanil) and 2,4-dichlorophenoxyacetic acid (2,4-D) and compared them to the effects of exposure to the individual herbicides. Propanil and 2,4-D are postemergent herbicides that are sold commercially as a mixture. The individual herbicides or the mixture containing propanil and 2,4-D were administered intraperitoneally to C57Bl/6 female mice at doses from 50 to 200 mg herbicide/kg body weight. The mixtures were given in a 1:1 ratio. Flow cytometric analysis was performed to quantitate bone marrow B-cell populations at 1, 2, 7, and 14d posttreatment. Mixture treatment decreased pre-B and immunoglobulin (Ig) M(+) B-cell populations at all doses by 2 d postexposure. The cell populations were still decreased at 7d posttreatment. In contrast, exposure to the individual herbicides only caused decreases in the pre-B and IgM(+) B-cell populations 7d after exposure to the high doses. Previous studies have demonstrated that corticosterone levels are increased by exposure to propanil. Therefore, the glucocorticoid hormone, corticosterone, was investigated as a possible mediator of cell loss in the bone marrow. Treatment with the glucocorticoid receptor antagonist, RU 486, however, did not prevent cell loss in the bone marrow of mice exposed to the mixture of propanil and 2,4-D. This study demonstrates that pre-B and IgM(+) B-cell populations are decreased after exposure to propanil, 2,4-D, or the mixture containing propanil and 2,4-D. Exposure to the mixture had greater toxic effects than the individual herbicides on bone marrow pre-B and IgM(+) B-cell populations, emphasizing the need to study mixture interactions.

In cultured Bright Yellow-2 tobacco (Nicotiana tabacum) cells, the depletion of 2,4-dichlorophenoxyacetic acid (2,4-D) in the culture medium induces amyloplast development. This differentiation also includes a decrease in cell multiplication, and an increase in cell size. These changes were primarily triggered by the depletion of 2,4-D, and accelerated by the addition of benzyladenine (BA). Three cDNAs were identified whose transcript levels are specifically increased during differentiation of starch-storing cells using the differential display method, and designated as starch-storing cell induced genes (SCI genes). One of these cDNAs, SCI2 encodes a 285 amino acids long protein with a KH RNA-binding domain. A database search revealed that this protein showed similarity to respective domains of mammalian quaking proteins. 2,4-D addition, which can convert starch-storing cells into dividing cells, to starch-storing BY-2 cells, immediately decreases the SCI2 transcript level, suggesting that SCI2 may have some role in starch-storing cell differentiation in BY-2 cells.

The scientific evidence in humans and animals relevant to cancer risks, neurologic disease, reproductive risks, and immunotoxicity of 2,4-D was reviewed. Despite several thorough in vitro and in vivo animal studies, no experimental evidence exists supporting the theory that 2,4-D or any of its salts and esters damages DNA under physiologic conditions. Studies in rodents demonstrate a lack of oncogenic or carcinogenic effects following a lifetime dietary administration of 2,4-D. Epidemiologic studies provide scant evidence that exposure to 2,4-D is associated with soft tissue sarcoma, non-Hodgkin's lymphoma, Hodgkin's disease, or any other cancer. Overall, the available evidence from epidemiologic studies is not adequate to conclude that any form of cancer is causally associated with 2,4-D exposure. There is no human evidence of adverse reproductive outcomes related to 2,4-D. The available data from animal studies of acute, subchronic, and chronic exposure to 2,4-D, its salts, and esters show an unequivocal lack of systemic toxicity at doses that do not exceed renal clearance mechanisms. There is no evidence that 2,4-D in any of its forms activates or transforms the immune system in animals at any dose. At high doses, 2,4-D damages the liver and kidney and irritates mucous membranes. Although myotonia and alterations in gait and behavioral indices are observed after overwhelming doses of 2,4-D, alterations in the neurologic system of experimental animals are not observed with the administration of doses in the microgram/kg/day range. It is unlikely that 2,4-D has any neurotoxic potential at doses below those required to induce systemic toxicity.

Male Vietnam veterans have repeatedly expressed concern that exposure to herbicides in Vietnam may have caused birth defects in their offspring. The second most used herbicide was a mixture of 2,4-D and picloram called Agent White. This study is an investigation into the possible male-mediated reproductive toxicology of this herbicide. Male rats were gavaged for 5 days per week for 9 weeks with a mixture of 2,4-D and picloram called Tordon 75D(R) (the Australian derivative of Agent White). Three doses were tested; the high dose was considered the maximum tolerated dose. Each male was mated with two untreated females during weeks 2 and 3, 4 and 5, and 8 and 9 of treatment, and with four untreated females after an 11-week recovery period. Negative controls were males dosed with distilled water, and positive controls were males dosed with cyclophosphamide at 5.1 mg/kg/day. All mated females were killed on day 20 of gestation, and the fetuses were weighed and examined for either structural malformations or skeletal development. Litter size, fetal weight, and malformation rate were all unaffected by treatment. The cyclophosphamide positive controls showed the expected large increase in postimplantation loss. In general, within the limitations of the power of the study, the results did not show any evidence that exposure to a herbicide formulation containing 2,4-D and picloram is likely to cause male-mediated birth defects or other adverse reproductive outcomes.

The second most used herbicide in the Vietnam war was Agent White, which contained the active components 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-amino-3,5,6-trichloropicolinic acid (picloram). The herbicide formulation Tordon 75D is similar in terms of its active components to Agent White and is currently used by the agricultural industry in Australia. As part of an investigation into the possible adverse effects of this herbicide on male reproductive performance, groups of five male rats were gavaged 5 days a week for 9 weeks with either 0.125 ml/kg (low dose), 0.25 ml/kg (middle dose), or 0.5 ml/kg (high dose) Tordon 75D or water (controls). The high dose corresponded to 150 mg/kg body weight 2,4-D and 37.5 mg/kg picloram acid equivalents. At the end of the treatment period, the testes were collected, weighed, and examined histologically and blood samples were taken to determine serum testosterone. Groups of high dose animals were also examined after 1, 2, and 4 weeks treatment. The 9 weeks treatment with Tordon 75D caused severe reduction in testicular weight in some high dose animals. Histologically, the small testes showed shrunken tubules with germ cell depletion. This damage was still evident in some rats following a 21 weeks recovery period suggesting that the testicular damage was permanent. Testicular damage was not due to endocrine disruption as there were no significant differences in the serum concentration of testosterone in control animals compared to Tordon 75D-treated animals. Blood levels associated with the high dose were determined in a separate study and were much higher than those likely to be obtained by occupational exposure to this herbicide.

Hydrotalcite-like inorganic layers of Zn-Al, a host containing an organic moiety, 2,4-dichlorophenoxy-acetate, as a guest, was prepared by the spontaneous self-assembly method from an aqueous solution for the formation of a new layered organic-inorganic hybrid nanocomposite material. In this synthesis, the host- and guest-forming species were simultaneously included in the mother liquor, aged, and separated. Various Zn/Al ratios (R = 2, 3, and 4), concentrations of 2,4-dichlorophenoxyacetic acid (0.03-0.1 M), and pH (7 and 10) were studied to optimize the formation of the layered nancomposite. It was found that the optimum conditions for the formation of the nanocomposite were R = 4, pH 7, and concentration of 2,4-dichlorophenoxyacetic acid = 0.08 M. X-ray diffraction shows that this sample affords a nanolayered structure with a basal spacing of 24.6 A.

Consecutive spectral analyses of ultraweak photon emission from sweet potato showing a defense response were conducted to observe the process of physiological transition. The spectrum showed a drastic transition from 2 to 10 h after inoculation with Fusarium oxysporum, during which the emission intensity increased slowly. The spectrum was stable from 10 to 36 h after inoculation, whereas the emission intensity peaked approximately 20 h after inoculation. A change in the physiological state connected with the synthesis of defense-related substances is suggested as contributing to this phenomenon. The spectral transition was also detected in sweet potato treated with growth hormone or exposed to alternating temperature, although with an extremely weak emission intensity. This spectral analysis of ultraweak photon emission can be used as a new means for identifying the physiological state.

An experimental study on non-inbred rats indicated the toxic effect of a single dose of the herbicide 2,4-dichlorophenoxyacetic acid amine salt in a dose of 240 mg/kg on phagocytic defense processes appeared as phasic changes in the concentration of peripheral leukocytes, in the microbicidal, absorptive, and oxidative activity of polymorphonuclear leukocytes and peritoneal macrophages till day 60 of the follow-up. The course administration of vitamin E produced a beneficial effect on most study indices under aftereffect of a toxicant, which was mostly manifested in the blood levels of leukocytes and in the microbicidal capacity of phagocytes.

Peroxisome proliferators are non-mutagenic carcinogens in the liver of rodents, acting both as initiators and promoters. The National Toxicology Program (NTP) conducted a study of several peroxisome proliferators (PPs), including Wyeth (WY)-14643 as a prototypical PP and 2,4-dichlorophenoxyacetic acid (2,4-D) as a weak PP, in Sprague-Dawley rats. B6C3F1 mice, and Syrian hamsters. In the kidney, an unusual change was observed in the outer stripe of the outer medulla, especially in rats treated with 2,4-D or WY-14643. This change was characterized by foci of tubules that were partially or completely lined by basophilic epithelial cells with decreased cytoplasm and high nuclear density. Changes typical of chronic nephropathy such as interstitial fibrosis or basement membrane thickening were not associated with these foci. Results of immunohistochemical staining for catalase and cytochrome P-450 4A in the kidney indicated increased staining intensity in renal tubular epithelial cells primarily in the region where the affected tubules were observed: however, the altered cells were negative for both immunohistochemical markers. Ultrastructurally, affected cells had long brush borders typical of the P3 tubule segment. The most distinguishing ultrastructural change was a decreased amount of electronlucent cytoplasm that contained few differentiated organelles and, in particular, a prominent reduced volume and number of mitochondria; changes in peroxisomes were not apparent. In addition to the lesion in rats, mice treated with the highest dose of 2,4-D, but not WY-14643, manifested similar renal tubular changes as seen by light microscopy. Neither chemical induced renal tubular lesions in hamsters. Hepatocellular changes characteristic of PPs were present in all 3 species treated with WY-14643, but not 2,4-D. These results indicate that the rat is the species most sensitive to the nephrotoxic effects of PPs and there is a site specificity to this toxicity related to areas of PP-related enzyme induction. Although 2,4-D is considered a weak PP for the liver, it was the most effective at inducing renal lesions, indicating that the toxic potency of various PPs will depend on the target organ.

Although, the mechanism of 2,4-dichlorophenoxyacetic acid (2,4-D) neurotoxicity remains unknown, the monoaminergic system appears to mediate some of its effects in rats as we previously reported. In this study; we examined the 2,4-D effects on locomotor activity, circling behavior and monoamine levels after the injection into the basal ganglia of male adult rats. These effects were compared with those induced after selective lesions of dopaminergic neurons with 6-hydroxydopamine (6-OHDA). 2,4-D-injected into one striatum (100 microg/rat) produced a marked depression in locomotor activity and elicited a moderate circling towards the ipsilateral side at 6 and 24 h postinjection. These behavioral changes were accompanied by a decrease and an increase of serotonin (5-HT) and homovanillic acid (HVA) levels, respectively. 2,4-D administration (100 microg/rat) into the nucleus accumbens, induced similar behavioral and neurochemical patterns to the intrastriatal 2,4-D injection, although rats did not present notorious turning. When 2,4-D was injected into one medial forebrain bundle (MFB, 50 microg/rat), animals presented ipsilateral circling, while locomotor activity was unchanged at 3 and 7 days post-injection. These last rats also exhibited diminished levels of striatal 5-HT, dopamine (DA) and their metabolites without changes in the substantia nigra (SN). Animals sacrificed 3 and 7 days after a 6-OHDA injection into one of the MFB, presented progressive depletion of dopamine in striatum and SN. 2,4-D as well as 6-OHDA-treated rats into one of the MFB were challenged with low dose (0.05 mg/kg s.c.) of apomorphine (only at 7 days post-injection) to evaluate a possible DA-receptor supersensitivity. Only 6-OHDA treated rats showing a vigorous contralateral rotation activity. These results indicate that 2,4-D induced a regionally-specific neurotoxicity in the basal ganglia of rats. The neurotoxic effects of 2,4-D on basal ganglia by interacting with the monoaminergic system depended not only on the exact location of the 2,4-D injection, but also on the dose and time period of post-injection. Toxicity produced by 2,4-D appears to be different in monoaminergic terminals, axonal fibers, and cell bodies.

The fate of 2,4-dichlorophenoxyacetic acid (2,4-D) applied foliarly as the 2-ethylhexyl ester (EHE) to wheat and potatoes, to the soil as the dimethylamine (DMA) salt under apple tree canopies, and preplant as the free acid for wheat, lettuce, and radish was studied to evaluate metabolic pathways. Crop fractions analyzed for (14)C residues included wheat forage, straw, and grain; potato vine and tubers; and apple fruit. The primary metabolic pathway for foliar application in wheat is ester hydrolysis followed by the formation of base-labile 2,4-D conjugates. A less significant pathway for 2,4-D in wheat was ring hydroxylation to give NIH-shift products 2,5-dichloro-4-hydroxyphenoxyacetic acid (4-OH-2,5-D), 4-OH-2,3-D, and 5-OH-2,4-D both free and as acid-labile conjugates. The primary metabolic pathway in potato was again ester hydrolysis. 2,4-D acid was further transformed to 4-chlorophenoxyacetic acid and 4-OH-2,5-D. For the soil applications, (14)C residues in the crops were low, and characterization of the (14)C residues indicated association with or incorporation into the biochemical matrix of the tissue. The degradative pathways observed in wheat are similar to those characterized in other intact plant studies but differ from those in studies in wheat cell suspension culture in that no amino acid conjugates were observed.

Female CD-1 mice were exposed to a commercial amine formulation of 2,4-dichlorophenoxyacetic acid (2,4-D) on days 6-16 of gestation in drinking water at concentrations ranging from 0 to 1.0% of the formulated product, equivalent to approximately 0-650 mg/kg/d expressed as the amine derivative. The effect of 2,4-D on urethan-induced pulmonary adenoma formation was evaluated in female offspring 19 w after birth. Urethan-induced sleeping times observed following ip injection of 1.5 mg urethan/g bw 7 w after birth were not altered by 2,4-D (p = 0.10), indicating that 2,4-D did not affect the rate of urethan elimination. 2,4-D exposure did not affect the number of tumors produced (p = 0.58), but did reduce the mean tumor diameter in the highest dose group (p < 0.01). This minor antineoplastic activity of 2,4-D may be related, in part, to inhibitory effects of 2,4-D on various enzymatic or metabolic pathways, essential for cellular growth and tissue development. Since exposure to 2,4-D during pregnancy had little impact of tumor production, it is unlikely that persistent alteration to developing immune cells involved in the cell-mediated immunosurveillance mechanisms occurred. The subtle alteration in tumor size and the mild impairment of growth in the offspring were observed almost exclusively in the highest treatment group. Since this level of exposure is well in excess of those associated with normal application of 2,4-D, the hazard to non-target mammalian populations appears minimal.

Objective: To investigate the clinical effects and to determine the 2,4-dichlorophenoxyacetic acid plasma concentrations after a dose of twice the reported LD50 (100 mg/kg) was administered orally to dogs. Investigation included electromyographic evaluations and biochemical parameter determinations, as well as observable clinical signs., Methods: Six beagle dogs were administered 2,4-dichlorophenoxyacetic acid 200 mg/kg orally. Dogs were monitored for the development of clinical signs and were anesthetized at 24 hours for needle electromyography. Blood was collected pre- and 24-hours postadministration. Plasma was analyzed for total and unbound 2,4-dichlorophenoxyacetic acid by high-performance liquid chromatography with fluorescence detection. Serum was submitted for clinical chemistry parameter analysis. Statistical analyses of the chemistry parameters were performed using paired t-tests., Results: All 6 dogs survived after oral administration of twice the reported LD50. Clinical signs observed were vomiting in 33% and diarrhea in 100% of the dogs. No gait abnormalities were seen in awake dogs. Electromyographic findings revealed predominantly insertional myotonia with 1 dog having spontaneous fibrillations. Decreases from baseline measurements were seen in serum calcium, potassium, and total bilirubin. The mean total and unbound plasma 2,4-dichlorophenoxyacetic acid concentrations were 511 mg/L and 129 mg/L, respectively., Conclusions: This study demonstrates that the beagle dog is less sensitive to the acute effects of 2,4-dichlorophenoxyacetic acid than previously reported. The main clinical effects seen after oral administration of twice the reported LD50 were vomiting and diarrhea. Total and unbound plasma 2,4-dichlorophenoxyacetic acid concentrations may be a useful indicator of toxicity.

In experiments on 124 noninbred white rats weighing 180-200 g the influence of the intragastric administration of amino of 2,4-dichlorophenoxyacetic acid in doses of 2.0 and 20 mg/kg daily on the characteristics of their mononuclear phagocyte system was studied. The study revealed a decrease in the number of monocytic precursors in the marrow, an increase in their capacity for colony formation, the inhibited cell function on the periphery of the system simultaneously with the enhancement of oxidizing processes. The metabolic activation of cells was accompanied by their functional insufficiency, which led to the activation of monocytopoiesis and the increased migration of monocytes to peripheral blood.

The acute toxicity of 2,4-dichlorophenoxyacetic acid (2,4-D), a herbicide, was studied in chicks dosed with 100, 300, 500, or 600 mg 2,4-D/kg BW, by the oral route. Clinical, laboratory, and histopathological methods were used as indicators of toxicity. After acute exposure, the herbicide decreased motor activity and induced muscular weakness and motor incoordination; decreased weight gain; increased serum creatine kinase (CK) and alkaline phosphatase (AP) activities and serum uric acid (UA), creatinine (CR), and total proteins (TP) levels; and did not change serum aspartate aminotransferase (AST) or alanine aminotransferase (ALT) activities. These changes were time- and dose-dependent and reversible. The LD50 (lethal dose 50%) calculated for oral 2,4-D in chicks was 420 mg/kg BW (385 to 483). Chromatographic analysis of the serum of the intoxicated chicks showed the presence of the herbicide; the amount found was dose- and time-dependent, increasing from 2 to 8 h after exposure and decreasing afterwards. Histopathological post-mortem studies conducted on intoxicated chicks showed hepatic (vacuolar degeneration of the hepatocytes), renal (tubular nephrosis), and intestinal (hemorrhagic) lesions. Taken together, the observed alterations mainly reflected kidney and muscle tissue damage, although hepatic toxicity may also have occurred after acute 2,4-D intoxication.

The commercial formulations of 3 commonly used herbicides (the amine salt of 2,4-dichlorophenoxyacetic acid, trifluralin and triallate) were evaluated for effects on immune function in male Fisher 344 rats. The herbicides were prepared in an olive oil vehicle and administered by oral gavage twice weekly for 28 d at the following doses: 10.0 mg 2,4-D/kg; 17.5 mg trifluralin/kg; 5.0 mg triallate/kg/treatment. Normal body weight and organ/body weight ratios indicated the rats tolerated the herbicide treatments without difficulty. Exposure to 2,4-D did not alter lymphocyte blastogenesis, 1 gm antibody production (anti-sheep red blood cell), lymphocyte cell surface marker expression or phagocytic function of peritoneal macrophages. Trifluralin acted as a weak mitogen, but impaired T-lymphocyte blastogenesis induced by phytohemagglutinin and concanavalin A. Other immunological measurements were unaffected by trifluralin exposure. Triallate exposure reduced peritoneal macrophage phagocytosis by 33%, showed weak mitogenic properties and impaired T-lymphocyte blastogenesis in the presence of phytohemagglutin. Triallate also increased the anti-sheep red blood cell response expressed/spleen by 43%, a phenomenon suggestive of a compensatory response to minimize the impact on overall immune function. The changes in lymphocyte or macrophage function due to the herbicide treatments were not associated with changes in lymphocyte cell surface antigen expression.

The fetotoxic effect of 2,4-dichlorophenoxyacetic acid (2,4-D) was investigated. Histological and histochemical changes in the liver of newborn, jung and adult rats exposed to the herbicide from the prenatal period to the end of an experiment were evaluated. The experiment used 90 male and female, Wistar, aged to 10 weeks rats, divided into two groups: I-control-30 and II-60 animals which received the water solution of 2,4-D acid sodium salt in a daily dose of 250 mg/kg b.w. It was given with drinking water every day. The animals were sacrificed after 24 hours, 4, 6, and 10 weeks of the experiment. The results obtained showed that the administration of 2,4-D acid to rats in the prenatal and postnatal period, in a dose inducing subacute intoxication leads to histological and histochemical changes in the liver. The observed changes indicate disorders in energetic processes in hepatocytes and are morphological exponents of detoxicative processes there. They are most intensified with newborn rats. It suggest also, the pregnants ought not to work with 2,4-D and should avoid any contact with herbicides belongs to the 2,4-dichlorophenoxyacetic acid group.

The role of biliary elimination in the metabolic disposition of 2,4-D was evaluated in male and female Sprague-Dawley rats, B6C3F1 mice, and Syrian hamsters. Following cannulation of the bile duct, an intragastric (ig) dose of 2,4-D (200 mg/kg) was administered and bile was collected at 30- or 60-min intervals for up to 6 h. Bile flow rates were constant in rats, increased in mice, and decreased in hamsters throughout the collection periods. Total recovery of radioactivity was greatest in male mice (about 7% of administered dose over 4 h). Female mice and rats of both sexes excreted about 3% over the same interval and male and female hamsters about 1%. About 71-88% of the activity in bile was parent compound. The glycine conjugate of 2,4-D was found in bile from mice, rats, and hamsters and the taurine conjugate in bile from mice. The only sex-dependent difference in the metabolite profile was in mice. Male mice excreted twice as much glycine conjugate as female mice. An additional minor metabolite (4-7%) was present in rat and mouse bile. This was tentatively identified as 2,4-D-glucuronide based on its hydrolysis by beta-glucuronidase. One more very minor metabolite (3%) was detected in rat bile but was not characterized due to its lability. The results of this study indicate that there are species-dependent differences in the biliary elimination of 2,4-D but not sex-dependent differences.