Residential Proximity to Agricultural Pesticides Affects Neurodevelopment in Children

by | Aug 2, 2018 | 2017, Environmental Health, Infant and Children's Health, Pesticides and Solvents

Written by Angeline A. De Leon, Staff Writer. This study demonstrates an inverse relationship between prenatal residential proximity to agricultural use of potentially neurotoxic pesticides and poorer neuro-development in 7-year-old children.

In recent years, widespread exposure to organophosphate (OP) pesticides has been reported in the general U.S., with higher exposure rates documented in agricultural populations 1,2. Populations in agricultural areas receive a mixture of neurotoxic pesticide exposure, through pesticide drift and occupational exposure 3, making them particularly vulnerable to certain adverse health outcomes. The effects of pesticide exposure are well-documented in pregnant women and children, with higher nearby agricultural OP use showing a correlation with neural tube defects 4, birth defects 5, and autism 6. For example, in an epidemiological study in California involving pregnant women living or working in an agricultural region and/or living with people in the industry, an adverse association was found between prenatal maternal concentrations of dialkylphosphate (DAP) (biomarkers of OP) and measures of attention and cognitive performance in their children 7,8. Findings on the potential effects of other neurotoxic pesticides, besides OP, on cognitive development of children have been more limited, however. Therefore, researchers at the University of California at Berkeley (2017) sought to evaluate the association between prenatal residential proximity to a variety of agricultural pesticides and neurodevelopment in 7-year-old children.

In the agricultural Salinas Valley of California, a total of 283 pregnant women (aged 18 years and older) and their children were tracked as part of a longitudinal cohort study. Using a geographic information system, residential location, and comprehensive agricultural Pesticide Use Report data in California, agricultural pesticide use was estimated within 1 km of maternal residence during each trimester of pregnancy, with prenatal urinary DAP concentrations used as an estimate of exposure to OP pesticides. Neurotoxic pesticide use included five pesticide classes of interest (OPs, carbamates, pyrethroids, neonicotinoids, and manganese fungicides) and five individual OPs (acephate, chlorpyrifos, diazinon, malathion, and oxydemeton-methyl). At seven years of age, children were administered the Wechsler Intelligence Scale for Children, fourth edition (WISC-IV) to assess cognitive ability.

Findings showed that IQ scores generally diminished across all cognitive domains with increasing use of OP pesticides within 1 km of maternal residence during pregnancy: each standard deviation increase in toxicity-weighted OP use during pregnancy was accompanied by an estimated 2.2-point reduction in Full-Scale IQ (95% Confidence Interval: -3.9 to –0.5) and a 2.9-point reduction in Verbal Comprehension (95% CI: -4.4 to –1.3). Similarly, a significant reduction in Full-Scale IQ was observed with each standard deviation increase in use of two OPs (acephate β = -2.3, 95% CI: -3.9 to –0.6; oxydemeton-methyl β = -2.3, 95% CI: -4.0 to –0.7) and three neurotoxic pesticide groups (pyrethroids β = -2, 95% CI: -3.7 to –0.3; neonicotinoids = -1.7, 95% CI: -3.3 to 0.0; manganese fungicides = -2, 95% CI: -3.7 to –0.2).

Overall, results confirm an inverse relationship between cognitive development in children and agricultural use of OPs and other neurotoxic pesticides within 1 km of maternal residence during pregnancy. This study represents initial evidence for the negative impact of proximal maternal residential pesticide exposure on neurodevelopment in children. Replication of findings in women and children living in non-agricultural communities would further help in characterizing the variable effects of pesticides in relation to child development.

Source: Gunier RB, Bradman A, Harley KG, et al. Prenatal residential proximity to agricultural pesticide use and IQ in 7-year-old children. Environ Health Perspect. 2017; 125(5): 057002. DOI: 10.1289/EHP504.

Environmental Health Perspectives is a peer-reviewed open access journal published by the National Institute of Environmental Health Sciences.

Click here to read the full text study.

Posted August 2, 2018.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

References:

  1. Whyatt RM, Barr DB, Camann DE. Contemporary-Use Pesticides in Personal Air Samples during Pregnancy and Blood Samples at Delivery among Urban Minority Mothers and Newborns. Environ Health Perspect. 2003; 111(5): 749–756.
  2. Lu C, Kedan G, Fisker-Andersen J, et al. Multipathway organophosphorus pesticide exposures of preschool children living in agricultural and nonagricultural communities. Environ Res. 2004; 96(3): 283–289.
  3. Fenske RA, Lu C, Barr D, et al. Children’s exposure to chlorpyrifos and parathion in an agricultural community in central Washington State. Environ Health Perspect. 2002; 110(5): 549–553.
  4. Rull RP, Ritz B, Shaw GM. Neural tube defects and maternal residential proximity to agricultural pesticide applications. Am J Epidemiol. 2006; 163(8): 743–753.
  5. Carmichael SL, Yang W, Roberts E, et al. Residential agricultural pesticide exposures and risk of selected congenital heart defects among offspring in the San Joaquin Valley of California. Environ Res. 2014; 135C: 133–138.
  6. Shelton JF, Geraghty EM, Tancredi DJ, et al. Neurodevelopmental disorders and prenatal residential proximity to agricultural pesticides: The CHARGE Study. Environ Health Perspect. 2014; 122(10): 1103–1109.
  7. Marks AR, Harley K, Bradman A, et al. Organophosphate pesticide exposure and attention in young Mexican-American children: The CHAMACOS study. Environ Health Perspect. 2010; 118(12): 1768–1774.
  8. Bouchard MF, Chevrier J, Harley KG, et al. Prenatal exposure to organophosphate pesticides and IQ in 7-year-old children. Environ Health Perspect. 20111; 119(8): 1189–1195.