Structural Equation Modeling of Pesticide Poisoning,Depression, Safety,and Injury

ABSTRACT

The role of pesticide poisoning in risk of injuries may operate through a link between pesticide-induced depressive symptoms and reduced engagement in safety behaviors. The authors conducted structural equation modeling of cross-sectional data to examine the pattern of associations between pesticide poisoning, depressive symptoms, safety knowledge, safety behaviors, and injury. Interviews of 1637 Colorado farm operators and their spouses from 964 farms were conducted during 1993–1997. Pesticide poisoning was assessed based on a history of ever having been poisoned. The Center for Epidemiologic Studies—Depression scale was used to assess depressive symptoms. Safety knowledge and safety behaviors were assessed using ten items for each latent variable. Outcomes were safety behaviors and injuries. A total of 154 injuries occurred among 1604 individuals with complete data. Pesticide poisoning, financial problems, health, and age predicted negative affect/somatic depressive symptoms with similar effect sizes; sex did not. Depression was more strongly associated with safety behavior than was safety knowledge. Two safety behaviors were significantly associated with an increased risk of injury. This study emphasizes the importance of financial problems and health on depression, and provides further evidence for the link between neurological effects of past pesticide poisoning on risk-taking behaviors and injury.     

Structural Equation Modeling of the Relationships Between Pesticide Poisoning,Depressive Symptoms and Safety Behaviors Among Colorado Farm Residents

Abstract

Purpose: To use structural equation modeling (SEM) to test the theory that a past pesticide poisoning may act as a mediator in the relationship between depression and safety practices. Depression has been associated with pesticide poisoning and was more strongly associated with safety behaviors than workload, social support or health status of farm residents in a previously published report.

Methods: A cross-sectional survey of farmers and their spouses was conducted in eight counties in northeastern Colorado. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression (CES-D) scale. Exploratory and confirmatory factor analyses were used to identify symptoms most correlated with risk factors for depression and safety practices. SEM was used to examine theoretical causal models of the relationship between depression and poor health, financial difficulties, a history of pesticide poisoning, and safety practices.

Results: Exploratory factor analysis identified three factors in the CES-D scale. The SEM showed that poor health, financial difficulties and a history of pesticide poisoning significantly explained the depressive symptoms. Models with an excellent fit for the safety behaviors resulted when modeling the probability that the pesticide poisoning preceded depression, but no fit was possible when reversing the direction and modeling depression preceding pesticide poisoning.

Conclusions: Specific depressive symptoms appeared to be significantly associated with pri marily animal handling and farm machinery. The order of events, based on SEM results, was a pesti cide poisoning preceding depressed mood in relation to safety behaviors.     

Pesticide illness, farm practices, and neurological symptoms among farm residents in Colorado

The purpose of this study is to evaluate the association between pesticides and neurological symptoms among a population exposed to organophosphate chemicals as a result of agricultural use. Chronic sequelae of acute pesticide poisoning from organophosphate compounds include a variety of neurological symptoms including restlessness, irritability, and trouble sleeping. Individuals who have had an acute pesticide poisoning have been reported to suffer a wide range of neurological symptoms that occur from weeks to months after the initial episode. Data for this study came from a cross-sectional survey of farmers and their spouses conducted in an eight-county area in north-eastern Colorado. Neurological characteristics were assessed to determine their relationship with previously reported pesticide-related illnesses. Symptoms that were significantly associated with a previous poisoning were difficulty concentrating [OR 2.07, 95% confidence interval (CI) 1.22, 3.50]; relatives noticing person had trouble remembering things (OR 2.54, 95% CI 1.47, 4.39); making notes to remember things (OR 2.18, 95% CI 1.20, 3.97); finding it hard to understand the meaning of newspapers, magazines, and books (OR 1.90, 95% CI 1.01, 3.60); felt irritable (OR 1.84, 95% CI 1.08, 3.12); felt depressed (OR 2.82, 95% CI 1.65, 4.81); had heart palpitations without exertion (OR 2.83, 95% CI 1.22, 6.54); sleeping more than usual (OR 3.58, 95% CI 1.95, 6.58); difficulty moving fingers or grasping things (OR 2.08, 95% CI 1.06, 3.24); and headaches at least once a week (OR 1.85, 95% CI 1.06, 3.24). Stepwise regression was used to identify the best explanatory model of pesticide-related illness. Variables that were associated with increased odds of illness were being male, being depressed, sleeping too much, and using crop organophosphates.     

Pesticide poisoning and its related factors among Korean farmers

This study has been carried out to assess the health damages due to pesticide use and its related risk factors among Korean farmers. Data regarding pesticide handling and poisoning symptoms were collected by means of a questionnaire filled in by 1,032 farmers from two provinces. The results showed that during summer farming 21.9% of the subjects experienced suspected pesticide poisoning. 18.8% mild poisoning, and 2% more serious poisoning. Univariate and logistic regression analyses between "no poisoning", including the "suspected poisoning" and "poisoning" groups, were performed to select significant variables related to pesticide poisoning. Four variables were significantly associated: sex, days of consecutive pesticide use, hours of pesticide use per day, having received safety education (weakly associated), and compliance with safety guidelines for application. Safety education was weakly associated with poisoning, while age, education, wearing protective gear, and compliance with safety guidelines for personal hygiene after pesticide use were not significant risk factors to determine pesticide poisoning.     

Effect of pesticide exposure on acetylcholinesterase activity in subsistence farmers from Campeche, Mexico

The authors surveyed agricultural production methods and pesticide use among subsistence farmers (campesinos) in 4 rural communities of Campeche, Mexico. Self-reports of symptoms of poisoning resulting from occupational pesticide exposure were elicited by questionnaire (N = 121), and acetylcholinesterase (AChE) activity during insecticide use was evaluated from blood samples (N = 127). In individuals from 2 of the 4 communities, AChE activity was significantly lower (p < 0.05) than the mean of activity determined for individuals in a reference group. Results of this study show that erythrocyte AChE inhibition provides a good biomarker of exposure to organophosphate pesticides in field studies with human populations. Carbamates, particularly carbofuran, seem to be more associated with exuberant and diversified symptomatology of pesticide exposure than organophosphates. Studies in field communities where both carbamates and organophosphates are suspected to exist should include blood AChE determinations, symptomatology surveys, and socioeconomic questionnaires. The authors recommend that the Mexican National Health Ministry authorities specify additional provisions regarding the use of protective equipment and the adoption of other safety practices during field work, increase information campaigns about the risks of pesticide use and the value of safety practices, and increase programs of medical monitoring and assistance for rural communities dealing with pesticides.     

Effect of Pesticide Exposure on Acetylcholinesterase Activity in Subsistence Farmers from Campeche,Mexico

The authors surveyed agricultural production methods and pesticide use among subsistence farmers (campesinos) in 4 rural communities of Campeche, Mexico. Self-reports of symptoms of poisoning resulting from occupational pesticide exposure were elicited by questionnaire (N = 121), and acetylcholinesterase (AChE) activity during insecticide use was evaluated from blood samples (N = 127). In individuals from 2 of the 4 communities, AChE activity was significantly lower (p < 0.05) than the mean of activity determined for individuals in a reference group. Results of this study show that erythrocyte AChE inhibition provides a good biomarker of exposure to organophosphate pesticides in field studies with human populations. Carbamates, particularly carbofuran, seem to be more associated with exuberant and diversified symptomatology of pesticide exposure than organophosphates. Studies in field communities where both carbamates and organophosphates are suspected to exist should include blood AChE determinations, symptomatology surveys, and socioeconomic questionnaires. The authors recommend that the Mexican National Health Ministry authorities specify additional provisions regarding the use of protective equipment and the adoption of other safety practices during field work, increase information campaigns about the risks of pesticide use and the value of safety practices, and increase programs of medical monitoring and assistance for rural communities dealing with pesticides.     

Neurologic symptoms in licensed private pesticide applicators in the agricultural health study

Exposure to high levels of many pesticides has both acute and long-term neurologic consequences, but little is known about the neurotoxicity of chronic exposure to moderate levels of pesticides. We analyzed cross-sectional data from 18,782 white male licensed private pesticide applicators enrolled in the Agricultural Health Study in 1993-1997. Applicators provided information on lifetime pesticide use and 23 neurologic symptoms typically associated with pesticide intoxication. An indicator of more symptoms (> or = 10 vs. < 10) during the year before enrollment was associated with cumulative lifetime days of insecticide use: odds ratios (95% confidence intervals) were 1.64 (1.36-1.97) for 1-50 days, 1.89 (1.58-2.25) for 51-500 days, and 2.50 (2.00-3.13) for > 500 days, compared with never users. A modest association for fumigants [> 50 days, 1.50 (1.24-1.81)] and weaker relationships for herbicides [> 500 days, 1.32 (0.99-1.75)] and fungicides [> 50 days, 1.23 (1.00-1.50)] were observed. Pesticide use within the year before enrollment was not associated with symptom count. Only associations with insecticides and fumigants persisted when all four pesticide groups were examined simultaneously. Among chemical classes of insecticides, associations were strongest for organophosphates and organochlorines. Associations with cumulative exposure persisted after excluding individuals who had a history of pesticide poisoning or had experienced an event involving high personal pesticide exposure. These results suggest that self-reported neurologic symptoms are associated with cumulative exposure to moderate levels of fumigants and organophosphate and organochlorine insecticides, regardless of recent exposure or history of poisoning.     

Exposure to organophosphate (OP) pesticides and health conditions in agricultural and non-agricultural workers from Maule,Chile

The objective was to evaluate the characteristics of exposure to OP pesticides and health status in Chilean farm workers from the Maule Region. An occupational health questionnaire was administered in 207 agricultural and non-agricultural workers. For the group of agricultural workers, we asked about specific occupational exposure history and symptoms of OP pesticide poisoning. The main health problem of the exposed group was previous OP pesticide poisoning (p < 0.001). Fifty-six percent of agricultural workers reported symptoms consistent with acute OP pesticide poisoning. The use of respiratory personal protective equipment and younger age were protective against these symptoms, and number of years of OP pesticide exposure was positively associated with reporting symptoms of poisoning. Of the pesticide applicators 47 % reported using chlorpyrifos. The regulations regarding use and application of pesticides should be strengthened, as should training and intervention with workers to improve the use of personal protective equipment.     

Peripheral nervous system function and organophosphate pesticide use among licensed pesticide applicators in the Agricultural Health Study

Background: Evidence is limited that long-term human exposure to organophosphate (OP) pesticides, without poisoning, is associated with adverse peripheral nervous system (PNS) function.Objective: We investigated associations between OP pesticide use and PNS function by administering PNS tests to 701 male pesticide applicators in the Agricultural Health Study (AHS).Methods: Participants completed a neurological physical examination (NPx) and electrophysiological tests as well as tests of hand strength, sway speed, and vibrotactile threshold. Self-reported information on lifetime use of 16 OP pesticides was obtained from AHS interviews and a study questionnaire. Associations between pesticide use and measures of PNS function were estimated with linear and logistic regression controlling for age and outcome-specific covariates.Results: Significantly increased odds ratios (ORs) were observed for associations between ever use of 10 of the 16 OP pesticides and one or more of six NPx outcomes. Most notably, abnormal toe proprioception was significantly associated with ever use of 6 OP pesticides, with ORs ranging from 2.03 to 3.06; monotonic increases in strength of association with increasing use was observed for 3 of the 6 pesticides. Mostly null associations were observed between OP pesticide use and electrophysiological tests, hand strength, sway speed, and vibrotactile threshold.Conclusions: This study provides some evidence that long-term exposure to OP pesticides is associated with signs of impaired PNS function among pesticide applicators.     

Pesticides and respiratory symptoms among farmers

OBJECTIVE: Despite the intensive use of pesticides in agriculture there are few studies assessing the risk of respiratory conditions from this exposure. The study aimed at quantifying the prevalence of respiratory symptoms among farmers and evaluating its relationship with occupational use of pesticides and the prevalence of respiratory symptoms. METHODS: A cross-sectional study was conducted among 1,379 farmers from two municipalities of Southern Brazil in 1996. Frequency and type of chemical exposure and pesticide poisoning were recorded for both sexes. All subjects aged 15 years or older with at least 15 weekly hours of agricultural activity were interviewed. An adapted questionnaire developed by the American Thoracic Society was used for the assessment of respiratory symptoms. Multivariate logistic regression analysis was carried out. RESULTS: More than half (55%) of interviewees were male. The prevalence of asthma symptoms was 12% and chronic respiratory disease symptoms was 22%. Higher odds ratios for both asthma (OR=1.51; 95% CI: 1.07-2.14) and chronic respiratory disease (OR=1.34; 95% CI 1.00-1.81) symptoms were found in women. Logistic regression analysis identified associations between many forms of exposure to pesticides and increased respiratory symptoms. Occurrence of pesticide poisoning was associated with higher prevalence of asthma symptoms (OR=1.54; 95% CI: 1.04-2.58) and chronic respiratory disease symptoms (OR=1.57; 95% CI: 1.08-2.28). CONCLUSIONS: In spite of causality limitations, the study results provide evidence that farming exposure to pesticides is associated with higher prevalence of respiratory symptoms, especially when the exposure is above two days per month.     

Rural work and risk factors associated with pesticide use in Minas Gerais,Brazil

This paper aimed to characterize the rural work process in nine counties in Minas Gerais State, considering socio-demographic indicators, the land tenure structure of farm operations, and work practices related to pesticide use and poisoning Data were obtained through the Jorge Duprat Figueiredo Foundation for Workers' Safety and Occupational Medicine, which applied a questionnaire to 1,064 rural workers from 1991 to 2000. Through a logistic regression, risk factors associated with pesticide poisoning were obtained for the carbamate and organophosphate groups. Some 50% of interviewees displayed at least moderate pesticide toxicity. Risk factors for pesticide poisoning were: last contact with pesticides less than two weeks before the blood cholinesterase test; no use of personal protective equipment by workers applying pesticides; having received instructions from the pesticide salesperson; report of carbamates/organophosphates as the main pesticides used; and working in the counties of Te foli Otoni, Guidoval, or Piraúba. The results emphasize the high level of health risk associated with pesticide use among these rural workers.     

Acute Pesticide Poisoning among Female and Male Cotton Growers in India

Abstract

A season-long assessment of acute pesticide poisoning among farmers was conducted in three villages in India. Fifty female cotton growers reported the adverse effects experienced after exposures to pesticides by themselves and by their male relatives (n = 47). The study documented the serious consequences of pesticide use for the health of farmers, particularly women field helpers. Typically female tasks such as mixing on centrated chemicals and refilling spraying tanks were as hazardous as direct pesticide application. Of 323 reported events, 83.6% were associated with signs and symptoms of mild to severe poisoning, and 10% of the pesticide application sessions were associated with three or more neurotoxic/systemic signs and symptoms typical of poisoning by organophosphates, which were used in 47% of the applications. Although in 6% of the spray sessions the workers' neurotoxic effects were extremely serious, none sought medical care. Low-income marginal farmers were, more often subjected to severe poisoning than were landlords.     

Ambient temperature and pesticide poisoning: a time-series analysis

ABSTRACT

Limited studies have explored the association between ambient temperature and the disease burden of pesticide poisoning. Our study aims to estimate associations between daily mean temperature and pesticide poisoning incidence with lag effect. A distributed lag nonlinear model with Poisson distribution was used to examine the nonlinear lagged effects of ambient temperature on pesticide poisoning incidence. Overall, the estimated effects of temperature on pesticide poisoning incidence were non-linear, with higher relative risks (RRs) at hotter temperatures. It was found that the high temperature had acute and short-term effects and then declined rapidly along the lag days with the maximum risk occurring 0 day of exposure. Considering the 5-day cumulative RR for daily mean temperature, the temperature generally showed a positive association with the pesticide poisoning incidence, achieving the maximum risk at 31°C. In general, pesticide poisoning incidence increased with higher temperatures, with the strongest effects occurring shortly.     

Acute pesticide poisoning among female and male cotton growers in India

A season-long assessment of acute pesticide poisoning among farmers was conducted in three villages in India. Fifty female cotton growers reported the adverse effects experienced after exposures to pesticides by themselves and by their male relatives (n=47). The study documented the serious consequences of pesticide use for the health of farmers, particularly women field helpers. Typically female tasks such as mixing concentrated chemicals and refilling spraying tanks were as hazardous as direct pesticide application. Of 323 reported events, 83.6% were associated with signs and symptoms of mild to severe poisoning, and 10% of the pesticide application sessions were associated with three or more neurotoxic/systemic signs and symptoms typical of poisoning by organophosphates, which were used in 47% of the applications. Although in 6% of the spray sessions the workers' neurotoxic effects were extremely serious, none sought medical care. Low-income marginal farmers were more often subjected to severe poisoning than were landlords.     

High pesticide exposure events and central nervous system function among pesticide applicators in the Agricultural Health Study

Purpose

While acute pesticide poisoning can be associated with persistent adverse central nervous system (CNS) effects, little is known about the effect of one or more episodic and unusually high pesticide exposure events (HPEE) that typically do not result in acute poisoning. The objective of this investigation was to examine the association between ever having an HPEE and CNS function among licensed pesticide applicators enrolled in the Agricultural Health Study (AHS).

Methods

In 2006–2008, 693 male participants with no history of a physician-diagnosed pesticide poisoning completed nine neurobehavioral tests to assess memory, motor speed, sustained attention, verbal learning, and visual scanning and processing. Information on ever having an HPEE and pesticide poisonings was obtained from previous AHS interviews. Associations between ever having an HPEE and neurobehavioral outcomes were estimated with linear regression controlling for age and outcome-specific covariates.

Results

A history of ever having an HPEE was reported by 156 (23%) participants. Adverse associations were observed between ever having an HPEE and two of the nine neurobehavioral tests. On a test of visual scanning and processing (Digit-Symbol), participants who ever had an HPEE were 4.2?s slower (95% CI: ?7.27, ?1.11) than those without an HPEE, equivalent to the effect of 3.9?years of age in this population. On a test of visual scanning and motor speed (Sequences A), participants who ever had an HPEE were 2.5?s slower (95% CI: ?4.53, ?0.41) than those without an HPEE, equivalent to the effect of 3.9?years of age. No significant associations were observed between participants who ever had an HPEE and the remaining neurobehavioral tests.

Conclusions

One or more HPEE may contribute to adverse CNS outcomes independent of diagnosed pesticide poisoning.     

Pesticides exposure in Culturama, Brazil--knowledge, attitudes, and practices

In this study, the knowledge, attitudes, and practices associated with pesticide use and exposure were evaluated in the agricultural community of Culturama, in the state of Mato Grosso do Sul, Brazil. A standardized questionnaire was completed by 250 farm workers aged > or =18 years old. The average age of the studied population was 43.6 years and 17.6% had never been to school. Their farms were small (approximately 30ha) and family operated and did not utilize advanced farming technology. About 92% of the interviewees had worked directly with pesticides and 59.6% reported typical intoxication symptoms. Only 44.3%, however, believe that they had been intoxicated. A significant correlation was found between hand washing after pesticide application and reporting symptoms (P=0.014). Over 90% of the farmers reported using the organophosphorus insecticide methamidophos. A great majority (>90%) considered pesticides to be harmful to human health, but less than 20% used masks, impermeable clothes, or gloves during pesticide application. These results indicate that special educational programs, legislation promoting the use of safer pesticides, and implementation of personal protective measures are necessary to decrease the pesticide exposure of farmers in Culturama.     

Knowledge, attitude and practices of pesticide use and acetylcholinesterase depression among farm workers in Nepal

Assessing erythrocyte acetylcholinesterase (AChE) activity in farm workers across agricultural seasons can be used to monitor risks of pesticide exposure. We surveyed a total of 403 households in Nepal and adopted the Test-mate ChE Cholinesterase Test System to monitor AChE activity across season on the 127 individuals of the sampled households. The study aims to (i) document knowledge and practices of pesticide use among farmers and (ii) present the relationship between farmers' reported acute health symptoms and erythrocyte acetylcholinesterase depression. We found low levels of pesticide use hygiene and high levels of individuals' knowledge on the local environmental impacts of pesticide use. Safety measures taken against potential risks of pesticides exposure were inadequate. Exposure to organophosphates significantly reduced AChE activity across season, but was not sufficient enough to claim clinical symptoms whereas exposure to the pyrethroid insecticides and fungicides were sufficient enough to claim acute symptoms of poisoning.     

Health symptoms and occupational exposure to flea control products among California pet handlers

A statewide telephone survey of health symptoms associated with occupational exposure to flea control products among California pet handlers was conducted in 1987 following several reports of ill workers. The 696 employees interviewed worked at veterinary clinics, pet stores, pet boarding kennels, pet grooming shops, and animal control facilities. Symptom incidence and frequency and flea control product use were reported for the 3 months prior to interview. Eye and skin symptoms and unusual tiredness were elevated among workers who applied flea control products to animals or facilities. After adjustment for potential confounders, these symptoms were elevated 64% to 258% among applicators as compared to nonapplicators who worked in the same facilities. Workers who used protective clothing and equipment and followed some protective work practices were not at increased symptom risk. Some specific flea control active ingredients and application procedures were associated with respiratory effects and with symptoms suggesting systemic pesticide poisoning.     

Knowledge and practices of pesticide use among farm workers in the West Bank,Palestine: safety implications

Objectives  

The objectives of this study were to assess the knowledge and practices associated with pesticide use in an agricultural community in Palestine, and to determine the prevalence of self-reported health symptoms related to pesticide exposure.     

Taiwanese farm workers’ pesticide knowledge,attitudes, behaviors and clothing practices

The purpose of this study was to assess Taiwanese fruit farm workers’ knowledge, attitudes, behaviours, and clothing practices regarding pesticide activities. Seventy-seven fruit farm workers from four districts of Tainan City, Taiwan completed the questionnaire. Results indicated that farmer workers had a good overall level of knowledge of the adverse effects of pesticides on human health and most had experienced symptoms of pesticide poisoning. Farm workers’ attitudes toward pesticide use and handling indicated that they saw pesticides useful in controlling pests. Farm workers indicated the limited availability of comfortable clothing designed for a hot and humid climate while still providing sufficient protection was the main reason for not wearing personal protective clothing (PPC) and personal protective equipment (PPE). Emphasis on safety precautions is needed when using pesticides, and the importance of PPC and PPE is essential for the health of farm workers.