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Environmental Pesticide Exposure and Neurobehavioral Effects among Children of Nicaraguan Agricultural Workers
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences. (Occupational and Environmental Medicine)
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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 820
Keyword [en]
pesticides, organophosphates, pyrethroids, children, cognitive function, behavioral outcomes, neurodevelopment
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine; Epidemiology
Identifiers
URN: urn:nbn:se:uu:diva-182164ISBN: 978-91-554-8488-0 (print)OAI: oai:DiVA.org:uu-182164DiVA: diva2:558620
Public defence
2012-11-15, Frödingsalen, Ulleråkersvägen 40 A, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2012-10-24 Created: 2012-10-04 Last updated: 2013-01-23
List of papers
1. Biological Monitoring of Pesticide Exposures among Applicators and Their Children in Nicaragua
Open this publication in new window or tab >>Biological Monitoring of Pesticide Exposures among Applicators and Their Children in Nicaragua
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2006 (English)In: International journal of occupational and environmental health, ISSN 1077-3525, E-ISSN 2049-3967, Vol. 12, 312-320 p.Article in journal (Refereed) Published
Abstract [en]

Exposures were assessed for seven small-scale farmers using chlorpyrifos on corn and ten banana plantation employees applying diazinon, and for one child of each worker. Metabolites (TCPYand IMPY) were measured in urine before and after applications. TCPY concentrations peaked at 27 and 8.5 hours post-application for applicators and children, respectively (geometric means, 26 and 3.0 microg/L). Proximity to spraying and spray mixture preparation in homes were important exposure factors. IMPY concentrations differed substantially across workers at two plantations (geometric means, 1.3 and 168 mirog/L); however, their children had little or no diazinon exposure. These workers and children were also exposed to chlorpyrifos, most likely through contact with chlorpyrifos-impregnated bags used in banana production. Several recommendations are offered: (1) monitor children's activities during applications; (2) do not store or prepare pesticides in homes; (3) institute sound occupational hygiene practices at banana plantations; (4) dispose of plastic insecticide bags properly at the worksite.

Place, publisher, year, edition, pages
Maney Publishing, 2006
Keyword
pesticide exposure; Nicaragua; chlorpyrifos; diazinon; urinary metabolite; biological monitoring; applicators; children
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine; Epidemiology
Identifiers
urn:nbn:se:uu:diva-182143 (URN)
Available from: 2012-10-04 Created: 2012-10-03 Last updated: 2017-12-07
2. Assessment of long-term and recent pesticide exposure among rural school children in Nicaragua
Open this publication in new window or tab >>Assessment of long-term and recent pesticide exposure among rural school children in Nicaragua
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2012 (English)In: Occupational and Environmental Medicine, ISSN 1351-0711, E-ISSN 1470-7926, Vol. 69, no 2, 119-125 p.Article in journal (Refereed) Published
Abstract [en]

Objective This study assessed pesticide exposure of children in rural Nicaragua in relation to parental pesticide use, from around conception to current school age, as part of an epidemiological evaluation of neurodevelopment effects. Methods We included 132 children whose parents were subsistence farmers or plantation workers, or had an agricultural history. As proxies for children's long-term exposures, we constructed cumulative parental pesticide-specific use indices for periods before and after the child's birth from data obtained using an icon-calendar-based questionnaire, of application hours (h) for plantation workers and subsistence farmers, and of kilograms of active ingredients (ai) only for subsistence farmers. Pesticide residues of TCPY, 3-PBA and 2,4-D were analysed in children's urine as indicators for current exposures. Results Life-time indices were highest for the organophosphates chlorpyrifos (median 114 h (min 2; max 1584), 19.2 kg ai (min 0.37; max 548)) and methamidophos (84 h (6; 1964), 12.2 kg ai (0.30; 780)). The P50 values of children's urinary residues were 3.7 mu g/g creatinine for TCPY, 2.8 for 3-PBA and 0.9 for 2,4-D; TCPY values are comparable with those in other countries, but 3-PBA and 2,4-D are considerably higher. The maximum levels for all three pesticides are the highest reported for children. Residues increased on days after application, but most high residue levels were unrelated to parental pesticide applications. Conclusion Urinary pesticide residues reveal high environmental exposure among children in rural Nicaragua. The quantitative parental pesticide use indices as proxies for children's exposures during different periods may be useful for the evaluation of developmental health effects.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-168563 (URN)10.1136/oem.2010.062539 (DOI)000299307700007 ()
Available from: 2012-02-15 Created: 2012-02-13 Last updated: 2017-12-07Bibliographically approved
3. Cognitive deficits in organophosphate exposed children of Nicaraguan subsistence farmers
Open this publication in new window or tab >>Cognitive deficits in organophosphate exposed children of Nicaraguan subsistence farmers
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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
organophosphates, children, pesticide, cognitive function, behavior, neurodevelopment
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine; Epidemiology
Identifiers
urn:nbn:se:uu:diva-182148 (URN)
Available from: 2012-10-04 Created: 2012-10-04 Last updated: 2012-10-29
4. Pyrethroids exposure and neurobehavioral performance in school age children in rural Nicaragua
Open this publication in new window or tab >>Pyrethroids exposure and neurobehavioral performance in school age children in rural Nicaragua
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Objective: This cross-sectional study explored whether pre or postnatal pyrethroid exposure impaired cognitive performance and behavior in school-aged children from a rural area in Nicaragua.

Methods: Pyrethroid exposure was assessed in 110 children age 7-9, attending grade 1-3, with cumulative parental pyrethroid use indices of hours of spraying, during pregnancy, the first year of life, and older than age one. Cypermethrin accounted for most of the pyrethroid use. Cognitive performance of the children was evaluated with 12 sub-tests and total IQ of Wechsler Intelligence Scale for Children (WISC IV), grouped into indices for perceptual reasoning, verbal comprehension, working memory, and processing speed. Behavior at school was measured with the oppositional, cognitive problem/inattention, hyperactivity and ADHD index subscales of the Conners’ Teacher Rating Scale-Revised:Short form (CTRS-R:S). One year later, the pyrethroid metabolite 3-PBA was measured in 211 urine samples from 74 children (median 3.3 µg/g creatinine, max. 547) and the effect of recent exposure on cognitive and behavior was assessed with a shortened battery. 

Results:

Pyrethroid exposure indices during the first year of life significantly decreased performance of perceptual reasoning in children aged 7-9. For each 10-fold increasein hours of pyrethroid application , children’s performance on the Perceptual Reasoning Index decreased on average with 1.1 point.  Postnatal exposures, during the first year and after age 1, associated with hyperactivity and attention problem. Urinary 3-PBA levels were negatively associated with a number of cognitive functions and, noteworthy, with increased scores for ADHD in girls but not in boys.

Conclusion:

Pyrethroid exposure in the first year of life was associated with decreased perceptual reasoning in rural children and with hyperactivity and ADHD predominantly in girls.

 

Keyword
pyrethroids, children, pesticide, cognitive function, agriculture, behavior, neurodevelopment
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine; Epidemiology
Identifiers
urn:nbn:se:uu:diva-182162 (URN)
Available from: 2012-10-04 Created: 2012-10-04 Last updated: 2012-10-29

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