Community exposure to a paraquat drift

Agricultural paraquat dichloride use and Parkinson's disease in California's Central Valley

BACKGROUND

Paraquat dichloride is currently among the most widely used commercial herbicides in the USA. In the present study, we provide epidemiological assessment of ambient paraquat exposure and Parkinson's disease (PD) risk in a population-based study of PD in agricultural regions of Central California.

METHODS

Based on 829 PD patients and 824 community controls, we assessed associations between ambient paraquat dichloride exposure and PD. We estimated residential and workplace proximity to commercial agricultural applications in three California counties since 1974 using the CA pesticide use reporting (PUR) data and land use maps. We evaluated any, duration and average intensity [pounds (0.45 kilograms) per acre per year] of exposure for paraquat in four time windows.

RESULTS

Ambient paraquat exposure assessed at both residence and workplace was associated with PD, based on several different exposure measures. The PD patients both lived and worked near agricultural facilities applying greater amounts of the herbicide than community controls. For workplace proximity to commercial applications since 1974, working near paraquat applications every year in the window [odds ratio (OR) = 2.15, 95% confidence interval (CI) = 1.46, 3.19] and a higher average intensity of exposure [per 10 pounds (4.54 kilograms), OR = 2.08, 95% CI = 1.31, 3.38] were both associated with an increased odds of PD. Similar associations were observed for residential proximity (duration: OR = 1.91, 95% CI = 1.30, 2.83; average intensity: OR = 1.72, 95% CI = 0.99, 3.04). Risk estimates were comparable for men and women, and the strongest odds were observed for those diagnosed at ≤60 years of age.

CONCLUSION

This study provides further indication that paraquat dichloride exposure increases the risk of Parkinson's disease.

Paraquat Inhalation, a Translationally Relevant Route of Exposure: Disposition to the Brain and Male-Specific Olfactory Impairment in Mice

Epidemiological and experimental studies have associated oral and systemic exposures to the herbicide paraquat (PQ) with Parkinson's disease. Despite recognition that airborne particles and solutes can be directly translocated to the brain via olfactory neurons, the potential for inhaled PQ to cause olfactory impairment has not been investigated. This study sought to determine if prolonged low-dose inhalation exposure to PQ would lead to disposition to the brain and olfactory impairment, a prodromal feature of Parkinson's disease. Adult male and female C57BL/6J mice were exposed to PQ aerosols in a whole-body inhalation chamber for 4 h/day, 5 days/week for 4 weeks. Subsets of mice were sacrificed during and after exposure and PQ concentrations in various brain regions (olfactory bulb, striatum, midbrain, and cerebellum) lung, and kidney were quantified via mass spectrometry. Alterations in olfaction were examined using an olfactory discrimination paradigm. PQ inhalation resulted in an appreciable burden in all examined brain regions, with the highest burden observed in the olfactory bulb, consistent with nasal olfactory uptake. PQ was also detected in the lung and kidney, yet PQ levels in all tissues returned to control values within 4 weeks post exposure. PQ inhalation caused persistent male-specific deficits in olfactory discrimination. No effects were observed in females. These data support the importance of route of exposure in determination of safety estimates for neurotoxic pesticides, such as PQ. Accurate estimation of the relationship between exposure and internal dose is critical for risk assessment and public health protection.

Delayed death following paraquat poisoning: three case reports and a literature review

Paraquat (PQ) poisoning is principally reported in developing countries. However, most fatalities occur elsewhere due to the induction of multi-organ failure. PQ poisoning can hardly be managed by clinical practice, and no specific antidote has come into existence yet. Here three cases, including 17-, 20-, and 23-year-old men, who were poisoned with PQ, have been reported. Furthermore, the literature regarding biological mechanisms, clinical manifestation, and treatment of PQ-induced toxicity was reviewed. Patients who, either intentionally or accidentally, ingested PQ earlier were initially found to be stable at the emergency department (ED). Therefore, they were discharged from the hospital under a follow-up. However, after several days, the patients were referred to the hospital for the second time and despite cardiovascular resuscitation (CPR) efforts, they suddenly expired. The delayed death following exposure to PQ was reported for inducing gradual progressive pulmonary fibrosis, metabolic acidosis, neurotoxicity, renal failure, and liver injury in poisoned patients. Therefore, PQ-intoxicated patients should be supervised for up to several weeks, and kept in the hospital for a longer period of time. Clinical manifestations and laboratory findings are beneficial markers that act as useful predictors of PQ poisoning.

Environmental exposure to pesticides and respiratory health

Respiratory effects of environmental exposure to pesticides are debated. Here we aimed to review epidemiological studies published up until 2013, using the PubMed database. 20 studies dealing with respiratory health and non-occupational pesticide exposure were identified, 14 carried out on children and six on adults. In four out of nine studies in children with biological measurements, mothers' dichlorodiphenyldichloroethylene (DDE) blood levels during pregnancy were associated with asthma and wheezing in young children. An association was also found between permethrin in indoor air during pregnancy and wheezing in children. A significant association between asthma and DDE measured in children's blood (aged 7-10 years) was observed in one study. However, in three studies, no association was found between asthma or respiratory infections in children and pesticide levels in breast milk and/or infant blood. Lastly, in three out of four studies where post-natal pesticide exposure of children was assessed by parental questionnaire an association with respiratory symptoms was found. Results of the fewer studies on pesticide environmental exposure and respiratory health of adults were much less conclusive: indeed, the associations observed were weak and often not significant. In conclusion, further studies are needed to confirm whether there is a respiratory risk associated with environmental exposure to pesticides.

Living near agricultural pesticide applications and the risk of adverse reproductive outcomes: a review of the literature

Over the last decade, there has been growing concern about the possible health effects, including a number of adverse reproductive outcomes, from pesticide exposure of people living near agricultural fields. This systematic review evaluates the current epidemiological evidence on the association between living near agricultural pesticide applications and adverse reproductive outcomes, including congenital malformations, stillbirth, intrauterine growth retardation (IUGR), low birthweight, preterm birth and miscarriage. We identified and reviewed 25 studies from a systematic search of the main scientific databases and other sources published in 1950-2007. Study methods and main results were summarised and tabulated according to the year of study, design and type of adverse reproductive outcome. The levels of evidence for reproductive toxicity in humans contributed by each study were assessed and the main limitations associated with these studies discussed. Residential proximity to agricultural pesticide applications may be an important source of ambient environmental exposure, but because of the underlying methodological difficulties, the strength of evidence for its relationship with adverse reproductive outcomes is generally weak and varied between outcomes. The evidence suggested an association for congenital malformations, but because of methodological limitations, such as poor exposure measurement and potentially inadequate control of confounding, a firm conclusion remains beyond reach. For the other outcomes (stillbirth, IUGR, low birthweight, preterm birth and miscarriage) the evidence for any associations was equivocal at best, but some leads warrant further investigation. Improved exposure assessment methods are needed to obtain a more reliable assessment of any risks.

Lupus erythematosus. Are residential insecticides exposure the missing link?

Although the etiology of systemic lupus erythematosus (SLE) remains to be fully elucidated, it is now apparent that multiple genetic and environmental factors are at play. Because lupus has a strong female preponderance, several studies have examined the role of female hormones in disease etiology. Yet this knowledge has not helped to explain lupus etiology or to prevent it. Estrogens exist not only as natural or drug compounds, but also as environmental chemical contaminant and women are highly exposed to all of them. Estrogenic activity has been found in a number of pesticides including pyrethroids that are largely used in the household. Although there is only a small amount of published data examining a possible causal relationship between lupus and pesticides it can be hypothesized that pesticides, in particular insecticides, through their estrogenic activity and capacity to induce oxidative stress provoke autoimmune reaction influencing lupus development.

Semen quality in Peruvian pesticide applicators: association between urinary organophosphate metabolites and semen parameters

BACKGROUND

Organophosphates are broad class of chemicals widely used as pesticides throughout the world. We performed a cross-sectional study of associations between dialkylphosphate metabolites of organophosphates and semen quality among pesticide applicators in Majes (Arequipa), Peru.

METHODS

Thirty-one men exposed to organophosphate (OP) pesticides and 31 non-exposed were recruited (age, 20-60 years). In exposed subjects, semen and a blood sample were obtained one day after the last pesticide application. Subjects were grouped according to levels of OP metabolites in urine. Semen samples were analyzed for sperm concentration, percentage of sperm motility, percentage of normal morphology, semen leucocytes and concentrations of fructose and zinc. Exposure to OP was assessed by measuring six urinary OP metabolites (dimethyl and diethyl phosphates and thiophosphates) by gas chromatography using a single flame photometric detector.

RESULTS

Diethyldithiophosphate (p = 0.04) and diethylthiophosphate (p = 0.02) better reflected occupational pesticide exposure than other OP metabolites. Semen analysis revealed a significant reduction of semen volume and an increase in semen pH in men with OP metabolites. Multiple regression analysis showed that both occupational exposure to pesticides and the time of exposure to pesticides were more closely related to alterations in semen quality parameters than the single measurement of OP metabolites in urine.

CONCLUSION

The study demonstrated that occupational exposure to OP pesticides was more closely related to alterations in semen quality than a single measurement of urine OP metabolites. Current measurement of OP metabolites in urine may not reflect the full risk.

Prolonged toxicokinetics and toxicodynamics of paraquat in mouse brain

BACKGROUND

Paraquat (PQ) has been implicated as a risk factor for the Parkinson disease phenotype (PDP) in humans and mice using epidemiologic or experimental approaches. The toxicokinetics (TK) and toxicodynamics (TD) of PQ in the brain are not well understood.

OBJECTIVES

The TK and TD of PQ in brain were measured after single or repeated doses.

METHODS

Brain regions were analyzed for PQ levels, amount of lipid peroxidation, and functional activity of the 20S proteasome.

RESULTS

Paraquat (10 mg/kg, ip) was found to be persistent in mouse ventral midbrain (VM) with an apparent half-life of approximately 28 days and was cumulative with a linear pattern between one and five doses. PQ was also absorbed orally with a concentration in brain rising linearly after single doses between 10 and 50 mg/kg. The level of tissue lipid peroxides (LPO) was differentially elevated in three regions, being highest in VM, lower in striatum (STR), and least in frontal cortex (FCtx), with the earliest significant elevation detected at 1 day. An elevated level of LPO was still present in VM after 28 days. Despite the cumulative tissue levels of PQ after one, three, and five doses, the level of LPO was not further increased. The activity of the 20S proteasome in the striatum was altered after a single dose and reduced after five doses.

CONCLUSIONS

These data have implications for PQ as a risk factor in humans and in rodent models of the PDP.

Biological monitoring of pesticide exposures among applicators and their children in Nicaragua

Exposures were assessed for seven small-scale farmers using chlorpyrifos on corn and ten banana plantation employees applying diazinon, and for one child of each worker. Metabolites (TCPYand IMPY) were measured in urine before and after applications. TCPY concentrations peaked at 27 and 8.5 hours post-application for applicators and children, respectively (geometric means, 26 and 3.0 microg/L). Proximity to spraying and spray mixture preparation in homes were important exposure factors. IMPY concentrations differed substantially across workers at two plantations (geometric means, 1.3 and 168 mirog/L); however, their children had little or no diazinon exposure. These workers and children were also exposed to chlorpyrifos, most likely through contact with chlorpyrifos-impregnated bags used in banana production. Several recommendations are offered: (1) monitor children's activities during applications; (2) do not store or prepare pesticides in homes; (3) institute sound occupational hygiene practices at banana plantations; (4) dispose of plastic insecticide bags properly at the worksite.

Chronic bronchitis and pesticide exposure: a case–control study in Lebanon

OBJECTIVE

Pesticides are widely used toxics. The objective of the study is to evaluate the odds of exposure to pesticides in chronic bronchitis patients.

METHODS

Using the American Thoracic Society standardized questionnaire confirmed by medical diagnosis of chronic bronchitis, a case-control study was performed in Lebanon. Pesticide exposure was estimated and between groups comparison was made.

RESULTS

The study involved 262 controls and 110 chronic bronchitis outpatient subjects from 10 medical centers. Any exposure to pesticides was associated to chronic bronchitis (OR = 2.46 [1.53-3.94]; p < 10(-4)). Occupational use presented the highest association (15.92 [3.50-72.41]; p < 10(-4)), followed by regional exposure (3.70 [2.05-6.70]; p < 10(-4)). Results were confirmed by multivariate and subgroup analysis.

CONCLUSION

Pesticide exposure was associated with chronic bronchitis in Lebanese adults. Pesticides toxicological effects may explain chronic respiratory effects associations found with all exposure types.

Respiratory diseases and pesticide exposure: a case-control study in Lebanon

STUDY OBJECTIVE

To evaluate the odds of being exposed to pesticides in asthmatic adults.

DESIGN

A case-control study was performed in Lebanon.

SETTING

People were approached when consulting physicians as outpatients.

PATIENTS

Asthmatic patients and non-asthmatic controls in several Lebanese hospitals were interviewed.

MAIN RESULTS

The study included 407 subjects from 10 medical centres. Any exposure to pesticides was associated to asthma (OR = 2.11 (1.47 to 3.02); p<10(-4)). Occupational use presented the highest association (OR = 4.98 (1.07 to 23.28); p = 0.02), followed by regional exposure (OR 3.51 (2.11 to 5.85); p<10(-4)). Results were confirmed by multivariate analysis, particularly for regional exposure (OR(a) = 2.78; p = 0.02) and house exposure (OR(a) = 2.17; p = 0.001).

CONCLUSIONS

Results are comparable to those found in other studies; especially for occupational exposure. Pesticides toxicological effects may explain chronic respiratory symptoms and asthma associations found with all exposure types. Pesticide exposure was associated with asthma in Lebanese adults.

The Washington aerial spray drift study: children's exposure to methamidophos in an agricultural community following fixed-wing aircraft applications

This study characterized exposures of eight children living in an agricultural community near potato fields that were treated by aerial application with the organophosphorus (OP) insecticide, methamidophos (O,S-dimethyl phosphoramidothioate). Exposure monitoring included air and deposition samples in the outdoor community environment, outdoor and indoor air samples at each residence, wipe samples of playground equipment, toys, indoor surfaces, and children's hands, and periodic urine samples. Monitoring occurred prior to, the day of, and 1 day following applications. Methamidophos deposition in the community was very low compared to deposition inside the boundaries of the treated fields. Community air concentrations increased from 0.05 microg/m3 (prespray) to 0.11 and 0.48 microg/m3 (spray day morning and afternoon, respectively), decreasing to 0.10 microg/m3 on the postspray day. Air concentrations outside residences followed a similar pattern; indoor levels did not exceed 0.03 pg/m3. Methamidophos residues were found on playground equipment following applications, but not on indoor residential surfaces. The median hand wipe levels increased from < 0.02 (prespray) to 0.08 microg/sample (spray day), decreasing to 0.05 microg/sample (postspray day). Median concentrations of the primary methamidophos urinary metabolite were 61 microg/l before 1100 hours on the spray day, 170 microg/l after 1100 hours on the spray day, and 114 microg/l on the postspray day. Spray day metabolite levels were correlated with time outside on the spray day (rs = 0.68), with spray day hand wipe levels (rs = 0.67), and with postspray day metabolite levels (rs = 0.64). Postspray day metabolites levels were also positively associated with postspray day hand wipe levels (rs = 0.66). The documentation of children's exposure in this study does not necessarily mean that risks for these children were significantly altered, since nearly all children in the United States are exposed to some level of OP pesticides through dietary intake and other pathways. The association of metabolite levels with time spent outside, and the absence of methamidophos in homes indicates that children's exposures occurred primarily outdoors.

A Fetal Risk Factor for Parkinson’s Disease

A lack of strong evidence for genetic heritability of idiopathic Parkinson's disease (PD) has focused attention on environmental toxicants in the disease etiology, particularly agrichemicals. PD is associated with advanced age, but it is unclear whether specific neuronal damage could result from insults during development. This study hypothesized that prenatal exposure to pesticides would disrupt the development of the nigrostriatal dopamine (DA) system and enhance its vulnerability to dopaminergic neurotoxicant exposures later in life. Pregnant C57BL/6J mice were treated on gestational days 10-17 with saline or the pesticides maneb (MB, 1 mg/kg) or paraquat (PQ, 0.3 mg/kg). When offspring were evaluated in adulthood, there were no significant effects of prenatal MB or PQ exposure on locomotor activity. Subsequently, offspring were treated for 8 consecutive days with saline, MB (30 mg/kg), or PQ (5 mg/kg). One week after the last exposure, only males exposed to prenatal MB and adulthood PQ showed significant reductions in locomotor activity (95%) and changes in striatal neurochemistry. Stereological assessment of the substantia nigra pars compacta (SNpc) and ventral tegmental area correspondingly confirmed selective dopaminergic-neuron loss in SNpc. The lack of changes in other exposure groups suggests a specificity to the sequence of exposures as well as gender specificity. These results suggest that prenatal exposure to MB produces selective, permanent alterations of the nigrostriatal dopaminergic system and enhances adult susceptibility to PQ exposure. This study implicates a role for developmental neurotoxicant exposure in the induction of neurodegenerative disorders such as PD.

Interactions of Paraquat and Triadimefon: Behavioral and Neurochemical Effects

Triadimefon (TDF), a triazole fungicide, and paraquat (PQ), a non-selective herbicide/dessicant, are both known to adversely impact brain dopaminergic function and are used in overlapping geographical areas of the US. Since "real world" situations indicate humans are exposed to a diverse mixture of chemicals, this study hypothesized that combined exposures to PQ+TDF could produce interactive effects by simultaneously attacking multiple target sites of dopamine systems. Thus, 10 mg/kg PQ (PQ10) and 25 or 50 mg/kg TDF (TDF25 and 50, respectively) were administered i.p. to male C57BL/6 mice, 2x per week for 12 weeks, either alone or in combination. Acutely, TDF50 increased horizontal and vertical activity with increased vertical activity still occurring 24h later, indicative of sustained behavioral sensitization. Acutely, PQ decreased horizontal but not vertical activity with a lack of residual effects at 24h. PQ prevented the increased levels of activity associated with TDF50. These interactions differed for horizontal and vertical activity, indicating their differential neurochemical mediation, and suggesting that they did not arise from simple additivity of PQ and TDF effects. Nor could the interactive effects be readily ascribed to corresponding neurochemical interactions, since all treatments generally increased levels of DA and metabolites acutely in striatum and were associated with general reductions in levels of DA and metabolites and turnover in striatum and frontal cortex 7 days after the final treatment. Thus, TDF and PQ both separately and through interactions may serve as environmental risk factors through different mechanisms for dopaminergically-mediated behavioral dysfunctions.

A pilot study of global positioning system/geographical information system measurement of residential proximity to agricultural fields and urinary organophosphate metabolite concentrations in toddlers

This pilot study enrolled 20 children between the ages of 11 and 17 months in Imperial County, California to assess children's pesticide exposure and residential proximity to agricultural fields. We compared parental self-report of residential proximity to agricultural fields to measurements using global positioning system/geographical information system (GPS/GIS) technology, and we assessed the relationship between residential proximity to agricultural fields and a biomarker of organophosphate (OP) pesticide exposure. Questionnaires were administered twice, 4 weeks apart, to determine self-reported residential proximity to agricultural fields. Urine samples were collected at each contact to measure OP metabolites. Actual residential proximity to the closest agricultural field and number of fields was within 1 mile to the west were measured using GPS/GIS. Self-report of living proximity to agricultural fields agreed with GPS/GIS measurement 75% of the time during the initial interview, compared to 66% agreement during the second interview. Presence of urinary metabolites suggests that OP exposure was ubiquitous: creatinine-adjusted total urinary dimethyl values ranged from 1.60 to 516.00 microg/g creatinine, and total diethyl ranged from 2.70 to 134.84 microg/g creatinine. No association was found between urinary OP metabolites and residential to field proximity. These results suggest that initial self-report of living proximity to agricultural fields may be more accurate than follow-up self-report. Limitations in this pilot study prevent determination of whether self-report is an accurate measure of proximity.

Pesticide impacts on communities and schools

Early efforts directed toward the development of pesticide regulations addressed serious acute illnesses associated with pesticide mixing, loading, and application. As those pesticide exposures and illnesses came under control through official regulatory action, attention has turned toward problems associated with the impacts of pesticides on communities and schools. By contrast to the early successes in bringing major acute poisoning under control, the problems of pesticide impacts on communities and schools have been especially difficult to resolve through the regulatory process. This article discusses the dynamics of the new and emerging impacts of pesticides on communities and schools, with an emphasis upon California experiences.

Prevalence of non-specific health symptoms in South Australia

Non-specific health symptoms are commonly reported in communities exposed to environmental hazards. However these symptoms commonly occur in the general community as a result of lifestyle factors, illness such as cold and allergy, medical treatment, in addition to environmental and occupational exposures. This paper describes the prevalence of non-specific health symptoms in South Australia. A cross-sectional survey of 3016 persons aged 15 years and over across the State was undertaken. Stuffy nose was the most commonly reported symptoms, with a 2-week prevalence of 46%. Headaches, unusual tiredness, cough, sore throat and itchy eyes were each experienced by at least one in five persons in the previous 2-week period. Symptom reporting was greater among females compared with males and higher in younger age groups. These rates provide a useful reference for rates normally found in a community exposed to a broad range of personal, environmental and occupational factors that may lead to these symptoms.

A comparison of the prevalence of respiratory illness and non-specific health symptoms in two Victorian cities

OBJECTIVE

To compare the prevalence of respiratory illness and non-specific health symptoms among adults and children aged 4-15 years living in Portland and Warrnambool, Victoria.

METHODS

A postal survey of 3,903 adults in Portland and Warrnambool systematically selected from the electoral roll was undertaken. Both an adults and children's questionnaire were enclosed in the mailing to each adult. If there were children aged 4-15 years in the household, an adult was asked to complete a questionnaire for the child who would next celebrate a birthday. Questionnaires were returned by 2,111 adults (54%) and for 585 children.

RESULTS

No significant differences in the prevalence of self-reported asthma or wheeze were observed among adults or children residing in Portland and Warrnambool. The likelihood of itchy eyes, skin rash and stuffy nose was significantly higher in Portland adults and children compared with those in Warrnambool. Dry cough at night was increased among Portland children, but not significantly so.

CONCLUSIONS

Higher rates of non-specific symptoms were observed in Portland but from a cross-sectional survey such as this, it is not possible to identify the cause of these higher rates. They may be related to environmental factors such as pollens or emissions from aluminium production, fertiliser production or bulk handling activities on the wharf, or they may be attributable to other factors such as response or recall bias.

The nigrostriatal dopaminergic system as a preferential target of repeated exposures to combined paraquat and maneb: implications for Parkinson's disease

Experimental evidence supporting 1,1'-dimethyl-4,4'-bipyridinium [paraquat (PQ)] as a risk factor for Parkinson's disease (PD) is equivocal. Other agricultural chemicals, including dithiocarbamate fungicides such as manganese ethylenebisdithiocarbamate [maneb (MB)], are widely used in the same geographical regions as paraquat and also impact dopamine systems, suggesting that mixtures may be more relevant etiological models. This study therefore proposed that combined PQ and MB exposures would produce greater effects on dopamine (DA) systems than would either compound administered alone. Male C57BL/6 mice were treated twice a week for 6 weeks with intraperitoneal saline, 10 mg/kg paraquat, 30 mg/kg maneb, or their combination (PQ + MB). MB, but not PQ, reduced motor activity immediately after treatment, and this effect was potentiated by combined PQ + MB treatment. As treatments progressed, only the combined PQ + MB group evidenced a failure of motor activity levels to recover within 24 hr. Striatal DA and dihydroxyphenylacetic acid increased 1-3 d and decreased 7 d after injections. Only PQ + MB reduced tyrosine hydroxylase (TH) and DA transporter immunoreactivity and did so in dorsal striatum but not nucleus accumbens. Correspondingly, striatal TH protein levels were decreased only by combined PQ + MB 5 d after injection. Reactive gliosis occurred only in response to combined PQ + MB in dorsal-medial but not ventral striatum. TH immunoreactivity and cell counts were reduced only by PQ + MB and in the substantia nigra but not ventral tegmental area. These synergistic effects of combined PQ + MB, preferentially expressed in the nigrostriatal DA system, suggest that such mixtures could play a role in the etiology of PD.

Biomarkers of exposure to organophosphorous insecticides among farmers' families in rural El Salvador: factors associated with exposure

Most studies of the health effects of pesticides have concentrated on occupational exposure. Little is known about community environmental exposure to agricultural pesticides. The purpose of this study was to investigate nonoccupational pesticide exposure among farmers' families in rural El Salvador, a country known for intensive use of extremely toxic compounds. The study population included all residents 8 years and older living in five agricultural communities in El Salvador. Current exposure to organophosphate insecticides (OPs) was established through analysis of urine samples for alkyl phosphate metabolites of OPs. Nearly half of 358 analyzed samples had detectable levels of OP metabolities. Of subjects not performing agricultural fieldwork, 30% nonetheless excreted detectable levels of metabolities. Similar rates held for children and adults. The best independent predictors for an individual's excretion of OP metabolites were (a) performing fieldwork during the past 2 weeks, (b) the head household farmer's application of OPs during the past 2 years, and (c) the household mother reporting use of OPs in the home or yard. The latter factors were significantly associated with metabolite excretion regardless of whether the individual had done fieldwork. The results of this study support the hypothesis that a large proportion of rural Salvadorans, including children, is exposed to pesticides through environmental as well as occupational routes.

Acute health effects associated with nonoccupational pesticide exposure in rural El Salvador

Little is known about the health effects of nonoccupational pesticide exposure in agricultural communities of poor countries. Therefore, this study investigated acute symptoms associated with nonoccupational exposure to organophosphate insecticides (OPs) in rural El Salvador, a region known for intensive pesticide use. In the five communities studied, 2-week prevalences of several acute symptoms were associated with living with a farmer who had recently applied methyl parathion. These included cramps in limbs (odds ratio 2.1, 95% confidence interval 1.2-3.7), chest pressure (OR 2.3, 95% CI 1.3-4.0), change in defecation (OR 2.3, 95% CI 1.3-4.1), feeling dazed (OR 2.4, 95% CI 1.3-4.4), and eyes tearing (OR 2.5, 95% CI 1. 4-4.5). Associations were found regardless of whether the individuals reporting the symptoms had themselves performed field labor. These results suggest that living in areas where pesticides are used on crops may represent an environmental health concern, especially for children.

Symptoms and cholinesterase activity among rural residents living near cotton fields in Nicaragua

OBJECTIVES

To explore whether symptoms resulted from pesticide spray drift on residentially exposed populations in rural Nicaragua.

METHODS

100 residents, each 10 years of age or older, were randomly selected from a Nicaraguan community surrounded by actively sprayed cotton fields (the exposed community) and from a socioeconomically similar community far from agricultural spraying (the control community). Subjects working with pesticides were excluded, and the study was conducted at the end of the 1990 cotton spraying season (August-December). Demographic information, exposure questions, and prevalence of 11 acute symptoms and 17 chronic symptoms were gathered from a structured interview. Finger stick erythrocyte cholinesterase (AChE) was measured with a portable colorimeter. Acute symptoms were grouped according to their previously known associations with cholinesterase (ChE) inhibitors into four ordinal categories (asymptomatic, non-specific, possible, probable).

RESULTS

Residents from the exposed community were significantly more likely to report recently sighting a spray plane near their community, exposure to pesticide from drift, crossing recently sprayed fields, eating home grown food, and feeling ill after drift exposure. The mean AChE value was significantly lower for residents of the exposed community (4.9 v 5.3 IU/dl). The proportion of subjects complaining of one or more chronic or acute symptoms was significantly higher for the exposed community (87%) than for the controls (53%). Odds ratios for residents in the exposed community, by symptom categories, were non-specific 1.6 (95% confidence interval (95% CI) 0-8 to 3.2), possible 4.1 (95% CI 1.7 to 10.2), and probable 9.93 (95% CI 2-9 to 34.4).

CONCLUSION

These findings indicate a strong association between exposure to aerial pesticides and symptoms. This study should be replicated with more quantitative exposure measures, for if confirmed, the results have relevance for millions in rural communities worldwide.

Risk factors for occupational illnesses associated with the use of paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride) in California

This study was conducted to identify risk factors for paraquat-related occupational illnesses. Pesticide-related illness is a reportable disease in California. A total of 231 skin (26.0%), eye (32.0%), local respiratory (3.5%), and systemic (38.5%) paraquat-related cases were reported to the Worker Health and Safety Branch, California Department of Food and Agriculture, during 1971 through 1985. Following paraquat exposure, we found no cases of pulmonary fibrosis. Annual numbers of cases ranged between 1 and 33 (median = 14 cases/y). Information on illnesses reported during 1981 through 1985 (n = 62) was merged with detailed information on paraquat use in agricultural settings (111,716 applications) for the same years. We found that crop treated, method of application, and season of application all contributed independently to the risk of reported illness. Hand application was associated with a higher risk of illness, compared with air application (RR = 99.1, 95% CI = 22.16-443.47); summer application was associated with a higher risk of illness than was winter application (RR = 4.1, 95% CI = 1.91-8.61); and fruit trees were associated with higher risk of illness than were other crops (mainly cotton) (RR = 3.6, 95% CI = 1.18-11.21).

Mitochondrial bioenergetics is affected by the herbicide paraquat

The potential toxicity of the herbicide paraquat (1,1-dimethyl-4,4'-bipyridylium dichloride) was tested in bioenergetic functions of isolated rat liver mitochondria. Paraquat increases the rate of State 4 respiration, doubling at 10 mM, indicating uncoupling effects. Additionally, State 3 respiration is depressed by about 15%, at 10 mM paraquat, whereas uncoupled respiration in the presence of CCCP is depressed by about 30%. Furthermore, paraquat partially inhibits the ATPase activity through a direct effect on this enzyme complex. However, at high concentrations (5-10 mM), the ATPase activity is stimulated, probably as consequence of the described uncoupling effect. Depression of respiratory activity is mediated through partial inhibitions of mitochondrial complexes III and IV. Paraquat depresses delta psi as a function of herbicide concentration. In addition, the depolarization induced by ADP is decreased and repolarization is biphasic suggesting a double effect. Repolarization resumes at a level consistently higher than the initial level before ADP addition, for paraquat concentrations up to 10 mM. This particular effect is clear at 1 mM paraquat and tends to fade out with increasing concentrations of the herbicide.