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Nitrite and nitrate have been traditionally used for the preservation of meat products because of the effective antimicrobial action of nitrite against Clostridium botulinum, the outgrowth of its spores as well as other bacteria. However, the use of nitrite and nitrate has been questioned in last half century due to the possible generation of N-nitrosamines through reaction of nitrite with secondary amines. Nitrite replacement strategies began in the 70s addressing these issues and instigated searches for natural alternatives to nitrate and nitrite, or for natural sources of nitrite and nitrate such as vegetable extracts. These alternatives have been considered by producers and consumers as an attractive practice even though they may also have some risks. This manuscript reviews and discusses the chemistry, safety, and regulatory considerations in the use of nitrite and nitrate from natural origin for the preservation of meat products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Kuanxiong Aerosol (KA) has been used in patients with angina pectoris (AP) attacks for many years, this systematic review and meta-analysis aims to evaluate the clinical efficacy and safety of KA versus nitrates in the treatment of AP., Methods: Seven databases (PubMed, EMBASE, CENTRAL, CNKI, VIP, CBM and Wanfang) were searched from inception to November 2019 to include randomized controlled trials (RCTs) that compare the efficacy and safety of KA with nitrates on the treatment of AP. And two reviewers independently assessed the risk of bias., Result: A total of 12 RCTs were eventually included, involving 2001 patients. Compared with the Nitrates group, the KA group showed great significant improvement on the 3-min [relative risk (RR) = 1.12, 95% confidence interval (CI) (1.03,1.23), P < .05;11 studies,1875 patients] and 5-min [RR = 1.05, 95%CI (1.01,1.08), P < 0.05; 11 studies,1875 patients] angina remission rates, the incidence of adverse reactions [RR = 0.42,95% CI (0.33,0.54), P < 0.00001; 8 studies, 1350 patients], endothelin(ET) [SMD = -0.40, 95%CI (-0.74,-0.07), P < 0.05; 2 studies, 143 patients] and c-reactive protein (CRP) [SMD = -0.58, 95%CI (-0.87,-0.30), P < 0.00001;2 studies, 200 patients],but no significant improvement on electrocardiogram efficacy [RR = 1.03, 95%CI (0.98,1.10), P = 0.26;11 studies, 1549 patients], nitric oxide (NO) [SMD = -0.08, 95%CI (-0.61,0.45), P = 0.76;2 studies, 143 patients]., Conclusion: The clinical use of KA is effective and safe on the treatment of AP, which appears to be better than nitrates in terms of efficiency, adverse reactions, endothelial function and inflammatory response. Nevertheless, due to some limitations in the sample size and quality of the included studies, more high-quality RCTs were still needed for further verification., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Groundwater quality investigations were carried out in one of the urban parts of south India for fluoride and nitrate contaminations, with special focus on human health risk assessment for the rapidly growing and increasingly industrialized Coimbatore City. Twenty-five groundwater samples were collected and analyzed for physico-chemical parameters (EC, pH, TDS, Ca 2+ , Mg 2+ , Na + , K + , Cl - , SO 4 2- , HCO 3 - , PO 4 3- , NO 3 - , and F - ) and the piper diagram characterized 60% of them as Ca-Mg-Cl type. Analysis of fluoride (0.1 to 2.4 mg/l) shows that 32% of the groundwater samples contain F - over the permissible limit, affecting a region of 122.10 km 2 . Nitrate (0.1 to 148 mg/l) is over the permissible limit in 44% of the groundwater samples spread over an area of 429.43 km 2 . The total hazard indices (THI) of non-carcinogenic risk for children (0.21 to 4.83), women (0.14 to 3.35), and men (0.12 to 2.90) shows some of the THI values are above the permissible limit of the US Environmental Protection Agency. The THI-based non-carcinogenic risks are 60%, 52%, and 48% for children, women, and men. This investigation suggests higher health risk for children and also recommends that proper management plan should be adopted to improve the drinking water quality in this region in order to avoid major health issues in the near future.

Background: Low-income and minority communities often face disproportionately high pollutant exposures. The lead crisis in Flint, Michigan, has sparked concern about broader socioeconomic disparities in exposures to drinking water contaminants. Nitrate is commonly found in drinking water, especially in agricultural regions, and epidemiological evidence suggests elevated risk of cancer and birth defects at levels below U.S. EPA's drinking water standard (10 mg/L NO 3 -N). However, there have been no nationwide assessments of socioeconomic disparities in exposures to nitrate or other contaminants in U.S. drinking water. The goals of this study are to identify determinants of nitrate concentrations in U.S. community water systems (CWSs) and to evaluate disparities related to wealth or race/ethnicity., Methods: We compiled nitrate data from 39,466 U.S. CWSs for 2010-2014. We used EPA's Safe Drinking Water Information System (SDWIS) to compile CWS characteristics and linked this information with both city- and county-level demographic data gathered from the U.S. Census Bureau. After applying multiple imputation methods to address censored nitrate concentration data, we conducted mixed-effects multivariable regression analyses at national and regional scales., Results: 5.6 million Americans are served by a CWS that had an average nitrate concentration ≥ 5 mg/L NO 3 -N between 2010 and 2014. Extent of agricultural land use and reliance on groundwater sources were significantly associated with nitrate. The percent of Hispanic residents served by each system was significantly associated with nitrate even after accounting for county-level cropland and livestock production, and CWSs in the top quartile of percent Hispanic residents exceeded 5 mg/L nearly three times as often as CWSs serving the lowest quartile. By contrast, the percent of residents living in poverty and percent African American residents were both inversely associated with nitrate., Conclusions: Epidemiological evidence for health effects associated with drinking water above 5 mg/L NO 3 -N raises concerns about increased risk for the 5.6 million Americans served by public water supplies with average nitrate concentrations above this level. The associations we observed between nitrate concentrations and proportions of Hispanic residents support the need for improved efforts to assist vulnerable communities in addressing contamination and protecting source waters. Future studies can extend our methods to evaluate disparities in exposures to other contaminants and links to health effects.

Groundwater is the most important natural resource which cannot be optimally used and sustained unless its quality is properly assessed. In the present study, the spatial and temporal variations in physicochemical quality parameters of groundwater of Araniar River Basin, India were analyzed to determine its suitability for drinking purpose through development of drinking water quality index (DWQI) maps of the post- and pre-monsoon periods. The suitability for drinking purpose was evaluated by comparing the physicochemical parameters of groundwater in the study area with drinking water standards prescribed by the World Health Organization (WHO) and Bureau of Indian Standards (BIS). Interpretation of physicochemical data revealed that groundwater in the basin was slightly alkaline. The cations such as sodium (Na(+)) and potassium (K(+)) and anions such as bicarbonate (HCO3 (-)) and chloride (Cl(-)) exceeded the permissible limits of drinking water standards (WHO and BIS) in certain pockets in the northeastern part of the basin during the pre-monsoon period. The higher total dissolved solids (TDS) concentration was observed in the northeastern part of the basin, and the parameters such as calcium (Ca(2+)), magnesium (Mg(2+)), sulfate (SO4 (2-)), nitrate (NO3 (-)), and fluoride (F(-)) were within the limits in both the seasons. The hydrogeochemical evaluation of groundwater of the basin demonstrated with the Piper trilinear diagram indicated that the groundwater samples of the area were of Ca(2+)-Mg(2+)-Cl(-)-SO4 (2-), Ca(2+)-Mg(2+)-HCO3 (-) and Na(+)-K(+)-Cl(-)-SO4 (2-) types during the post-monsoon period and Ca(2+)-Mg(2+)-Cl(-)-SO4 (2-), Na(+)-K(+)-Cl(-)-SO4 (2-) and Ca(2+)-Mg(2+)-HCO3 (-) types during the pre-monsoon period. The DWQI maps for the basin revealed that 90.24 and 73.46% of the basin area possess good quality drinking water during the post- and pre-monsoon seasons, respectively.

Purpose: The aim of this paper was to develop a new recreational water quality index (RWQI) as a tool to ensure the health of swimmers and to take practical decisions., Methods: RWQI was elaborated with epidemiological data, and we carried out an exhaustive study of the different guidelines for recreational waters proposed by different organisations around the world. Different parameters were chosen, considering, as a priority, the swimmer's contact and the possibility of ingestion of water during the recreational activity. Furthermore, rating curves were established for pH, chemical oxygen demand, nitrate, phosphate, detergents, enterococci, total coliforms, faecal coliforms and Escherichia coli., Results and Conclusions: The index was applied to the data set on water quality of the Potrero de los Funes River (San Luis, Argentina), generated during 2 years (2009-2010). Following the RWQI values classification, most of the Potrero de los Funes water samples fell in the good quality range during the study period.

The development of Reference Materials for Nutrients in Seawater (RMNS) has been in progress since 1993. When RMNS were produced for nitrate, silicate, and phosphate, their initial homogeneities were as low as 0.1 to 0.2% in samples of high-nutrient seawater, such as deep water from the Pacific Ocean. The relative standard uncertainties associated with instability during long-term (4.8 years) storage were approximately 0.2, 0.2, and 0.4% for nitrate, silicate, and phosphate, respectively. No instability was observed for 1.9 to 6.4 years based on the ISO Guide 35:2006 criteria; however, the relative standard uncertainties associated with instability during long-term storage were larger than the initial homogeneities of RMNS. RMNS produced by state-of-the-art techniques are currently available for global use to improve the comparability of nutrients data in the open ocean and, as discussed here, are reliable candidates to be used for certified reference materials.

The objectives of this study were to (1) examine the relationship between nitrate levels in public water supplies and risk of death from brain cancer and (2) determine whether calcium (Ca) and magnesium (Mg) levels in drinking water might modify the influence of nitrates on development of brain cancer. A matched cancer case-control study was used to investigate the relationship between the risk of death from brain cancer and exposure to nitrates in drinking water in Taiwan. All brain cancer deaths of Taiwan residents from 2003 through 2008 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to cancer cases by gender, year of birth, and year of death. Information on the levels of nitrate-nitrogen (NO₃-N), Ca, and Mg in drinking water was obtained from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cancer cases and controls was presumed to be the source of the subject's NO₃-N, Ca, and Mg exposure via drinking water. Relative to individuals whose NO₃-N exposure level was <0.38 ppm, the adjusted OR (95% CI) for brain cancer occurrence was 1.04 (0.85-1.27) for individuals who resided in municipalities served by drinking water with a NO₃-N exposure ≥ 0.38 ppm. No marked effect modification was observed due to Ca and Mg intake via drinking water on brain cancer occurrence.

Since the Second World War the consumer behaviour in developed countries changed drastically. Primarily there existed the demand for sufficient food after a period of starvation, afterwards the desire for higher quality was arising, whereas today most people ask for safe and healthy food with high quality. Therefore a united approach comprising consistent standards, sound science and robust controls is required to ensure consumers' health and to maintain consumers' confidence and satisfaction. Chemical analysis along the whole food chain downstream (tracking) from primary production to the consumer and upstream (tracing) from the consumer to primary production is an important prerequisite to ensure food safety and quality. In this frame the focus of the following paper is the "chemical safety of meat and meat products" taking into account inorganic as well as organic residues and contaminants, the use of nitrite in meat products, the incidence of veterinary drugs, as well as a Failure Mode and Effect Analysis (FMEA) system assessing (prioritizing) vulnerable food chain steps to decrease or eliminate vulnerability.

Nitrite and nitrate are used as additives in ham industry to provide colour, taste and protect against clostridia. The classical colorimetric methods widely used to determine nitrite and nitrate are laborious, suffer from matrix interferences and involve the use of toxic cadmium. The use of chromatography is potentially attractive since it is more rapid, sensitive, selective and provides reliable and accurate results. A rapid and cost-effective RP-HPLC method with diode array detector was optimized and validated for quantification of nitrites and nitrates in ham. The chromatographic separation was achieved using a HyPurity C18, 5 microm chromatographic column and gradient elution with 0.01 M n-octylamine and 5mM tetrabutylammonium hydrogenosulphate to pH 6.5. The determinations were performed in the linear range of 0.0125-10.0mg/L for nitrite and 0.0300-12.5 g/L for nitrate. The detection limits were 0.019 and 0.050 mg/kg, respectively. The reliability of the method in terms of precision and accuracy was evaluated. Coefficients of variation lower than 2.89% and 5.47% were obtained for nitrite and nitrate, respectively (n=6). Recoveries of residual nitrite/nitrate ranged between 93.6% and 104.3%. Analysis of cooked and dried ham samples was performed, and the results obtained were in agreement with reference procedures.

Is nitrate harmful to humans? Are the current limits for nitrate concentration in drinking water justified by science? There is substantial disagreement among scientists over the interpretation of evidence on the issue. There are two main health issues: the linkage between nitrate and (i) infant methaemoglobinaemia, also known as blue baby syndrome, and (ii) cancers of the digestive tract. The evidence for nitrate as a cause of these serious diseases remains controversial. On one hand there is evidence that shows there is no clear association between nitrate in drinking water and the two main health issues with which it has been linked, and there is even evidence emerging of a possible benefit of nitrate in cardiovascular health. There is also evidence of nitrate intake giving protection against infections such as gastroenteritis. Some scientists suggest that there is sufficient evidence for increasing the permitted concentration of nitrate in drinking water without increasing risks to human health. However, subgroups within a population may be more susceptible than others to the adverse health effects of nitrate. Moreover, individuals with increased rates of endogenous formation of carcinogenic N-nitroso compounds are likely to be susceptible to the development of cancers in the digestive system. Given the lack of consensus, there is an urgent need for a comprehensive, independent study to determine whether the current nitrate limit for drinking water is scientifically justified or whether it could safely be raised.

Nitrite and nitrate represent the final products of nitric oxide (NO) oxidation pathways, and their hematic concentrations are frequently assessed as an index of systemic NO production. However, their intake with food can influence their levels. Nitrite and nitrate could have a role by producing NO, because nitrite can release NO after reaction with deoxyhemoglobin and dietary nitrate can be reduced substantially to nitrite by commensal bacteria in the oral cavity. Different methods have been applied for nitrite/nitrate detection, with the most commonly used being the spectrophotometric assay based on the Griess reagent. However, a reference methodology for these determinations is still missing and many possible interferences have been reported. This chapter assesses how different experimental conditions can influence the results when detecting nitrite and nitrate in human plasma by the Griess assay and provides a simple method characterized by high reproducibility and minimized interferences by plasma constituents.

Certified reference materials (CRMs) are an essential part of the quality assurance (QA) necessary for the reliable analytical measurement of nutrients in seawater. The CRMs currently available for these analyses are not matrix matched to marine samples. QUASIMEME routinely produces test materials for the nutrients in seawater and nutrients in estuarine water and low-salinity open water Laboratory Performance Studies (LPS) that are both homogeneous and stable. QUASIMEME, in conjunction with Eurofins Scientific, Denmark have produced two reference materials (RMs). The homogeneity testing and preliminary stability studies were carried out by QUASIMEME, and the results are presented in this article. Participants of the QUASIMEME LPS who demonstrated satisfactory long-term performance for the analysis of nutrients in seawater and nutrients in estuarine water and low-salinity open water were invited to take part in the certification exercise. Twenty laboratories returned data, a summary of which is also presented. The certification and long-term stability testing and additional data analysis were carried out by Eurofins Scientific, Denmark, and are outwith the scope of this article and not reported here. Eurofins Scientific, Denmark have marketed these RMs as part of their range of VKI Reference Materials (further information is available from eurofins@eurofins.dk).

Intensive agriculture, characterized by high inputs, has serious implications on the environment. Monitoring and evaluation of projects aiming at designing, testing and applying more sustainable practices require instruments to asses agronomic as well as environmental performance. Guidelines for Good Agricultural Practice (GAP) or Good Farming Practice (GFP) define sustainable practices but give limited insight into their environmental performance. Agri-environmental indicators (AEIs) provide information on environmental as well as agronomic performance, which allows them to serve as analytical instruments in research and provide thresholds for legislation purposes. Effective AEIs are quantifiable and scientifically sound, relevant, acceptable to target groups, easy to interpret and cost-effective. This paper discusses application of four AEIs for nitrogen (N) management in three Dutch research projects: 'De Marke', 'Cows and Opportunities' and 'Farming with a future'. 'De Marke' applied Nitrogen Surplus and Groundwater Nitrate Concentration in the design and testing of environmentally sound dairy systems. 'Cows and Opportunities', testing and disseminating dairy systems designed at 'De Marke', mainly applied Nitrogen Surplus, while 'Farming with a future' used Nitrogen Surplus, Groundwater Nitrate Concentration and Residual Mineral Soil Nitrogen to support arable farmers in complying with Dutch legislation (MINAS). Nitrogen Surplus is quantifiable, appealing and easy to interpret, but lacks scientific soundness or a good relationship with groundwater quality. Nitrogen Use Efficiency is sensitive to changes in management, while Residual Mineral Soil Nitrogen is appealing and cheap, but has difficulties in scaling. Groundwater Nitrate Concentration lacks clear rules for sampling, is labor consuming, expensive and mainly used in combination with other indicators. AEIs enhanced improvements in N management by facilitating (i) definition of project goals, (ii) design of desired systems, (iii) evaluation of applied systems and (iv) improving effective communication. AEI applications in other countries show a similar pattern as found in The Netherlands. Limitations to AEI application relate to inconsistencies between different indicators, heterogeneity of soil characteristics and linkages of N, carbon and water management. AEIs should be applied in an integrated evaluation, at a scale that reflects the farm's spatial variability. Simple AEIs like Nitrogen Surplus should be supported by other indicators and/or model calculations. The paper concludes that AEIs proved their value in design, implementation and testing of farming systems, but they should be used with care, always keeping in mind that indicators are simplifications of complex and variable processes.

A study was carried out in Pettavaithalai area to evaluate the current status of physico-chemical contaminants and their sources in groundwater. Groundwater samples collected from pettavaithalai area in 15 different stations were analyzed every alternative months over a period of two years from August 2000 to June 2002. A sugar mill is situated at the heart of the study area. Three profiles (profile A, B and C) were selected based on the direction in which the sugar mill effluent flows. In each profile five samples were collected from five different station at a regular distance of about 1 Km. The physico-chemical parameters such as pH, EC TDS, TH, NO3, SO4, PO4, Na, K, Ca, Mg, DO, BOD and COD have been analyzed. The results showed that among the three profiles, many of the estimated physico-chemical parameters of profile C were very high when compared to profile B and A which indicates the poor quality of the groundwater around this area.

Perambalur is the most backward district in the state of Tamil Nadu (India). It has ten unions, of which Thirumanur union has historical importance and is blessed with fertile lands. Thirumanur union has Kollidam river and Pullambadi canal as rich sources of water for irrigation. Thirumanur union has large number of Chozha temples at various places like Thirumalapadi, Periyamanai, Kamarasavalli, Thoothur, Senapathimudikondan, Kandaradhitham, Keelapalur and Melapalur. Thirumanur union being the south end union of Perambalur district, has Trichy district and Tanjore district as its neighbours. Thirumanur union has an area of 64 hectare, of which 48 hectare is under cultivating land. This union has maximum number of thirty-six villages. Though most of the villages use river water as their major source of drinking, they also use groundwater as their other source. Lot of work has been done and published already on the groundwater quality of many villages in other different unions of the Perambalur district. But in the Thirumanur union, there was need to undertake the study to assess the drinking water quality in the region. Hence, ten villages of Thirumanur union were selected, where the people use groundwater for drinking, and the water samples were subjected to systematic analysis. The depth of the bore wells varied from 100-200 feet. The values obtained for different parameters were compared with the standard values given by ISI / ICMR / WHO and the variations were notable for the parameters like nitrate and total hardness for few samples. Therefore, a medical survey was carried out to study the harmful effects on the society due to these two parameters at the villages-Keelapazhur, Palanganatham and Venganur.

Fluoride concentrations in surface and ground water samples were determined in eight villages of Prakasham district in India. Thirty-eight samples were collected and analysed for fluoride content along with pH, electrical conductivity, total dissolved solids (TDS), total hardness, total alkalinity, chlorides (C1), sulfates (SO2-) and nitrates (NO ). Fluoride concentrations in surface and ground water samples of these villages varied between 0.5 and 9.0 mg/L. Groundwater samples contained high concentrations of fluorides compared to open well and pond water samples, which could be a major source of fluoride in water since the geological formation of this area consists of fluorite and fluoropatite. From the data, it is evident that the population in the study area is severely affected by fluorosis. Dental and skeletal fluorosis and deformation of bones in children as well as adults were observed in the study area indicating the consequences of excess fluoride concentration. Fluoride concentrations showed good correlation with TDS concentrations (R2 of 0.61) compared to other physico-chemical parameters [EC (R2 - 0.36), nitrate (R - 0.24), total hardness (R - 0.12), chloride (R2 - 0.06) and sulfate (R2 - 4 x 10(-6))].

A 2-year field experiment was conducted in an Ochric Aquic Cambosols on a 1-ha field with rotation of winter wheat-summer corn located in Fengqiu County in North China Plain from 1 October 1998 to 30 September 2000 to quantify water balance and evaluate soil water loss by deep drainage and nitrate loss by leaching out of the root zone under the current agricultural practices. Considerable deep drainage was found especially in 1999-2000, during which period up to 273.9 mm of water, accounting for 60.6% of total amount of irrigation and 24.7% of total surface input (rainfall+irrigation), was lost by deep drainage. Even in both wheat cropping seasons when total amount of surface input was less than total actual evapotranspiration, 84.0 and 121.3 mm water was lost by drainage in 1999 and 2000, respectively. Soil NO3(-)-N was transported to deeper soil layers during the growing seasons and considerable amount of NO3(-)-N accumulated at 170 cm soil layer (the bottom of root zone) during the September-October period (the harvest time of summer corn) every year. About 28.6 kg N ha-1 was lost by leaching out of the root zone in 1998-1999 and 81.8 kg N ha-1 in 1999-2000, accounting for 5.9% and 15.7% of total nitrogen (N) inputs, respectively. The significant deep drainage and nitrate leaching loss were attributed to excessive and inappropriate irrigation and nitrogen (N) fertilization, which may result in severe groundwater pollution if current agricultural managements are not changed.

In recent years, nitrate (NO3) contamination of groundwater has become a growing concern for people in rural areas in North China Plain (NCP) where groundwater is used as drinking water. The objective of this study was to evaluate groundwater resource level, to determine groundwater quality and to assess the risk of NO3 pollution in groundwater in Quzhou County in the NCP. Ordinary Kriging (OK) method was used to analyze the spatial variability of shallow groundwater level, groundwater electrical conductivity (EC) and NO3-N concentrations, and Indictor Kriging (IK) method was used to analyze the data with NO3-N concentrations equal or greater than the groundwater NO3 pollution threshold (20 mg L(-1)). The results indicated that groundwater level averaged 9.81 m, a level 6 m lower than in 1990. The spatial correlation distances for groundwater level, EC and NO3-N concentration were 21.93, 2.19 and 3.55 km, respectively. The contour map showed that shallow groundwater level areas extended from north to south across the County. Groundwater EC was above 3 dS m(-1) in the most part of the northern county. Groundwater NO3 pollution (NO3-N> or =20 mg L(-1)) mainly occurred in the County Seat areas due to wastewater irrigation and excessive fertilizer leaching from agricultural fields. At Henantuang town, besides suburban of the County Seat, groundwater was also contaminated by NO3 shown by the map generated using the IK method, which was not reflected in the map generated using the OK method. The map generated using the OK method could not reflect correctly the groundwater NO3 pollution status. The IK method is useful to assess the risk of NO3 pollution by giving the conditional probability of NO3 concentration exceeding the threshold value. It is suggested that risk assessment of NO3 pollution is useful for better managing groundwater resource, preventing soil salinization and minimizing NO3 pollution in groundwater.

Published data on nitrate (NO3-) toxicity to freshwater and marine animals are reviewed. New data on nitrate toxicity to the freshwater invertebrates Eulimnogammarus toletanus, Echinogammarus echinosetosus and Hydropsyche exocellata are also presented. The main toxic action of nitrate is due to the conversion of oxygen-carrying pigments to forms that are incapable of carrying oxygen. Nitrate toxicity to aquatic animals increases with increasing nitrate concentrations and exposure times. In contrast, nitrate toxicity may decrease with increasing body size, water salinity, and environmental adaptation. Freshwater animals appear to be more sensitive to nitrate than marine animals. A nitrate concentration of 10 mg NO3-N/l (USA federal maximum level for drinking water) can adversely affect, at least during long-term exposures, freshwater invertebrates (E. toletanus, E. echinosetosus, Cheumatopsyche pettiti, Hydropsyche occidentalis), fishes (Oncorhynchus mykiss, Oncorhynchus tshawytscha, Salmo clarki), and amphibians (Pseudacris triseriata, Rana pipiens, Rana temporaria, Bufo bufo). Safe levels below this nitrate concentration are recommended to protect sensitive freshwater animals from nitrate pollution. Furthermore, a maximum level of 2 mg NO3-N/l would be appropriate for protecting the most sensitive freshwater species. In the case of marine animals, a maximum level of 20 mg NO3-N/l may in general be acceptable. However, early developmental stages of some marine invertebrates, that are well adapted to low nitrate concentrations, may be so susceptible to nitrate as sensitive freshwater invertebrates.

Five methods for estimating maximum daily and annual nitrate (NO3) and suspended sediment loads using periodic sampling of varying intensities were compared to actual loads calculated from intensive stormflow and baseflow sampling from small, forested watersheds in north central West Virginia to determine if the less intensive sampling methods were accurate and could be utilized in TMDL development. There were no significant differences between the annual NO3 load estimates using non-intensive sampling methods and the actual NO3 loads. However, maximum daily NO3 loads were estimated less accurately than annual loads. The ability to estimate baseline NO3 loads fairly accurately with non-intensive concentration data is attributed to the small fluctuation in NO3 concentrations over flow and time, particularly during storms. By contrast, suspended sediment exports determined by any of the non-intensive methods varied significantly and widely from and compared poorly to the actual exports for both daily and annual methods. Weekly sampling better approximated actual annual exports, but there were no significant statistical differences among weekly, monthly, and quarterly estimates. Suspended sediment concentrations varied widely within and among storm events, so that accurate estimates of total annual or maximum daily loads could not be obtained from infrequent sampling.

The content of nitrites and nitrates in whole milk powder in different regions of Poland was studied. The results obtained depended both on the factory from which the samples originated and on the season of the year. In 34.2% of the samples there was a very low level of nitrates and nitrites (below acceptable level for whole milk powder served to production of modified milk and modified infant formulas). In 64.1% of the samples the level was in accordance with the national standards and in 1.7% of the samples slightly over the limit. 99.2% of the samples were in accordance with the foreign standards.

Mechanistic data, when available, have long been considered in risk assessment, such as in the development of the nitrate RfD based on effects in a sensitive group (infants). Recent advances in biology and risk assessment methods have led to a tremendous increase in the use of mechanistic data in risk assessment. Toxicokinetic data can improve extrapolation from animals to humans and characterization of human variability. This is done by the development of improved tissue dosimetry, by the use of uncertainty factors based on chemical-specific data, and in the development of physiologically based pharmacokinetic (PBPK) models. The development of the boron RfD illustrates the use of chemical-specific data in the improved choice of uncertainty factors. The draft cancer guidelines of the U.S. Environmental Protection Agency emphasize the use of mode of action data. The first choice under the guidelines is to use a chemical-specific, biologically based dose-response (BBDR) model. In the absence of a BBDR model, mode of action data are used to determine whether low-dose extrapolation is done using a linear or nonlinear (margin of exposure) approach. Considerations involved in evaluating a hypothesized mode of action are illustrated using 1,3-dichloropropene, and use of a BBDR model is illustrated using formaldehyde. Recent developments in molecular biology, including transgenic animals, microarrays, and the characterization of genetic polymorphisms, have significant potential for improving risk assessments, although further methods development is needed. Overall, use of mechanistic data has significant potential for reducing the uncertainty in assessments, while at the same time highlighting the areas of uncertainty.

Quantification of nitric oxide in vivo is difficult because of its short half-life. Instead the oxidised products, nitrite and nitrate, are commonly used as indices of nitric oxide generation. We describe here a simple method for the measurement of nitrite and nitrate in plasma using high performance capillary electrophoresis. Plasma standard curves gave regression coefficients of 0.98 for nitrite and 0.99 for nitrate with an intra-assay coefficient of variance of 4.6% for 50 microM nitrite (n = 10) and 1.2% for 50 microM nitrate (n = 10). The assay allows measurement of nitrite and nitrate in a single analysis requiring minimal sample preparation, and with the sensitivity to detect both basal and physiological changes in plasma nitrite and nitrate.

The results of the investigations conducted have shown that most milk samples analyzed contained from 2 to 55.2 mg/l nitrates (P50 = 27.2 mg/l), dried milk and dry milk mixtures contained from 56.5 to 91.0 mg/kg nitrates (P50 = 72.9 mg/kg). The amount of nitrates detected in most products prepared at special milk centers for child nutrition did not exceed the mean level of nitrates in the whole milk. However, 12% of milk samples and 6% of dry milk mixtures contained significantly higher levels of nitrates. A conclusion has been made on the necessity of testing and regulation of nitrate content in the milk and milk products for child nutrition.

The paper outlines a methodological approach to measurement of sale levels of acute and chronic chemical exposure in the toxicological experiment by using the well-known and proposed techniques of mathematical simulation of time-effect, dose-effect, and time-dose relationships and after-transition to the models of dose-status relationships while making an integral diagnostic evaluation of the body status. It is shown that it is possible to construct the diagnostic scales that differentiate the conditions of physiological normal status, good and bad adaptation, mild, moderate, and severe intoxication. By using organophosphorus pesticides, such as ciodrin and aphos, and lead nitrate as an example, the author considers if the models can be used in the sanitary standardization of xenobiotics.

The subjects of the study was determination of the residues of pesticides: lindane, metoxychlor and chlorphenvinphos, nitrates, nitrites, ammonium ions, sulphates, chlorides and urea in surface waters and underground waters in the southeastern part of the Province of Szczecin in 1983-1988. The certain pesticides and urea in none of determined samples of waters were present. The concentrations of nitrates, ammonium and chlorides below the permitted value have been. Nitrites in surface waters and in underground waters in 48 per cent and 82 percent of the samples have been respectively.

Maximal permissible amounts of nitrates in vegetables and potatoes in Poland are proposed. These food products were divided into four groups according to their ability of accumulation of these substances. Moreover, a group of vegetables from special raising plots was isolated, they would be used for feeding small children, patients, and elderly subjects which would have a declared higher health quality.

A quantitative colorimetric method for the determination of nitrate and nitrite in cheese has been subjected to collaborative study. The method includes clarification of an aqueous extract of cheese with zinc hydroxide, reduction of nitrate to nitrite via a spongy cadmium collumn (the nitrite originally present is unaltered), diazotization of sulfanilic acid with the nitrite, and coupling with 1-naphthylamine hydrochloride to form a pink azo dye whose absorbance is measured at 522 nm. The spectrophotometric responses are compared to a standard curve. In samples containing both nitrate and nitrite, nitrate is determined by difference. A standard deviation of 5.5 was obtained (5 of 6 collaborators) when a cheese sample spiked with 276 ppm sodium nitrate was analyzed by the method. The method has been adopted as official first action.