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Human health risk assessments of exposures to non-carcinogenic occupational and environmental toxicants have mostly been undertaken using the Hazard Quotient (HQ) approach, which largely ignores variabilities in both exposures and associated adverse health outcomes, unlike probabilistic approaches. Chlorpyrifos is a neurotoxic insecticide that is commonly applied by farmers in Ghana with limited research on associated health risks among applicators. The objective of this study was to assess health risks associated with chlorpyrifos exposure among applicators on rice farms in Ghana, using advanced probabilistic approaches that incorporate variability in both exposure doses and adverse response doses obtained from human epidemiological studies. Urine samples obtained from the applicators were analyzed for 3,5,6-trichloro-2-pyridinol (TCP)from which Absorbed Daily Dose (ADD) and Lifetime Average Daily Dose (LADD) levels of chlorpyrifos were estimated. The scientific literature was searched to identify human epidemiological data from studies that have reported chlorpyrifos adverse effects and their corresponding exposure levels. Equivalent ADD and LADD of chlorpyrifos were estimated from the human epidemiological data to obtain chlorpyrifos Toxicant Sensitivity Distributions (TSDs). Using the applicators' chlorpyrifos dose distribution and TSDs, adverse health risks among the applicators were characterized using the probabilistic approaches, Overall Risk Probability (ORP) and Monte Carlo Simulation (MCS). The probabilities of chlorpyrifos adverse health effects occurring under the chronic exposure scenarios ranged from 1 to 8%, while those for acute exposure scenarios ranged from 31 to 34%. This study indicates that while the risks of chronic adverse health effects from chlorpyrifos exposure among the applicators were low, acute health risks were high., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The rearing temperature of the immature stages can have a significant impact on the life-history traits and the ability of adult mosquitoes to transmit diseases. This review assessed published evidence of the effects of temperature on the immature stages, life-history traits, insecticide susceptibility, and expression of enzymes in the adult Anopheles mosquito. Original articles published through 31 March 2021 were systematically retrieved from Scopus, Google Scholar, Science Direct, PubMed, ProQuest, and Web of Science databases. After applying eligibility criteria, 29 studies were included. The review revealed that immature stages of An. arabiensis were more tolerant (in terms of survival) to a higher temperature than An. funestus and An. quadriannulatus . Higher temperatures resulted in smaller larval sizes and decreased hatching and pupation time. The development rate and survival of An. stephensi was significantly reduced at a higher temperature than a lower temperature. Increasing temperatures decreased the longevity, body size, length of the gonotrophic cycle, and fecundity of Anopheles mosquitoes. Higher rearing temperatures increased pyrethroid resistance in adults of the An. arabiensis SENN DDT strain, and increased pyrethroid tolerance in the An. arabiensis SENN strain. Increasing temperature also significantly increased Nitric Oxide Synthase (NOS) expression and decreased insecticide toxicity. Both extreme low and high temperatures affect Anopheles mosquito development and survival. Climate change could have diverse effects on Anopheles mosquitoes. The sensitivities of Anopeheles mosquitoes to temperature differ from species to species, even among the same complex. Notwithstanding, there seem to be limited studies on the effects of temperature on adult life-history traits of Anopheles mosquitoes, and more studies are needed to clarify this relationship.

Background: Malaria is an infectious disease that causes many deaths in sub-Saharan Africa. In resource-poor malaria endemic communities, mosquito coils are commonly applied in households to repel the vector mosquito that transmits malaria parasites. In applying these coils, users have mainly been interested in the environmental health benefits potentially derived from repelling the mosquito, while oblivious of the environmental health risks that may be associated with exposure to emissions from the use of mosquito coil. This study evaluated the effectiveness of the mosquito coil, ascertained and/or estimated the toxic emissions that may emanate from the coil, and determined its overall appropriateness by conducting a risk-benefit analysis of the use of this strategy in malaria prevention at household levels., Methods: The repellent ability of mosquito coils was tested by conducting a mosquito knockdown/mortality test in experimental chambers synonymous of local room spaces and conditions. The gaseous and particulate emissions from the mosquito coil were also analysed. Additional scenarios were generated with the Monte Carlo technique and a risk-benefit analysis was conducted applying @Risk software., Results: Mosquito mortality arising from the application of various mosquito coils averagely ranged between 24 and 64%, which might not provide adequate repellency effect. Emissions from the mosquito coil were also found to contain CO, VOCs, SO 2 , NO 2 , PM 2.5 and PM 10 . The Hazard Index of the respective pollutants characterized over a lifetime exposure scenario was low (< 1 for each pollutant), which suggests that the concentrations of the specific chemicals and particulate matter emitted from the mosquito coil may not constitute adverse environmental health risk., Conclusion: Although the risk of morbidity from the use of the mosquito coil was low, the coil yielded limited protection as a mosquito avoidance method. It may, therefore, have a reduced benefit in controlling malaria and should be applied sparingly in a highly regulated manner only when traditionally proven effective vector control strategies are not available or too expensive for resource-poor malaria endemic regions.

Chlorpyrifos is a neurotoxic insecticide that is widely used in the agricultural sector of Ghana. The main objective of this study was to evaluate the levels of chlorpyrifos exposure and health risk among applicators (n = 21) on irrigated rice farms in Ghana, based on a typical application event. Pre- and post-application urine samples (24-h) were collected from the applicators and analysed for 3,5,6-trichloro-2-pyridinol (TCP), using LC-MS/MS. The levels of chlorpyrifos-absorbed dose with the applicators were estimated from the urinary TCP levels. Prior to application, the median absorbed dose of chlorpyrifos (background exposure) with the applicators was 0.2 μg/kg/day (range 0.05 to 2 μg/kg/day). Following application, the median absorbed dose of chlorpyrifos (application exposure) increased 30-fold to 6 μg/kg/day (range 0.7 to 74 μg/kg/day). The mean elimination half-life (t 1/2 ) of chlorpyrifos was calculated to be 50 h. Hazard quotient (HQ) values (HQ > 1) obtained with the chronic (10 μg/kg/day) and acute (100 μg/kg/day) guideline values of the WHO suggested no risk of chronic or acute health effects, respectively, among both the median and 5% highly exposed groups. However, HQ values (HQ > 1) obtained with the chronic (0.3 μg/kg/day) and acute (5 μg/kg/day) guideline values of the USEPA suggested risk of chronic and acute health effects, respectively, among both the median and 5% highly exposed groups. The quantity of chlorpyrifos formulation applied, spraying duration, and the number of spray tanks applied significantly correlated with the absorbed dose levels of chlorpyrifos from application exposure. Therefore, these factors suggest means to reduce exposure and consequent health risk among the applicators.

Generally, there is limited information on pesticide absorbed dose levels and health risk attributable to the dermal route of exposure among applicators. The objective of this study was to evaluate the absorbed dose levels and consequent health risk from dermal exposure to chlorpyrifos among applicators on rice farms in Ghana. The whole-body dosimetry technique was used to capture chlorpyrifos residues penetrating the applicators' clothing and reaching their skin, as well as residues reaching uncovered body areas of the applicators. Acute (ADD D ) and chronic (LADD D ) absorbed dose levels of chlorpyrifos were estimated from the residues and plotted as cumulative probability distributions. Health risk from chlorpyrifos exposure was characterized using the Hazard Quotient (HQ) technique. Three of the four acute exposure guideline values used in the study indicated that applicators, represented by the median-exposed (ADD D , 15 μg/kg/day) and the 5% - highly exposed (ADD D , 27 μg/kg/day) groups were at high risk of acute adverse health effects due to chlorpyrifos exposure, with HQ values ranging from 1.5 to 5 and 2.7 to 9, respectively. Regarding chronic adverse health effects, none of the guideline values suggested risk among the median-exposed group (LADD D , 0.3 μg/kg/day), with HQ values ranging from 0.03 to 1. However, two of the chronic exposure guideline values suggested that the 5%- highly exposed group (LADD D , 0.6 μg/kg/day) may be adversely affected, with HQ values ranging from 1.2 to 2. These findings highlight the importance of the dermal route as a major pesticide exposure pathway and suggest possible exposure minimization strategies., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Studies evaluating dermal exposure to pesticides among applicators in tropical countries have largely been conducted using the patch dosimetry and hand wiping/washing techniques. This study used the more accurate whole-body dosimetry technique to evaluate dermal exposure to chlorpyrifos among applicators on rice farms in Ghana. The exposure levels were plotted as Cumulative Probability Distribution (CPD). Total Dermal Exposure (TDE) of chlorpyrifos among the median exposed and the 5% highly exposed groups during a spray event were 24 mg and 48 mg, respectively. When these were converted as a percentage of the quantity of active ingredient applied (Unit Exposure, UE), UE values of 0.03% and 0.06% were found among the median exposed and the 5% highly exposed groups, respectively. Overall, the hands were the most contaminated anatomical regions of the applicators, both in terms of proportion of TDE (39%) and skin loading (13 μg/cm 2 ). Also, the lower anatomical region was more contaminated (82% of TDE) compared to the upper anatomical region (18% of TDE). The levels of chlorpyrifos TDE among the applicators were found to be influenced by the quantity of insecticide applied and the height of the crops sprayed (p < 0.05). The pesticide UE data of the present study can be used to estimate the levels of dermal exposure under similar pesticide use scenarios among applicators. The findings of the present study suggest that protecting the hands and the lower anatomical regions with appropriate PPE may significantly reduce exposure among applicators., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: The use of mosquito coils has gained widespread patronage in malaria-endemic countries, even though it is not a recommended preventive measure for avoiding mosquitoes. Mosquito coils contain insecticides, which are expected to vaporize slowly once the coil is lit, to provide protection against the mosquito. The mosquito coil base material contains a variety of compounds capable of burning slowly to gradually release the insecticide. The mosquito coil smoke, however, is potentially a source of indoor air pollution with implications for acute respiratory infections (ARI) and other illnesses. The present study investigated the application of mosquito coils and associated self-reported health issues in Ghana., Methods: A cross-sectional study was undertaken in which questionnaires were randomly administered to 480 households across four districts in Ghana. Respondents who exclusively applied mosquito coils were grouped as test cohort, while those who did not apply any mosquito repellency method constituted a control cohort., Results: The test group that applied mosquito coils reported malaria incidence rate of 86.3 %. The control group that did not apply any mosquito repellency method reported an incidence rate of malaria at 72.4 %. Chi square analysis suggested that the observed difference was statistically significant (x (2) = 4.25; p = 0.04). The number of respondents who reported symptoms of cough from mosquito coil application (52.6 % incidence rate) was marginally greater than their counterparts who did not apply coils (46.1 % incidence rate). It was also found that respondents with shortage of breath, which was used as a proxy for ARI, were more likely to have applied mosquito coil., Conclusions: The application of mosquito coils did not necessarily reduce the incidence of malaria in the study communities. It however presented a potential respiratory risk factor, which should be further investigated by critically examining exposure to particulate matter emissions from burning coils.