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Cognitive deficits in organophosphate exposed children of Nicaraguan subsistence farmers
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences. (Occupational and Environmental Medicine)
Central American Institute for Studies on Toxic Substances (IRET), Universidad Nacional, Heredia, Costa Rica.
National Institute of Public Health (INSP), Cuernavaca, Morelos, Mexico.
Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, Sweden.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Objective: This study examined cognitive and behavioral performance among school-age children in Nicaragua in relation with long-term and recent organophosphate exposures.

Methods: Long-term organophosphate was assessed in 110 children aged 7-9 through a parental use index of kg of organophosphate during de pregnancy, first year of life and from 1 year old to the present. Recent exposure was determined in a subset of 74 children by urinary 3,5,6-trichloro-2-pyridinol (TCPY) levels. Cognitive function was evaluated with Wechsler Intelligence Scale for Children (WISC IV), total IQ and subtests grouped into indices for perceptual reasoning, verbal comprehension, working memory, and processing speed. Behavior at school was measured with the Conners’ Teacher Rating Scale-Revised:Short (CTRS-R:S). Multivariate linear regression models assessed adjusted associations.

Results: For each 10-fold increase in prenatal indices for total OP use, children’s performance on working memory significantly decreased with 3.5 points, and similarly for chlorpyrifos and methamidophos. Prenatal methamidophos use was, in addition, significantly associated with poorer verbal comprehension and decrease in total IQ, a 10-fold use increase decreasing scores with 3.8 and 3.3 points respectively. Urinary TCPY (mg/g of creatinine) also affected, not significantly, working memory with a 3.2 point decrease for each 10-fold increase. This study did not find associations between postnatal organophosphate use indices and cognitive performance, or pre or postnatal use indices with behavior.

Conclusion: Prenatal exposure to organophosphates decreased the cognitive abilities in Nicaraguan children, particularly in working memory. Methamidophos was also associated with poor verbal comprehension and total IQ.

Keyword [en]
organophosphates, children, pesticide, cognitive function, behavior, neurodevelopment
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine; Epidemiology
URN: urn:nbn:se:uu:diva-182148OAI: oai:DiVA.org:uu-182148DiVA: diva2:558603
Available from: 2012-10-04 Created: 2012-10-04 Last updated: 2012-10-29
In thesis
1. Environmental Pesticide Exposure and Neurobehavioral Effects among Children of Nicaraguan Agricultural Workers
Open this publication in new window or tab >>Environmental Pesticide Exposure and Neurobehavioral Effects among Children of Nicaraguan Agricultural Workers
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Children exposed to pesticides are susceptible for neurodevelopmental disruption. Data from developing countries are scarce.

Aim: Assessing long-term and recent pesticide exposure in Nicaraguan children in relation to parental pesticide use and examining potential associated neurobehavioral effects.

Methods: In the first study, pre- and post-spraying urinary residues of the chlorpyrifos metabolite TCPY and diazinon metabolite IMPY were measured among 7 subsistence farmers and 10 plantation workers, and in one child per worker. In the second study, for 110 children in an agricultural village and 22 in a non-agricultural village, aged 7-9, parental pesticide use was assessed by hours of spraying and kilograms of active ingredients during pre-and-postnatal time windows, as proxies for children’s long term pesticide exposures. Urinary TCPY, 3-PBA (pyrethroid metabolite), and 2,4-D were determined in 211 samples of 74 children of the agricultural village. IQ components and total IQ (WISC-IV) were evaluated in all agricultural village children. Behavior was evaluated with the Conners’ Teacher Rating Scale-Revised: Short. Multivariate linear regression models assessed associations between long-term and recent exposure to organophosphates and pyrethroids and cognitive and behavioral scales.

Results: In study 1, post-spraying urinary levels of pesticide metabolites of subsistence farmers and their children were highly correlated (r=0.85), but not those of plantation workers and their children. In study 2, a wide range of exposures was reported by parents for all pesticides and time windows. The median urinary TCPY (3.7 μg/g creatinine), 3-PBA (2.8), and 2,4-D (0.9) were comparable to other studies for TCPY and 3-PBA but high for 2,4-D. Maximum levels were the highest reported for all compounds. Prenatal use of organophosphates affected working memory, and methamidophos also verbal comprehension and total IQ. Urinary TCPY was associated with poorer working memory. Organophosphate exposures were not associated with children’s behavior. Pyrethroid exposure during the first year of life associated with poorer perceptual reasoning and behavior, and urinary 3-PBA with a number of cognitive functions and ADHD in girls but not in boys.

Conclusion: Nicaraguan children in poor agricultural areas are highly exposed to pesticides, which is influenced by parental pesticide use in subsistence farms. Organophosphate and pyrethroid exposures adversely affect their neurobehavioral development.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 66 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 820
pesticides, organophosphates, pyrethroids, children, cognitive function, behavioral outcomes, neurodevelopment
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine; Epidemiology
urn:nbn:se:uu:diva-182164 (URN)978-91-554-8488-0 (ISBN)
Public defence
2012-11-15, Frödingsalen, Ulleråkersvägen 40 A, Uppsala, 09:00 (English)
Available from: 2012-10-24 Created: 2012-10-04 Last updated: 2013-01-23

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