Mortality among pesticide applicators exposed to chlorpyrifos in the Agricultural Health Study

Exposure to pesticides and risk of colorectal cancer: A systematic review and meta-analysis

Colorectal cancer (CRC) is a widespread malignancy worldwide, and its relationship with pesticide exposure remains inconclusive. This study aims to elucidate the relationship between pesticide exposure and the risk of colon, rectal, or CRC, focusing on specific pesticide groups. We conducted an extensive literature search for peer-reviewed studies published up to March 31, 2023. Summary risk ratios (RR) and their corresponding 95% confidence intervals (CI) were calculated using stratified random-effects meta-analyses, taking into account different types of exposure and outcomes, and various exposed populations and pesticide subgroups. This approach aimed to address the substantial heterogeneity observed across the literature. We also assessed heterogeneity and potential small-study effects to ensure the robustness of our findings. From the 50 studies included in this review, 33 contributed to the meta-analysis. Our results indicate a significant association between herbicide exposure and colon cancer in both lifetime-days (LDs) (RR = 1.20; 95% CI = 1.01-1.42) and intensity-weighted lifetime-days (IWLDs) (RR = 1.29, 95% CI = 1.12-1.49) exposure. Similarly, insecticide exposure was associated with an increased risk of colon cancer in IWLDs (RR = 1.32; 95% CI = 1.02-1.70) exposure, and rectal cancer in any versus never exposure (RR = 1.21; 95% CI = 1.07-1.36), IDs (RR = 1.86; 95% CI = 1.30-2.67) and IWLDs (RR = 1.70; 95% CI = 1.03-2.83) exposure. While these findings suggest significant associations of herbicide and insecticide exposure with colon and rectal cancer, respectively, further research is needed to explore the impact of other pesticide groups and deepen our understanding of pesticide exposure. These results have important implications for policymakers and regulators, underscoring the need for stricter supervision and regulation of pesticide use to mitigate CRC risk.

Association of pesticide exposure with neurobehavioral outcomes among avocado farmworkers in Mexico

BACKGROUND AND AIM

To date, few studies have focused on the health effects of pesticide exposure among avocado farmworkers. We examined the association of exposure to insecticides, fungicides, and herbicides with cognitive and mental health outcomes among these avocado workers from Michoacan, Mexico.

MATERIALS AND METHODS

We conducted a cross-sectional study of 105 avocado farmworkers between May and August 2021. We collected data on self-reported pesticide use during the 12 months prior to the baseline survey and estimated annual exposure-intensity scores (EIS) using a semi-quantitative exposure algorithm. We calculated specific gravity adjusted average concentrations of 12 insecticide, fungicide, or herbicide metabolites measured in urine samples collected during two study visits (8-10 weeks apart). We assessed participants' cognitive function and psychological distress using the NIH Toolbox Cognition Battery and the Brief Symptom Inventory 18 (BSI-18), respectively. We examined individual associations of EIS and urinary pesticide metabolites with neurobehavioral outcomes using generalized linear regression models. We also implemented Bayesian Weighted Quantile Sum (BWQS) regression to evaluate the association between a pesticide metabolite mixture and neurobehavioral outcomes.

RESULTS

In individual models, after adjusting for multiple comparisons, higher concentrations of hydroxy-tebuconazole (OH-TEB, metabolite of fungicide tebuconazole) were associated with higher anxiety (IRR per two-fold increase in concentrations = 1.26, 95% CI:1.08, 1.48) and Global Severity Index (GSI) (IRR = 1.89, 95% CI:1.36, 2.75) scores, whereas higher concentrations of 3,5,6-trichloro-2-pyridinol (TCPy, metabolite of chlorpyrifos) were associated with lower GSI scores (IRR = 0.69, 95% CI: 0.56, 0.85). In BWQS analyses, we found evidence of a mixture association of urinary pesticide metabolites with higher anxiety (IRR = 1.72, 95% CrI: 1.12, 2.55), depression (IRR = 4.60, 95% CrI: 2.19, 9.43), and GSI (IRR = 1.99, 95% CrI: 1.39, 2.79) scores. OH-TEB and hydroxy-thiabendazole (metabolite of fungicide thiabendazole) combined contributed 54%, 40%, and 54% to the mixture effect in the anxiety symptoms, depression symptoms, and overall psychological distress models, respectively.

CONCLUSIONS

We found that exposure to tebuconazole and thiabendazole, fungicides whose effects have been rarely studied in humans, may be associated with increased psychological distress among avocado farmworkers. We also observed that exposure to chlorpyrifos may be associated with decreased psychological distress.

Pesticides and Bladder Cancer: Mechanisms Leading to Anti-Cancer Drug Chemoresistance and New Chemosensitization Strategies

Multiple risk factors have been associated with bladder cancer. This review focuses on pesticide exposure, as it is not currently known whether agricultural products have a direct or indirect effect on bladder cancer, despite recent reports demonstrating a strong correlation. While it is known that pesticide exposure is associated with an increased risk of bladder cancer in humans and dogs, the mechanism(s) by which specific pesticides cause bladder cancer initiation or progression is unknown. In this narrative review, we discuss what is currently known about pesticide exposure and the link to bladder cancer. This review highlights multiple pathways modulated by pesticide exposure with direct links to bladder cancer oncogenesis/metastasis (MMP-2, TGF-β, STAT3) and chemoresistance (drug efflux, DNA repair, and apoptosis resistance) and potential therapeutic tactics to counter these pesticide-induced affects.

Suicide and suicidality in people exposed to pesticides: A systematic review and meta-analysis

Exposure to pesticides has been proposed to be a positive association in suicide and suicidality. Many studies have explored this topic, but have reported inconsistent findings. We carried out a systematic review and meta-analysis of the now existing evidence on the association between pesticide exposure and the risk of suicide and suicidality. We searched PubMed, EMBASE and Web of Science databases for studies published up to February 1, 2023. For studies that provided detailed data, we applied quantitative meta-analysis to calculate Odds ratio (OR) with 95% Confidence Intervals (CIs) to evaluate the results. Heterogeneity among the included studies was assessed using Cochran's Q test, I² statistic and tau-squared (τ²). Publication bias was evaluated by funnel plots, Egger's test, and Begg's test. In addition, subgroup analyses according to pesticides category and geographical area were performed. 2906 studies were initially identified, and 20 studies were eventually included. Fifteen of the studies were on suicide deaths and suicide attempts, and five were on suicidal ideation. Pesticide exposure was positively related to suicide deaths and suicide attempts (pooled OR = 1.31; 95%CI: 1.04-1.64, p < 0.001) and suicidal ideation (pooled OR = 2.43; 95%CI: 1.51-3.91, p = 0.015). In the subgroup analysis, mixed pesticide type (pooled OR = 1.55; 95%CI: 1.39-1.74) increased the risk of suicide deaths and suicide attempts. The results of the analysis by geographic area showed that the risk of suicide deaths and suicide attempts with pesticide exposure was 2.27 (95%CI = 1.36-3.78), and 1.33 (95%CI = 1.14-1.56) in Asia and Europe, respectively. The risk of suicidal ideation caused by pesticide exposure in Asia and America were 2.19 (95%CI = 1.08-4.42) and 2.99 (95%CI = 1.76-5.06). In conclusion, pesticide exposure may increase the risk of suicide and suicidality based on the current evidence.

Could pesticide exposure be implicated in the high incidence rates of depression, anxiety and suicide in farmers? A systematic review

Pesticide exposure and poisoning may rise the risk of mental health problems and suicidal tendencies. To explore the potential connection between chronic occupational exposure to pesticides and depression, anxiety, and suicide-related outcomes in farmers, a systematic review was performed. Systematic review protocol is available in PROSPERO registration number CRD42022316285. A total of fifty-seven studies met inclusion criteria: twenty-nine on depression or other mental disorders, twelve on suicide (two of them on both depression and suicide), and fourteen on pesticide poisoning or self-poisoning and death. Among the fifty-seven selected studies, eighteen were conducted in Asia, seventeen in North America, fourteen in South America, seven in European Union, one in Africa, and one in Australia/Oceania. Selected studies demonstrated an increased prevalence of depressive disorders in farmworkers exposed to pesticides as well as an increased self-reported prevalence of depression in this population. Moreover, previous pesticide poisoning increased the risk estimates for depression or other mental disorders as compared with chronic pesticide exposure. Severe pesticide poisoning and multiple poisoning showed increased risks of depressive symptoms compared with milder cases. In addition, financial difficulties and poor health were positively correlated with depression. Among studies on suicide, nine of them found that suicide rates increased in areas devoted to agriculture with intensive pesticide consumption. Moreover, studies demonstrate a higher suicide risk among farmers. The present review suggests more attention to the farmer's mental health and more detailed studies on occupational exposure to the mixture of these compounds.

Air pollution, investor sentiment and stock liquidity

With the aggravation of air pollution, the impact of air pollution on the stock market, especially from the perspective of investor sentiment, has been of great concern and widely discussed. Based on data from China's A-share listed firms from January 1, 2016, to December 31, 2020, the relationship between urban air pollution and stock liquidity of listed firms and the internal mechanism is examined. Firstly, based on local preference theory, we start by predicting the impact of air pollution on stock liquidity. We, then, build a regression model for air pollution and stock liquidity, introducing the intermediary effect model to detect the relationship between the two and its mechanism. Finally, by subdividing the samples, we discuss the differential impact of air pollution on stock liquidity under different circumstances. We found that when air pollution worsens it reduces stock liquidity. The results of the mechanism analysis show that investor sentiment plays an intermediary role in the process of air pollution affecting stock liquidity, and pessimism induced by air pollution can reduce stock liquidity. Heterogeneity test results show that there are differences in the impact of air pollution on stock liquidity between heavily polluting firms and non-heavily polluting firms, different industries, different city sizes, and different levels of air pollution, has a greater effect in non-heavily polluting enterprises, manufacturing and other industries, medium sized cities and light pollution. The results of this research have important reference value for environmental protection departments to establish and improve air pollution monitoring systems and for listed firms to improve stock liquidity and deal with the environmental financial risks appropriately.

Potential Effects on Mental Health Status Associated with Occupational Exposure to Pesticides among Thai Farmers

Pesticide-related mental health issues in Thailand, an upper-middle-income country, are not well known. This study aimed to investigate the association between the history of occupational exposure to pesticides and the mental health of Thai farmers. A cross-sectional study was carried out in the areas around Chiang Mai, a large city in Northern Thailand, between June 2020 and January 2021. A total of 6974 farmers from six districts were interviewed to determine whether they regularly experienced symptoms related to mental health by the Self-Reporting Questionnaire (SRQ-20) as well as their lifetime history of agricultural pesticide exposure from 31 active ingredients and five functional categories: insecticides, herbicides, fungicides, rodenticides, and molluscicides. The cut-off of 6 was used to evaluate probable mental disorder. Most of the farmers under investigation were men (53.8%), with a mean age of 55.2 (11.7) years, and were involved mainly in the planting of rice, fruit, and vegetables. About 86.7% reported having used pesticides on their crops at some point in their lives-mostly glyphosate, paraquat, 2,4-D, methomyl, and carbofuran. All functional groups, as well as pesticide classes like organochlorines, organophosphates, and carbamates, were significantly associated with a higher risk of probable mental disorder based on exposure duration, frequency, personal protective equipment usage, and hygienic behavior. In a model with multiple pesticides, there was an association between mental disorder and exposure to endosulfan (AOR = 2.27, 95%CI = 1.26-4.08) and methyl parathion (AOR = 2.26, 95%CI = 1.26-4.06). Having previously reported pesticide poisoning symptoms was related to mental disorder (AOR = 7.97, 95%CI = 5.16-12.31), the findings provided evidence of pesticide exposure posing a risk to farmers' mental health, particularly long-term and high-intensity exposure.

Rapid and non-invasive surface-enhanced Raman spectroscopy (SERS) detection of chlorpyrifos in fruits using disposable paper-based substrates charged with gold nanoparticle/halloysite nanotube composites

Chlorpyrifos is one of the most widely used organophosphate insecticides in agricultural production. Nevertheless, the residues of chlorpyrifos in agricultural by-product seriously threaten human health. Thus, the ultrasensitive detection of chlorpyrifos residues in agri-food products is of great demand. Herein, an AuNP/HNT-assembled disposable paper SERS substrate was prepared by an electrostatic self-assembly method to detect chlorpyrifos residues. The AuNP/HNT paper substrate exhibited high SERS activity, good reproducibility, and long-term stability, which was successfully used for quantitative detection of chlorpyrifos; the detection limit reached 7.9 × 10^-9 M. For spiked apple samples the calculated recovery was 87.9% with a RSD value of 6.1%. The excellent detection ability of AuNP/HNT paper-based SERS substrate indicated that it will play an important role in pesticide detection in the future. AuNP/HNT assembled disposable paper SERS substrate was prepared by an electrostatic self-assembly method to detect chlorpyrifos residues in fruits.

Toxic Effects of Glyphosate on the Nervous System: A Systematic Review

Glyphosate, a non-selective systemic biocide with broad-spectrum activity, is the most widely used herbicide in the world. It can persist in the environment for days or months, and its intensive and large-scale use can constitute a major environmental and health problem. In this systematic review, we investigate the current state of our knowledge related to the effects of this pesticide on the nervous system of various animal species and humans. The information provided indicates that exposure to glyphosate or its commercial formulations induces several neurotoxic effects. It has been shown that exposure to this pesticide during the early stages of life can seriously affect normal cell development by deregulating some of the signaling pathways involved in this process, leading to alterations in differentiation, neuronal growth, and myelination. Glyphosate also seems to exert a significant toxic effect on neurotransmission and to induce oxidative stress, neuroinflammation and mitochondrial dysfunction, processes that lead to neuronal death due to autophagy, necrosis, or apoptosis, as well as the appearance of behavioral and motor disorders. The doses of glyphosate that produce these neurotoxic effects vary widely but are lower than the limits set by regulatory agencies. Although there are important discrepancies between the analyzed findings, it is unequivocal that exposure to glyphosate produces important alterations in the structure and function of the nervous system of humans, rodents, fish, and invertebrates.

Clinical Epidemiology and Predictors of Outcome in Chlorpyrifos Poisoning in Farming and Allied Agricultural Workers in East Godavari, Andhra Pradesh

BACKGROUND

Chlorpyrifos is the ninth most consumed pesticide for agricultural purposes in India. It is a chlorinated organophosphate that also causes poisoning in non-target species such as humans. There is a scarcity of published literature on chlorpyrifos intoxication in the Indian scenario.

OBJECTIVE

The objective of the study was to find out the clinical epidemiology and factors influencing the outcome of chlorpyrifos poisoning in the farming and allied agricultural workers.

METHODOLOGY

The patient record-based cross-sectional study was carried out on 40 confirmed cases of chlorpyrifos poisoning in a tertiary care teaching hospital in East Godavari district, a predominantly agrarian region in the state of Andhra Pradesh. Clinic-demographic profile, aspects of poisoning, outcome in terms of recovery, death, ventilator support were obtained. Mortality or requirement of ventilator support was classified as a bad outcome. Carlsons' Co-morbidity Index, Poison Severity Score, and Glasgow Coma Scale score at the time of admission were assessed objectively. The strength of association between the predictor variables and the outcome was represented using the odds ratio. Statistical analysis was performed using Graph Pad Prism 8.0 trial version.

RESULTS

Chlorpyrifos poisoning constituted about 10% of pesticide poisoning and 25% of such cases had a poor outcome. The mean age was 44.73 ± 10.76 years, the majority being farmers. Younger age (<40 years), early reporting to hospital, Carlsons' Co-morbidity Index of less than 8, Glasgow Coma Scale score of more than 12, and Poison severity score of less than 2 were significantly associated with favorable outcome (P < 0.005). During admission, 60% of cases had a plasma pseudocholinesterase level of less than 1000 U/L. Lower plasma pseudocholinesterase was associated with a poor outcome (OR 9.62 CI 4.05-22.84).

CONCLUSIONS

Farmers and allied agricultural workers are susceptible to chlorpyrifos intoxication. Along with clinical and laboratory parameters, Carlsons' Co-morbidity Index, Glasgow Coma Scale score, and Poison severity score at the time of admission are seen as reliable predictors of outcome.

Association between pesticide exposure and colorectal cancer risk and incidence: A systematic review

BACKGROUND

Studies investigating the association between pesticide exposure and colorectal cancer (CRC) risk have been inconclusive.

OBJECTIVES

Investigate the association between pesticide exposure and CRC risk through a systematic literature review.

METHODS

CRC has the fourth-highest rate of cancer-caused death in the US after lung cancer, breast cancer in women, and prostate cancer in men. Here we have conducted a systematic literature search on studies examining the association between any pesticide exposure and CRC risk using PubMed, MEDLINE via EBSCO host, and Embase according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.

RESULTS

Following the review, 139 articles were included for qualitative evaluation. Study participants were farmers, pesticide applicators, pesticide manufacturers, spouses of pesticide applicators, farm residents, Korean veterans of the Vietnam War, rural communities, and those who consumed food with pesticide residues. The studies' results were split between those with significant positive (39 significant results) and inverse (41 significant results) associations when comparing pesticide exposure and CRC risk.

DISCUSSION

From our literature review, we have identified a similar number of significant positive and inverse associations of pesticide exposure with CRC risk and therefore cannot conclude whether pesticide exposure has a positive or inverse association with CRC risk overall. However, certain pesticides such as terbufos, dicamba, trifluralin, S-ethyl dipropylthiocarbamate (EPTC), imazethapyr, chlorpyrifos, carbaryl, pendimethalin, and acetochlor are of great concern not only for their associated elevated risk of CRC, but also for the current legal usage in the United States (US). Aldicarb and dieldrin are of moderate concern for the positive associations with CRC risk, and also for the illegal usage or the detection on imported food products even though they have been banned in the US. Pesticides can linger in the soil, water, and air for weeks to years and, therefore, can lead to exposure to farmers, manufacturing workers, and those living in rural communities near these farms and factories. Approximately 60 million people in the US live in rural areas and all of the CRC mortality hotspots are within the rural communities. The CRC mortality rate is still increasing in the rural regions despite the overall decreasing of incidence and mortality of CRC elsewhere. Therefore, the results from this study on the relationship between pesticide exposure and CRC risk will help us to understand CRC health disparities.

The Toxic Effects of Glyphosate, Chlorpyrifos, Abamectin, and 2,4-D on Animal Models: A Systematic Review of Brazilian Studies

Brazil is a global agricultural commodity producer and the largest consumer of pesticides. Pesticide use in Brazil comprised 549 280 tons in 2018. In the country, soybean, corn, and sugar cane are extensively produced, which are the most pesticides demanding crops. In the last years, the records of new pesticides were the highest in the historical series. They can persist in soil or water, accumulate in organisms, and contaminate workers and the general population through the air, water, or food. This review aimed to gather toxicological data obtained by animal models exposed to 4 pesticides: glyphosate, chlorpyrifos, abamectin, and 2,4-D. An additional goal was to compose an overview of how this subject has been approached, surveying which research groups are working on this field, where they are located, and relations with pesticides used in those regions. We collected the papers from the platforms PubMed, Scopus, Scielo, and Web of Science, performed in Brazil from 2014 to 2019. After two-step blind selection using the software Rayyan QCRI by different authors, 67 studies were selected to extract data. We observed that research is more concentrated in the South region, followed by the Southeast and Midwest, with 43%, 32%, and 23% of the studies, respectively. The prevalent institutions are from the states of Rio Grande do Sul, São Paulo, and Goiás. The effects on a variety of biomarkers help predict the potential risks to humans and nontarget organisms. The prevalent animal model was fish (36%). Overall, the main toxic effects evaluated were mortality, abnormalities in the blood cells, developmental abnormalities, and behavior alterations. Integr Environ Assess Manag 2021;17:507-520. © 2020 SETAC.

A Rare Case of Suicide by Ingestion of Phorate: A Case Report and a Review of the Literature

Phorate is a systemic organophosphorus pesticide (OP) that acts by inhibiting cholinesterases. Recent studies have reported that long-term low/moderate exposure to OP could be correlated with impaired cardiovascular and pulmonary function and other neurological effects. A 70-year-old farmer died after an intention ingestion of a granular powder mixed with water. He was employed on a farm for over 50 years producing fruit and vegetables, and for about 20 years, he had also applied pesticides. In the last 15 years, he used phorate predominantly. The Phorate concentration detected in gastric contents was 3.29 µg/mL. Chronic exposure to phorate is experimentally studied by histopathological changes observed in the kidney. In the light of current literature, our case confirms that there is an association between renal damage and chronic exposure to phorate in a subject exposed for years to the pesticide. Autopsies and toxicological analyses play a key role in the reconstruction of the dynamics, including the cause of the death.

Occupational health and safety in agriculture. A systematic review

Introduction: The prevalence of occupational diseases in the agricultural sector is higher than in other industries, since agricultural workers are at higher risk of exposure to different chemicals and pesticides, and are more prone to occupational accidents.Objective: To conduct a review of recent literature on occupational health and risk in agriculture.Materials and methods: A literature search was conducted in PubMed, SciencieDirect and Scopus using the following search strategy: type of articles: original research papers; language: English; publication period: 2006-2016; search terms: "agricultural health", "agrarian health", "risk factors", "epidemiology", "causality" and "occupational", used in different combinations ("AND" and "OR").Results: The search yielded 350 articles, of which 102 met the inclusion criteria. Moreover, 5 articles were found in grey literature sources and included in the final analysis. Most research on this topic has been conducted in the United States, which produced 91% (97/107) of the articles included.Conclusions: Most studies on health and safety in agriculture focused primarily on the harmful effects of occupational exposure to agrochemicals and pesticides, and the consequences of occupational accidents. However, since more than 90% of these studies come from the United States, a more comprehensive approach to health in agriculture is required, since what is reported here may be far from the reality of other regions, especially Latin America.

Chlorpyrifos-induced cell proliferation in human breast cancer cell lines differentially mediated by estrogen and aryl hydrocarbon receptors and KIAA1363 enzyme after 24 h and 14 days exposure

Organophosphate biocide chlorpyrifos (CPF) is involved with breast cancer. However, the mechanisms remain unknown. CPF increases cell division in MCF-7 cells, by estrogen receptor alpha (ERα) activation, although it is a weak ERα agonist, suggesting other mechanisms should be involved. Aromatic hydrocarbon receptor (AhR) activation increases cell division in human breast cancer cells, and CPF strongly activates it. Finally, the KIAA1363 enzyme, which is regulated by CPF, is overexpressed in cancer cells. Accordingly, we hypothesized that CPF or its metabolite chlorpyrifos-oxon (CPFO) could induce cell viability promotion in MCF-7 and MDA-MB-231 cell lines, through mechanisms related to ERα, AhR, and KIAA1363, after 24 h and 14 days treatment. Results show that, after acute and long-term treatment, CPF and CPFO alter differently KIAA1363, AhR, ER and cytochrome P450 isoenzyme 1A1 (CYP1A1) expression. In addition, they induced cell proliferation through ERα activation after 24 h exposure in MCF-7 cells and through KIAA1363 overexpression and AhR activation in MCF-7 and MDA-MB-231 cells after acute and long-term treatment. The results obtained in this work provide new information relative to the mechanisms involved in the CPF toxic effects that could lead to breast cancer disease.

Outcome of patients with chlorpyrifos intoxication

INTRODUCTION

There is a paucity of literature analyzing outcome of chlorpyrifos intoxication.

METHODS

A total of 40 patients with chlorpyrifos intoxication were seen at Chang Gung Memorial Hospital between 2008 and 2017. Patients were stratified into two subgroups according to their prognosis, as good (n = 12) or poor (n = 28). Good prognosis group were defined as patients who survived without serious complications, and poor prognosis group included patients who died and survived after development of severe complications. Demographic, clinical, laboratory, and mortality data were obtained for analysis.

RESULTS

Patients aged 53.8 ± 16.3 years and most were male (80.0%). All patients (100.0%) developed acute cholinergic crisis such as emesis (45.0%), respiratory failure (42.5%), tachycardia (30.0%), kidney injury (22.5%), and seizure (7.5%). Intermediate syndrome developed in 12.5% of patients, but none had delayed neuropathy (0%). The poor prognosis group suffered higher incidences of respiratory failure (p = 0.011), kidney injury (p = 0.026), and prolonged corrected QT interval (p = 0.000), and they had higher blood urea nitrogen level (p = 0.041), lower Glasgow coma scale score (p = 0.011), and lower monocyte count (p = 0.023) than good prognosis group. All patients were treated with atropine and pralidoxime therapy, but six patients (15.0%) still died of intoxication. In a multivariate logistic regression model, blood urea nitrogen was a significant risk factor for poor prognosis (odds ratio: 1.375, 95% confidence interval: 1.001-1.889, p = 0.049). Nevertheless, no mortality risk factor could be identified.

CONCLUSION

The mortality rate of patients with chlorpyrifos intoxication was 15.0%. Furthermore, acute cholinergic crisis, intermediate syndrome, and delayed neuropathy developed in 100.0%, 12.5%, and 0% of patients, respectively.

Risk for Depressive Symptoms and Suicide Among U.S. Primary Farmers and Family Members: A Systematic Literature Review

Background: About 84% of the agriculture, fishing, and forestry occupational sector is comprised of farmers. This sector is at high risk for suicide in the United States. Recent disasters and trade upheavals may make farmers and their families more vulnerable to depression and suicide. This review focused on the risk for depression and suicide among United States’ primary farm operators and their families. Methods: A systematic search of the literature published between January 2000 and June 2019, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was conducted. Results: A total of 30 articles met full inclusion criteria. Seventeen reports emanated from the midwest. Twenty studies used a cross-sectional design, primarily assessing a convenience sample or random stratified sample from a limited geographic area. We discovered only one intervention evaluation study. Depressive symptoms were assessed as part of the studies, but it was not the major focus. A variety of instruments measured depressive symptoms, with the Centers for Disease Control Epidemiologic Studies—Depression (CES-D) Scale used more frequently than other scales. Thirteen studies focused on the relationship between pesticide/chemical exposure and depression or suicide risk. Increased stress, poor physical health, compromised financial position, and previous injury were among the leading indicators of depression. Conclusion/Application to Practice: The limited number of studies that was discovered identified the need for more robust science where the risk for depression and suicide is the primary focus of the study and for intervention studies grounded in science. Occupational health providers should be vigilant about farm exposure and be aware of factors that may influence depressive symptoms of workers who operate farm establishments.

Detection of systemic pesticide residues in tea products at trace level based on SERS and verified by GC-MS

Surface-enhanced Raman spectroscopy (SERS) has the potential to detect pesticide residues in agricultural products. However, some systemic pesticides, such as chlorpyrifos, can enter the plant tissue, and not just stay on the surface. Consequently, many SERS studies halted at practical application because of its complexity. In this work, SERS technology was used to detect chlorpyrifos residues in tea products at the semiquantitative level. A simple pretreatment method effectively avoided interference of other fluorescent substances, and all major peaks could be distinguished on the basis of a novel substrate. A principal component analysis algorithm was applied to form a regression model, and a nanogram detection limit was obtained. Furthermore, chlorpyrifos residues in the same tea products were also measured by gas chromatography-mass spectrometry, and the results show a small range of errors. From the comparative study of the two detection methods, the results suggest the great promise of SERS technology for rapid inspection of agricultural products.

Reliability and factorial validity of a questionnaire to assess organophosphate pesticide exposure to agricultural workers in Maule, Chile

The aim was to evaluate the reliability and validity of a questionnaire to assess organophosphate pesticide (OP) exposure in agricultural workers. We then enrolled a random sample of 114 agricultural workers from the region of Maule, Chile (mean age = 50 years [SD = 12]). An internal consistency analysis (Cronbach's alpha> 0.70) and a Varimax rotational factorial analysis were applied. The instrument had a high reliability to predict likely occupational pesticide exposures: Cronbach's alpha = 0.95, the Kaiser-Meyer-Olkin (KMO) measure was 0.90 and the Bartell sphericity test = p < 0.001. Four factors explaining 68% of the variance were extracted. The factors identified were as follows: (1) labor conditions during application of OPs; (2) use of personal protective equipment; (3) workplace conditions related to OP exposure and (4) home conditions related to OP exposure. The questionnaire has adequate metric properties to characterize likely OP exposure of agricultural workers and to explore associated working and home conditions.

Ambient air pollution exposure and emergency department visits for substance abuse

There is growing evidence supporting the notion that exposure to air pollution can contribute to cognitive and psychiatric disorders, including depression and suicide. Given the relationship between exposure to acute stressors and substance abuse, the present study assessed the association between exposure to ambient air pollution and emergency department (ED) visits for alcohol and drug abuse. ED visit data selected according to International Classification of Disease (ICD-9) coding 303 (alcohol dependence syndromes) and 305 (non-dependent abuse of drugs) were collected in five hospitals in Edmonton, Canada. A time-stratified case crossover design was used. Conditional logistic regression was applied to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Season, temperature, and relative humidity were adjusted for using natural splines.

Results are reported for an increase in pollutant concentrations equivalent to one interquartile range (IQR). Statistically significant positive associations with substance abuse were observed for CO, NO₂ and particulate matter with an aerodynamic diameter less than 10 μm (PM₁₀) and 2.5 μm (PM_2.5). The strongest results were obtained in the cold period (October–March) for 1-day lagged CO (OR = 1.03, 95% CI: 1.01, 1.05, IQR = 0.4 ppm) and NO₂ (OR = 1.04, 95% CI: 1.01, 1.07, IQR = 12.8 ppb); ORs were also significant for CO and NO₂ with lags of 2 to 6 days and 2 to 7 days, respectively. The study suggests that, even at low levels, increases in ambient CO, NO₂, and PMs are associated with increased hospital admissions for substance abuse, possibly as a result of impacts of air quality on mental health or depression.

Behavioral and Immunohistochemical Study of the Effects of Subchronic and Chronic Exposure to Glyphosate in Mice

Many epidemiological studies have described an adolescent-related psychiatric illness and sensorimotor deficits after Glyphosate based herbicide (GBH) exposure. GBH exposure in animal models of various ages suggests that it may be neurotoxic and could impact brain development and subsequently, behavior in adulthood. However, its neurotoxic effects on adolescent brain remain unclear and the results are limited. The present study was conducted to evaluate the neurobehavioral effects of GBH following acute, subchronic (6 weeks) and chronic (12 weeks) exposure (250 or 500 mg/kg/day) in mice treated from juvenile age until adulthood. Mice were subjected to behavioral testing with the open field (OF), the elevated plus maze, the tail suspension and Splash tests (STs). Their behaviors related to exploratory activity, anxiety and depression-like were recorded. After completion of the behavioral testing, adult mice were sacrificed and the expression of tyrosine hydroxylase (TH) in the substantia nigra pars compacta (SNc) and serotonin (5-HT) in the dorsal raphe nucleus (DRN), the basolateral amygdala (BLA) and the ventral medial prefrontal cortex (mPFC) was evaluated using immunohistochemical procedure. Our results indicate that unlike acute exposure, both subchronic and chronic exposure to GBH induced a decrease in body weight gain and locomotor activity, and an increase of anxiety and depression-like behavior levels. In addition, the immunohistochemical findings showed that only the chronic treatment induced a reduction of TH-immunoreactivity. However, both subchronic and chronic exposure produced a reduction of 5-HT-immunoreactivity in the DRN, BLA and ventral mPFC. Taken together, our data suggest that exposure to GBH from juvenile age through adulthood in mice leads to neurobehavioral changes that stem from the impairment of neuronal developmental processes.

Neurotoxicity in Preclinical Models of Occupational Exposure to Organophosphorus Compounds

Organophosphorus (OPs) compounds are widely used as insecticides, plasticizers, and fuel additives. These compounds potently inhibit acetylcholinesterase (AChE), the enzyme that inactivates acetylcholine at neuronal synapses, and acute exposure to high OP levels can cause cholinergic crisis in humans and animals. Evidence further suggests that repeated exposure to lower OP levels insufficient to cause cholinergic crisis, frequently encountered in the occupational setting, also pose serious risks to people. For example, multiple epidemiological studies have identified associations between occupational OP exposure and neurodegenerative disease, psychiatric illness, and sensorimotor deficits. Rigorous scientific investigation of the basic science mechanisms underlying these epidemiological findings requires valid preclinical models in which tightly-regulated exposure paradigms can be correlated with neurotoxicity. Here, we review the experimental models of occupational OP exposure currently used in the field. We found that animal studies simulating occupational OP exposures do indeed show evidence of neurotoxicity, and that utilization of these models is helping illuminate the mechanisms underlying OP-induced neurological sequelae. Still, further work is necessary to evaluate exposure levels, protection methods, and treatment strategies, which taken together could serve to modify guidelines for improving workplace conditions globally.

Anxiety and depression following cumulative low-level exposure to organophosphate pesticides

Previous research suggests that individuals with a prior history of pesticide poisoning are at increased risk of psychiatric disorder (Freire and Koifman, 2013), but findings regarding the impact of cumulative low-level exposure are inconsistent. The aim of the current study was to investigate whether sheep farmers with a history of low-level exposure to organophosphate pesticides (1) report a higher level of psychological distress on subjective symptom questionnaires, compared to unexposed controls (2) also meet internationally agreed diagnostic criteria for a psychiatric disorder more often than unexposed controls. 127sheep farmers were evaluated and compared to 78 unexposed controls, matched in terms of gender, education, level of intelligence, working status and area of residence. Both self-report measures and structured clinical interviews were used to assess mental health. The exposed cohort reported significantly higher rates of anxiety and depression when self-report questionnaires were used to evaluate mood, even when stressful life events, demographic and physical health factors were taken into account. However, when diagnostic interviews were used to assess mood, this pattern only held true for anxiety.

Exposure to pesticides and prostate cancer: systematic review of the literature

INTRODUCTION

Investigations about the association between prostate cancer and environmental and/or occupational pesticide exposure have evidenced a possible role of these chemical substances on tumor etiology, related to their action as endocrine disruptors.

OBJECTIVE

To assess the association between pesticide exposure and prostate cancer by conducting a systematic review of the scientific literature.

MATERIALS AND METHODS

Articles published until August 18, 2015 were searched in the databases MEDLINE/Pubmed, Scielo, and Lilacs using the keywords "pesticides" and "prostate cancer". Only the analytical observational studies whose methodological quality met the criteria established by the New Castle-Ottawa scale were included in this review.

RESULTS

The review included 49 studies published between 1993 and 2015. All studies were in English and analyzed exposure to pesticides and/or agricultural activities. Most studies (32 articles) found a positive association between prostate cancer and pesticides or agricultural occupations, with estimates ranging from 1.01 to 14.10.

CONCLUSION

The evidence provided by the reviewed studies indicates a possible association between the development of prostate cancer and pesticide exposure and/or agricultural occupations.

Chlorpyrifos promotes colorectal adenocarcinoma H508 cell growth through the activation of EGFR/ERK1/2 signaling pathway but not cholinergic pathway

Aside from the effects on neuronal cholinergic system, epidemiological studies suggest an association between chlorpyrifos (CPF) exposure and cancer risk. This in vitro study examined the effects of CPF and its toxic metabolite, chlorpyrifos oxon (CPF-O), on the growth of human colorectal adenocarcinoma H508, colorectal adenocarcinoma HT-29, normal colon epithelial CCD841, liver hepatocellular carcinoma HepG2, and normal liver hepatocyte THLE-3 cells. The results showed that CPF (5-100 μM) concentration-dependently increased viability of H508 and CCD841 cells in serum-free conditions. This increasing trend was not found in HT-29, HepG2 and THLE-3 cells. In contrast, CPF-O (50-100 μM) reduced the viability of all cell lines. Cell cycle analysis showed the induction of cells in the S phase, and EdU incorporation assay revealed the induction of DNA synthesis in CPF-treated H508 cells indicating that CPF promotes cell cycle progression. Despite the observation of acetylcholinesterase activity inhibition and reactive oxygen species (ROS) generation, atropine (a non-selective muscarinic acetylcholine receptor antagonist) and N-acetylcysteine (a potent antioxidant) failed to inhibit the growth-promoting effect of CPF. CPF increased the phosphorylation of epidermal growth factor receptor (EGFR) and its downstream effector, extracellular signal regulated kinase (ERK1/2), in H508 cells. AG-1478 (a specific EGFR tyrosine kinase inhibitor) and U0126 (a specific MEK inhibitor) completely mitigated the growth promoting effect of CPF. Altogether, these results suggest that EGFR/ERK1/2 signaling pathway but not cholinergic pathway involves in CPF-induced colorectal adenocarcinoma H508 cell growth.

Prenatal nicotine changes the response to postnatal chlorpyrifos: Interactions targeting serotonergic synaptic function and cognition

Nicotine and chlorpyrifos are developmental neurotoxicants that target serotonin systems. We examined whether prenatal nicotine exposure alters the subsequent response to chlorpyrifos given postnatally. Pregnant rats received nicotine throughout gestation at 3mg/kg/day, a regimen designed to achieve plasma levels seen in smokers; chlorpyrifos was given to pups on postnatal days (PN) 1-4 at 1mg/kg, just above the detection threshold for brain cholinesterase inhibition. We assessed long-term effects from adolescence (PN30) through full adulthood (PN150), measuring the expression of serotonin receptors and serotonin turnover (index of presynaptic impulse activity) in cerebrocortical brain regions encompassing the projections that are known targets for nicotine and chlorpyrifos. Nicotine or chlorpyrifos individually increased the expression of serotonin receptors, with greater effects on males than on females and with distinct temporal and regional patterns indicative of adaptive synaptic changes rather than simply an extension of initial injury. This interpretation was confirmed by our finding an increase in serotonin turnover, connoting presynaptic serotonergic hyperactivity. Animals receiving the combined treatment showed a reduction in these adaptive effects on receptor binding and turnover relative to the individual agents, or even an effect in the opposite direction; further, normal sex differences in serotonin receptor concentrations were dissipated or reversed, an effect that was confirmed by behavioral evaluations in the Novel Objection Recognition Test. In addition to the known liabilities associated with maternal smoking during pregnancy, our results point to additional costs in the form of heightened vulnerability to neurotoxic chemicals encountered later in life.

Neurobehavioral evaluation of adolescent male rats following repeated exposure to chlorpyrifos

Chlorpyrifos (CPF), a highly effective organophosphate pesticide (OP), is extensively used worldwide. However, its agricultural use was extensively reduced in 2001. Several studies have suggested an association between mood disorders and CPF exposure in humans, especially in children, a subgroup that is highly susceptible to xenobiotics. We investigated the hypothesis that repeated CPF exposure in animals would elicit depressive-like behavioral alterations that reflected depression-related symptoms. Adolescent male rats were subcutaneously injected with either olive oil or 2.5, 5, 10, or 20mg/kg CPF from postnatal day 27 to 36, then were followed by a series of neurobehavioral evaluation. Our studies revealed depressive-like alterations that were manifested by increased despair behavior in the forced swimming test, increased escape failure in the learned helplessness test, and altered approach-avoidance conflict in the novelty-suppressed feeding test. There was no effect on locomotor activity in the open-field activity test. This study indicates that repeated exposure to CPF elicits depressive-like behavioral alterations in adolescent male rats.

Suicidal ideation and occupational pesticide exposure among male farmers

BACKGROUND

The occupation of farming has been reported to be associated with a high suicide rate, and suicidal ideation is an important risk factor for suicide. The objective of this study was to explore the association between occupational pesticide exposure or poisoning history and suicidal ideation among male farmers in South Korea.

METHODS

Through a nationwide sampling survey, a total of 1958 male farmers were interviewed in 2011 in South Korea. Detailed occupational pesticide exposure and pesticide poisoning information were obtained from face-to-face interviews. Suicidal ideation was defined as whether they had thought of harming themselves or trying to take their own lives over the preceding year. Logistic regression analyses were conducted to examine the effect of pesticide poisoning on suicidal ideation.

RESULTS

Among all farmers, 4.7% (n=92) reported suicidal ideation in 2010. After controlling for potential confounders, lifetime hospitalization due to pesticide poisoning showed a 2.48-fold increase in risk (95% CI: 1.26, 4.91). Those with multiple poisonings showed more significant associations with suicidal ideation (OR=2.33 for once, OR=3.02 for more than once). Moderate- or severe-symptom severity of acute pesticide poisoning cases (OR=2.23; 95% CI: 1.21-4.11) also showed increased risks of suicidal ideation than the milder classes did. However, no significant association was identified with cumulative lifetime pesticide application and suicidal ideation.

CONCLUSIONS

Our findings suggest that risk of suicidal ideation is related to occupational pesticide poisoning among male farmers.

Suicide and pesticide use among pesticide applicators and their spouses in the agricultural health study

BACKGROUND

An association may exist between pesticide exposure and suicide.

OBJECTIVE

We sought to evaluate the existence of an association between pesticide use and suicide using data from the Agricultural Health Study (AHS), a prospective cohort study of licensed pesticide applicators and their spouses in Iowa and North Carolina.

METHODS

Via linkage to state mortality files and the National Death Index, we identified 110 suicides occurring between enrollment in the AHS (from 1993 to 1997) and 31 May 2009, among 81,998 cohort members contributing 1,092,943 person-years of follow-up. The average length of follow-up was 13.3 years. AHS participants provided data on pesticide use and potential confounders via self-administered questionnaires at enrollment. We evaluated several measures of pesticide use: use of any pesticide, ever use of 50 specific pesticides, cumulative lifetime days of use and intensity-adjusted cumulative lifetime days of use of 22 specific pesticides, and ever use of 10 functional and chemical classes of pesticides. We used Cox proportional hazards regression models to estimate adjusted hazard ratios and 95% confidence intervals.

RESULTS

After adjusting for age at enrollment, sex, number of children in family, frequency of alcohol consumption during the past 12 months, and smoking status, we found no association between prior pesticide use and suicide in applicators and their spouses. Results were the same for applicators and spouses together or for applicators alone and were consistent across several measures of pesticide use.

CONCLUSIONS

Our findings do not support an association between moderate pesticide use and suicide.

Repeated exposure to chlorpyrifos alters the performance of adolescent male rats in animal models of depression and anxiety

Chlorpyrifos (CPF) is a broad spectrum, highly effective organophosphorus (OP) pesticide that has been largely used worldwide. Over the past decades, numerous studies have assessed the potential neurotoxic effects of either acute or chronic exposure to CPF on developing brain. Despite being an acetylcholinersterase inhibitor, the effects of CPF are not only confined to cholinergic system, but are involved in a wide variety of neurotransmitter systems, especially the serotonin (5-HT) system, which leads to long-lasting changes in 5-HT-related emotional behaviors. In our present study, 4-week-old adolescent male Sprague-Dawley rats were repeatedly exposed to CPF at daily doses of 10, 20, 40, 80, and 160 mg/kg/day (s.c., 7 days), and then subjected to a battery of emotional behavioral tests that related to serotonergic function in order to determine CPF effects in adolescent rats. Results in behavioral tests demonstrated CPF significantly increased the entries to and time spent in the open arms in the elevated plus-maze test at the dose of 40-160 mg/kg, the number of shocks in the Vogel's conflict test at the dose of 20-160 mg/kg, and significantly decreased the latency to feed in the novelty-suppressed feeding test in both dose range. Interestingly, in the forced swimming test, at the dose of 10mg/kg, CPF significantly increased the immobility time, whereas it significantly decreased the immobility time at the dose of 160 mg/kg. Our data suggest that repeated exposure to CPF elicits alterations of the emotional behaviors related to serotonergic nervous system in adolescent male rats. However, the underlying mechanism needs further investigations.

Air pollution and emergency department visits for suicide attempts in vancouver, Canada

BACKGROUND

Comorbidity of depression, heart disease, and migraine has been observed in clinical practice, while ambient air pollution has been identified among different risk factors for these health conditions. Suicide attempts and ideations as the result of depression may be linked to air pollution exposure. Therefore the effects of ambient air pollution on emergency department (ED) visits for suicide attempts were investigated.

METHODS

Emergency visit data were collected in a hospital in Vancouver, Canada. The generalized linear mixed models technique was applied in the analysis of these data. A natural hierarchical structure of the data was used to define the clusters, with days nested in a 3-level structure (day of week, month, year). Poisson models were fitted to the clustered counts of ED visits with a single air pollutant, temperature and relative humidity. In addition, the case-crossover methodology was used with the same data for comparison. The analysis was performed by gender (all, males, females) and month (all: January-December, warm: April-September, cold: October-March).

RESULTS

Both hierarchical and case-crossover methods confirmed positive and statistically significant associations among carbon monoxide (CO), nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)), and particulate matter (PM(10)) for all suicide attempts in the cold period. The largest increase was observed for males in the cold period for a 1-day lagged exposure to NO(2), with an excess risk of 23.9% (95% CI: 7.8, 42.4) and odds ratio of 1.21 (95% CI: 1.03, 1.41). In warm months the associations were not statistically significant, and the highest positive value was obtained for ozone lagged by 1 day.

CONCLUSION

The results indicate a potential association between air pollution and emergency department visits for suicide attempts.

A review of pesticide exposure and cancer incidence in the Agricultural Health Study cohort

OBJECTIVE

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort.

DATA SOURCES

Studies were identified from the AHS publication list available at http://aghealth.nci.nih.gov as well as through a Medline/PubMed database search in March 2009. We also examined citation lists. Findings related to lifetime-days and/or intensity-weighted lifetime-days of pesticide use are the primary focus of this review, because these measures allow for the evaluation of potential exposure-response relationships.

DATA SYNTHESIS

We reviewed 28 studies; most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios (or odds ratios) and positive exposure-response patterns were reported for 12 pesticides currently registered in Canada and/or the United States (alachlor, aldicarb, carbaryl, chlorpyrifos, diazinon, dicamba, S-ethyl-N,N-dipropylthiocarbamate, imazethapyr, metolachlor, pendimethalin, permethrin, trifluralin). However, estimates of association for specific cancers were often imprecise because of small numbers of exposed cases, and clear monotonic exposure-response patterns were not always apparent. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposure-response patterns. Epidemiologic evidence outside the AHS remains limited with respect to most of the observed associations, but animal toxicity data support the biological plausibility of relationships observed for alachlor, carbaryl, metolachlor, pendimethalin, permethrin, and trifluralin.

CONCLUSIONS

Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.

Effect of in vivo nicotine exposure on chlorpyrifos pharmacokinetics and pharmacodynamics in rats

Routine use of tobacco products may modify physiological and metabolic functions, including drug metabolizing enzymes, which may impact the pharmacokinetics of environmental contaminants. Chlorpyrifos is an organophosphorus (OP) insecticide that is bioactivated to chlorpyrifos-oxon, and manifests its neurotoxicity by inhibiting acetylcholinesterase (AChE). The objective of this study was to evaluate the impact of repeated nicotine exposure on the pharmacokinetics of chlorpyrifos (CPF) and its major metabolite, 3,5,6-trichloro-2-pyridinol (TCPy) in blood and urine and also to determine the impact on cholinesterase (ChE) activity in plasma and brain. Animals were exposed to 7-daily doses of either 1mg nicotine/kg or saline, and to either a single oral dose of 35mg CPF/kg or a repeated dose of 5mg CPF/kg/day for 7 days. Groups of rats were then sacrificed at multiple time-points after receiving the last dose of CPF. Repeated nicotine and CPF exposures resulted in enhanced metabolism of CPF to TCPy, as evidenced by increases in the measured TCPy peak concentration and AUC in blood. However, there was no significant difference in the amount of TCPy (free or total) excreted in the urine within the first 24-h post last dose. The extent of brain acetylcholinesterase (AChE) inhibition was reduced due to nicotine co-exposure consistent with an increase in CYP450-mediated dearylation (detoxification) versus desulfuration. It was of interest to note that the impact of nicotine co-exposure was experimentally observed only after repeated CPF doses. A physiologically based pharmacokinetic model for CPF was used to simulate the effect of increasing the dearylation V(max) based upon previously conducted in vitro metabolism studies. Predicted CPF-oxon concentrations in blood and brain were lower following the expected V(max) increase in nicotine treated groups. These model results were consistent with the experimental data. The current study demonstrated that repeated nicotine exposure could alter CPF metabolism in vivo, resulting in altered brain AChE inhibition.

Historical perspective of pesticide poisoning in Japan and measures taken by the Japanese association of rural medicine

The use of pesticides has rapidly increased in Japan since the end of World War II, significantly reducing work burdens and boosting food production. In the meantime, pesticides, responsible for poisoning and environmental pollution, have for many years posed grave issues that have had to be tackled by scientists of rural medicine for a long period. The Japanese Association of Rural Medicine, founded by the late Toshikazu Wakatsuki, has grappled with those issues for many years. Above all, the association has fulfilled its social obligations, such as by bringing the toxicity of organic mercury to light in animal tests to prompt the government to prohibit its use, and by casting light on birth defects caused by defoliants aerially sprayed during the Vietnam War to urge U.S. military forces to break off herbicide warfare. As it has become possible to make less toxic pesticides available for farm work in recent years, death-inducing accidents have seldom occurred during the spraying of pesticides, and the association’s activities are now at a low ebb. Now that pesticides, which after all are biologically toxic compounds, are openly used on farms, there is the need to pay constant attention to their impacts on the human body and the environment. In the future, it is necessary to epidemiologically probe into chronic impacts on the human body and contribute to the prevention of pesticide poisoning in Southeast Asia.

Neonatal parathion exposure disrupts serotonin and dopamine synaptic function in rat brain regions: modulation by a high-fat diet in adulthood

The consequences of exposure to developmental neurotoxicants are influenced by environmental factors. In the present study, we examined the role of dietary fat intake. We administered parathion to neonatal rats and then evaluated whether a high-fat diet begun in adulthood could modulate the persistent effects on 5HT and DA systems. Neonatal rats received parathion on postnatal days 1-4 at 0.1 or 0.2 mg/kg/day, straddling the cholinesterase inhibition threshold. In adulthood, half the animals in each exposure group were given a high-fat diet for 8 weeks. We assessed 5HT and DA concentrations and turnover in brain regions containing their respective cell bodies and projections. In addition, we monitored 5HT1A and 5HT2 receptor binding and the concentration of 5HT presynaptic transporters. Neonatal parathion exposure evoked widespread increases in neurotransmitter turnover, indicative of presynaptic hyperactivity, further augmented by 5HT receptor upregulation. In control rats, consumption of a high-fat diet recapitulated many of the changes seen with neonatal parathion exposure; the effects represented convergent mechanisms, since the high-fat diet often obtunded further increases caused by parathion. Neonatal parathion exposure causes lasting hyperactivity of 5HT and DA systems accompanied by 5HT receptor upregulation, consistent with "miswiring" of neuronal projections. A high-fat diet obtunds the effect of parathion, in part by eliciting similar changes itself. Thus, dietary factors may produce similar synaptic changes as do developmental neurotoxicants, potentially contributing to the increasing incidence of neurodevelopmental disorders.

Developmental neurotoxicity of parathion: progressive effects on serotonergic systems in adolescence and adulthood

Neonatal exposures to organophosphates that are not acutely symptomatic or that produce little or no cholinesterase inhibition can nevertheless compromise the development and later function of critical neural pathways, including serotonin (5HT) systems that regulate emotional behaviors. We administered parathion to newborn rats on postnatal days (PN) 1-4 at doses spanning the threshold for detectable cholinesterase inhibition (0.1 mg/kg/day) and the first signs of loss of viability (0.2 mg/kg/day). In adolescence (PN30), young adulthood (PN60) and full adulthood (PN100), we measured radioligand binding to 5HT(1A) and 5HT(2) receptors, and to the 5HT transporter in the brain regions comprising all the major 5HT projections and 5HT cell bodies. Parathion caused a biphasic effect over later development with initial, widespread upregulation of 5HT(1A) receptors that peaked in the frontal/parietal cortex by PN60, followed by a diminution of that effect in most regions and emergence of deficits at PN100. There were smaller, but statistically significant changes in 5HT(2) receptors and the 5HT transporter. These findings stand in strong contrast to previous results with neonatal exposure to a different organophosphate, chlorpyrifos, which evoked parallel upregulation of all three 5HT synaptic proteins that persisted from adolescence through full adulthood and that targeted males much more than females. Our results support the view that the various organophosphates have disparate effects on 5HT systems, distinct from their shared property as cholinesterase inhibitors, and the targeting of 5HT function points toward the importance of studying the impact of these agents on 5HT-linked behaviors.

Developmental neurotoxicants target neurodifferentiation into the serotonin phenotype: Chlorpyrifos, diazinon, dieldrin and divalent nickel

Developmental exposure to organophosphates (OP) produces long-term changes in serotonin (5HT) synaptic function and associated behaviors, but there are disparities among the different OPs. We contrasted effects of chlorpyrifos and diazinon, as well as non-OP neurotoxicants (dieldrin, Ni(2+)) using undifferentiated and differentiating PC12 cells, a well-established neurodevelopmental model. Agents were introduced at 30 microM for 24 or 72 h, treatments devoid of cytotoxicity, and we evaluated the mRNAs encoding the proteins for 5HT biosynthesis, storage and degradation, as well as 5HT receptors. Chlorpyrifos and diazinon both induced tryptophan hydroxylase, the rate-limiting enzyme for 5HT biosynthesis, but chlorpyrifos had a greater effect, and both agents suppressed expression of 5HT transporter genes, effects that would tend to augment extracellular 5HT. However, whereas chlorpyrifos enhanced the expression of most 5HT receptor subtypes, diazinon evoked overall suppression. Dieldrin evoked even stronger induction of tryptophan hydroxylase, and displayed a pattern of receptor effects similar to that of diazinon, even though they come from different pesticide classes. In contrast, Ni(2+) had completely distinct actions, suppressing tryptophan hydroxylase and enhancing the vesicular monoamine transporter, while also reducing 5HT receptor gene expression, effects that would tend to lower net 5HT function. Our findings provide some of the first evidence connecting the direct, initial mechanisms of developmental neurotoxicant action on specific transmitter pathways with their long-term effects on synaptic function and behavior, while also providing support for in vitro test systems as tools for establishing mechanisms and outcomes of related and unrelated neurotoxicants.

Developmental neurotoxicity of low dose diazinon exposure of neonatal rats: effects on serotonin systems in adolescence and adulthood

The developmental neurotoxicity of organophosphate pesticides targets serotonin (5HT) systems, which are involved in emotional and appetitive behaviors. We exposed neonatal rats to daily doses of diazinon on postnatal days 1-4, using doses (0.5 or 2mg/kg) spanning the threshold for barely-detectable cholinesterase inhibition. We then evaluated the effects on 5HT(1A) and 5HT(2) receptors, and on the 5HT transporter in cerebral cortical regions and the brainstem in adolescence through adulthood. Diazinon evoked a lasting deficit in 5HT(1A) receptors in males only, whereas it caused a small but significant increase in 5HT transporters in females; neither effect showed a significant regional selectivity. This pattern differed substantially from that seen in earlier work with another organophosphate, chlorpyrifos, which at pharmacodynamically similar doses spanning the threshold for cholinesterase inhibition, evoked a much more substantial, global upregulation of 5HT receptor expression; with chlorpyrifos, effects on receptors were seen in females, albeit to a lesser extent than in males, and were also regionally distinct. The effects of diazinon were nonmonotonic, showing larger alterations at the lower dose, likely reflecting positive trophic effects of cholinergic stimulation once the threshold for cholinesterase inhibition is exceeded. Our results reinforce the idea that different organophosphates have fundamentally distinct effects on the developmental trajectories of specific neurotransmitter systems, unrelated to their shared action as cholinesterase inhibitors. The effects on 5HT circuits expand the scope of behavioral endpoints that need to be considered in evaluating the developmental neurotoxicity of organophosphates.