Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R36-OH-009402, 2010 Aug; :1-35
INTRODUCTION: Children of agricultural workers are at risk of pesticide contamination through secondary routes (e.g. take-home pathway). Animal and human studies suggest that pesticide intoxication in early childhood delays growth and neurodevelopment. Objectives: The Effects of Secondary Pesticide Exposure on Infants, Children and Adolescents (ESPINA) study evaluated the effects of secondary pesticide exposure on childhood growth and neurobehavioral development among children living in a county with an active Fresh-cut flower industry. The following hypotheses were addressed: compared to children without secondary pesticide exposure (operationalized as flower worker (FW) cohabitation), exposed children will have 1) lower acetylcholinesterase (AChE) concentration, 2) lower neurobehavioral development scores, 3) slower growth, 4) higher systolic blood pressure, and 5) lower resting heart rate. METHODS: ESPINA included socio-economic, demographic and anthropometric (height and weight) information of children from 0 to 5 years of age who participated in 2004 in the Survey of Access and Demand of Health Services in the County of Pedro Moncayo (SAHS-PM 2004). Pedro Moncayo County, Pichincha, Ecuador, has one of the highest concentrations of flower plantations per capita worldwide. In 2008, ESPINA examined children 4 to 9y living in the County to obtain anthropometric measurements, a neurobehavioral developmental assessment and hemoglobin and AChE measurements. Most of the children examined in 2008 were also examined in the SAHS-PM-2004. Study Design: This study is composed of: 1) a cross-section of 2004 to assess growth, 2) a cross-section of 2008 to assess neurobehavioral development, head circumference, heart rate, blood pressure and blood AChE levels; and 3) a longitudinal component (2004-2008) to assess growth. RESULTS: a) Participant Characteristics: 922 (51% female) children were included from the SAHS-PM 2004; the mean age was 2.3 y (standard deviation (SD): 1.4), 63% cohabited with >1 FW with a mean of 2.0 FWs at home. In 2008, 313 (49% female, 78% mestizo) children participated; the mean age was 6.6y (SD=1.6), and 55% of participants cohabited with >1 FW. FW cohabitants had a mean duration of cohabitation of 5.3 years and a mean of 1.5 FWs at home. 230 (49% female, 74% mestizo) children were examined in 2004 and 2008; the mean age was 6.4 years (SD=1.4) and 59% cohabited with > 1 FWs. FW cohabitants had a mean duration of cohabitation of 5.1 years and a mean of 1.5 FWs at home in 2008. b) Flower worker cohabitation and AChE concentration: After adjustment for gender, age, height-for-age, hemoglobin concentration, parish of residence, income, pesticide use within household lot and pesticide use by contiguous neighbors, children cohabiting (vs. not) with a FW had a lower mean of AChE by 0.10 U-ml (p=0.049). Their adjusted odds ratio (OR) for low AChE (<2.4 U/ml) was 2.84 (95%CI: 1.09-7.39). Every year of cohabitation was associated with an adjusted AChE decrease of 0.02 U/ml (p=0.038). c) Secondary Pesticide Exposure and Neurobehavioral Development: Children's cohabitation with a FW was associated with a decrease of 1.17 units (p=0.020) in the Auditory Attention score (Attention and Executive Functioning (AEF) Domain) after adjustment for gender, age, race, hemoglobin concentration, height for age, maternal education, income and parish of residence. Every year of FW cohabitation was associated with an adjusted decrease of 0.15 units (p=0.055) of Auditory Attention. FW cohabitation was associated with an adjusted OR of 2.58 (95%CI 1.24-5.38) of having low Auditory Attention scores. Every unit decrease in AChE was associated with an adjusted decrease of 1.07 units (p=0.057) of Inhibition (AEF Domain). Participants with AChE concentrations in the lowest vs. the highest tertile and middle vs. highest tertile had adjusted ORs of 3.27 (95%CI 1.32-8.12) and 2.35 (95%CI 1.05-5.29) for low Inhibition scores, respectively. For low Memory for Faces Delayed scores (Memory and Learning (ML) Domain), AChE concentrations in the lowest vs. the highest tertile and middle vs. highest tertile were associated with adjusted ORs of 3.59 (95%CI 1.33-9.64) and 2.58 (95%CI 1.05-6.34), respectively. AChE concentrations in the lowest vs. the highest tertile had an adjusted OR of 4.05 (1.02-16.16) for low Word List Interference Repetition scores (ML Domain). d) Secondary Pesticide Exposure and Growth: In 2004 and 2008, FW cohabitation was not associated with height-for-age after adjusting for age, gender, race, parish of residence and socio-economic variables (2004: household head education, type of home, home roof materials, home floor materials, type of wastewater disposal; 2008: income and maternal education). The number of FWs cohabiting with the participant (2004 and 2008), AChE concentration and duration of cohabitation (2008) had no adjusted effect on height-for-age, weight-for-age or BMI-for-age. Also, FW cohabitation was not associated with change between 2004 and 2008 in these three measures. e) Secondary Pesticide Exposure and Blood Pressure and Resting Heart Rate. Concurrent FW cohabitation was associated with a systolic blood pressure (SBP) decrease of 2.08 mmHg (p=0.029) after adjustment for age, gender, height-for-age, resting heart rate, hemoglobin concentration, parish of residence, and income. Duration of cohabitation was inversely related to SBP, with an adjusted decrease of 0.34 mmHg (p=0.032) per year of cohabitation. AChE was directly associated with diastolic blood pressure (DBP). Every SD (0.49 U/ml) of AChE was associated with a change of 1.56 mmHg (p=0.002) in DBP. AChE was not associated with systolic blood pressure or pulse pressure but was associated with a mean blood pressure change of 1.26 mmHg (p=0.005) per SD. Resting heart rate was not associated with FW cohabitation or AChE concentrations. CONCLUSIONS: 1) Indirect pesticide exposure from FW cohabitation suffices to depress acetylcholinesterase concentration, with greater suppression due to longer exposure. 2) FW cohabitation was associated with lower Auditory Attention scores, with a significant decrease with increasing length of cohabitation. AChE was inversely related to Inhibition (Attention and Executive Functioning Domain), Memory for Faces Delayed (Memory and Learning), and Word List Interference Repetition (Memory and Learning). These findings are in line with previous research where children exposed to pesticides had lower scores on attention, inhibition of active behavior, short-term memory, learning and motor development. 3) We found no association between FW cohabitation and AChE with height-for-age, weight-for-age or BMI-for-age in this population. These growth measures were mainly affected by SES. 4) FW cohabitation and duration of cohabitation were associated with a decrease in SBP which remained present even after adjusting for AChE. This may suggest a role of secondary exposure to non-cholinesterase inhibiting pesticides on SBP and/or the presence of additional behavioral/SES confounders that were not accounted for. AChE has primarily an effect on DBP as evidenced by its direct association with DBP and mean blood pressure but not with SBP or pulse pressure, even after adjustment for resting heart rate. RECOMMENDATION: Take home pesticide exposures need to be addressed in greater extent by flower plantations and their workers to reduce the burden of these contaminants on their families.
José Ricardo Suárez, MD, MPH, PhD Candidate - Epidemiology Post-Doctoral Fellow Cardiovascular Disease, Division of Epidemiology and Community Health, University of Minnesota, 1300 S. 2nd Street, Suite 300, Minneapolis, MN 55454