Neurobehavioral Performance of Adult and Adolescent Agricultural Workers

Center for Research on Occupational and Environmental Toxicology (CROET), L606, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
NeuroToxicology (Impact Factor: 3.38). 04/2007; 28(2):374-80. DOI: 10.1016/j.neuro.2006.10.006
Source: PubMed


There are many occupational hazards associated with working in agriculture including risk of injury and exposure to pesticides. Research examining neurobehavioral effects of pesticide exposure have focused primarily on the acute effects in adults working in agriculture. Organophosphate poisoned populations have shown a consistent pattern of deficits when compared to a non-exposed or non-poisoned population on measures of motor speed and coordination, sustained attention, and information processing speed. Fewer studies have examined the effect of long-term low-level exposure on nervous system functioning in agricultural workers. Pesticides are thought to pose a considerably higher risk to children than to adults, yet little is known about the extent or magnitude of health problems related to occupational exposure to pesticides in children and adolescents. The present study compared the neurobehavioral performance of adolescents and adults working in agriculture and examined the impact of years working in agriculture on neurobehavioral performance. One hundred seventy-five Hispanic adolescent and adults completed a neurobehavioral test battery consisting of 10 computer-based tests measuring attention, response speed, coordination and memory. Age, gender, school experience, and years working in agriculture all impacted performance on the neurobehavioral tests. Comparison of adult and adolescents did not reveal decreased neurobehavioral performance in adolescents. On several tests the adolescents performed better than adult counterparts. The adolescents and adults were engaged in comparable agricultural working environments at the time of the neurobehavioral testing. These findings suggest that, at the time of exposure to pesticides, adolescents are not more vulnerable to the effects of working in agriculture. Evidence from this study suggests that cumulative exposure to low levels of pesticides over many years of agricultural work is associated with neurological impairment as measured by the Selective Attention, Symbol-Digit, Reaction Time tests. Experience handling pesticides was also associated with deficits in neurobehavioral performance.

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Available from: Diane Rohlman
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    • "Behavioral studies of pesticide applicators, greenhouse workers , agricultural workers and farm residents exposed repeatedly over months or years to low levels of OPs reveal a relatively consistent pattern of neurobehavioral deficits. Although several studies have examined children who live in agricultural communities or whose parents work in agriculture, only a few studies have examined adolescents who are currently working in agriculture (Eckerman et al., 2007; Rohlman et al., 2007, 1999). The most extensive range of deficits were shown in a population of adolescents applying pesticide in Egypt (Abdel Rasoul et al., 2008). "
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    ABSTRACT: The association between pesticide exposure and neurobehavioral and neurodevelopmental effects is an area of increasing concern. This symposium brought together participants to explore the neurotoxic effects of pesticides across the lifespan. Endpoints examined included neurobehavioral, affective and neurodevelopmental outcomes among occupational (both adolescent and adult workers) and non-occupational populations (children). The symposium discussion highlighted many challenges for researchers concerned with the prevention of neurotoxic illness due to pesticides and generated a number of directions for further research and policy interventions for the protection of human health, highlighting the importance of examining potential long-term effects across the lifespan arising from early adolescent, childhood or prenatal exposure.
    Full-text · Article · Jan 2012 · NeuroToxicology
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    • "For the third, most participants had worked in agriculture since childhood, with several decades of pesticide exposure. Cumulative years as well as recent experience working with pesticides are both thought to contribute to neurobehavioral deficits [31]. Unlike long duration cohort studies showing Parkinson's Disease and Alzheimer's disease impacts of such exposure in the elderly [32], shorter duration cohort studies of neurobehavioral performance are rare. "
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    ABSTRACT: Longitudinal studies using multi-level models to examine health inequalities in lower and middle income countries (LMICs) are rare. We explored socio-economic gradients in health among small farm members participating in a pesticide-related health and agriculture program in highland Ecuador. We profiled 24 communities through key informant interviews, secondary data (percent of population with unsatisfied basic needs), and intervention implementation indicators. Pre (2005) and post (2007) surveys of the primary household and crop managers included common questions (education, age, and the health outcome - digit span scaled 0-10)) and pesticide-related practice questions specific to each. Household assets and pesticide use variables were shared across managers. We constructed multi-level models predicting 2007 digit span for each manager type, with staged introduction of predictor variables. 376 household managers (79% of 2005 participants) and 380 crop managers (76% of 2005 participants) had complete data for analysis. The most important predictor of 2007 digit span was 2005 digit span: β (Standard Error) of 0.31(0.05) per unit for household and 0.17(0.04) for crop managers. Household asset score was next most important: 0.14(0.06) per unit for household and 0.14(0.05) for crop managers. Community percent with unsatisfied basic needs was associated with reductions in 2007 digit span: -0.04(0.01) per percent for household and -0.03(0.01) for crop managers. The important roles of life endowments and/or persistent neurotoxicity were exemplified by limited change in the health outcome. Gradients by household assets and community deprivation were indicative of ongoing, structural inequities within this LMIC.
    Full-text · Article · Nov 2011 · International Journal for Equity in Health
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    • "However, evidence for an association between long-term low or moderate exposure to OPs and impaired neurobehavioral (NB) function or other neurological effects is inconsistent [5] [8] [12] [13] [21] [22] [23] [25]. The heterogeneity of findings reported in the literature may be due to a number of methodological limitations including small sample size [5] [9] [28], use of poor or inaccurate exposure estimates [8] [13] [18] [22] [23], referent groups that may have differed from the exposure group on characteristics other than exposure (e.g., sheep dippers versus ceramic workers) [5] [8] [9] [21] [28], and inadequate control for potential confounding variables, such as previous pesticide poisoning [3] [5] [8] [21]. "
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    ABSTRACT: Although persistent decrements in cognitive function have been observed among persons who have recovered from clinically overt organophosphate (OP) pesticide poisoning, little is known about the cognitive effects of chronic OP exposures that do not result in acute poisoning. To examine associations between long-term pesticide use and neurobehavioral (NB) function, NB tests were administered to licensed pesticide applicators enrolled in the Agricultural Health Study (AHS) in Iowa and North Carolina. Between 2006 and 2008, 701 male participants completed nine NB tests to assess memory, motor speed and coordination, sustained attention, verbal learning and visual scanning and processing. Data on ever-use and lifetime days of use of 16 OP pesticides were obtained from AHS interviews conducted before testing between 1993 and 2007 and during the NB visit. The mean age of participants was 61 years (SD=12). Associations between pesticide use and NB test performance were estimated with linear regression controlling for age and outcome-specific covariates. NB test performance was associated with lifetime days of use of some pesticides. Ethoprop was significantly associated with reduced performance on a test of motor speed and visual scanning. Malathion was significantly associated with poor performance on a test of visual scanning and processing. Conversely, we observed significantly better test performance for five OP pesticides. Specifically, chlorpyrifos, coumaphos, parathion, phorate, and tetrachlorvinphos were associated with better verbal learning and memory; coumaphos was associated with better performance on a test of motor speed and visual scanning; and parathion was associated with better performance on a test of sustained attention. Several associations varied by state. Overall, we found no consistent evidence of an association between OP pesticide use and adverse NB test performance among this older sample of pesticide applicators. Potential reasons for these mostly null results include a true absence of effect as well as possible selective participation by healthier applicators.
    Full-text · Article · Aug 2011 · Neurotoxicology and Teratology
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