Authors
Garry VF, Harkins ME, Erickson LL, Long-Simpson LK, Holland SE, Burroughs BL..

Title
Birth Defects, Season of Conception, and Sex of Children Born to Pesticide Applicators Living in the Red River Valley of Minnesota, USA

Journal
Environ Health Perspect. 2002 110 Suppl 3:441-9

Summary
The Red River Valley (RRV) region of Minnesota is a major wheat, sugar beet, and potato crop-growing region that uses pesticides including fungicides and chorophenoxy herbicides at times. In an earlier study, Garry et al found that the Red River Valley (RRV) region of Minnesota had a higher age-adjusted birth defect incidence rate than urban regions in Minnesota. Furthermore, pesticide applicators of this region had elevated age-adjusted birth defect incidence rates and an increased ratio of male to female children with birth defects compared to the general population of the RRV. Their current cross-sectional study was designed to collect more detailed information on the incidence, recurrence (two or more affected children in same family), seasonal variation and sex-ratio of infants with birth defects in the offspring of pesticide applicators and their families.

In Minnesota, applicators must have licenses for specific classes of pesticides. Garry et al obtained a list of 3000 licenses between 1991 and 1996 and randomly chose 1500 in the Minnesota RRV region. There were 1070 applicators who volunteered to participate (98% male) in a phone interview. Over 850 pesticide applicators had partners of which 802 (women) participated in the initial survey. The applicator and his partner were interviewed on their general health and pesticide use and all subjects were invited to participate in a subsequent written reproductive health and pesticide use assessment questionnaire. In the end, there were 695 couples with at least one member responding to this questionnaire. Live births fathered by 536 pesticide applicator were eligible for the study. There were 1532 births with parent-reported defects. Birth defects were followed-up through medical records examinations and birth certificates. Families that reported multiple children with birth anomalies had a follow-up questionnaire and brief interview to obtain detailed familial histories. The occurrence of birth anomalies and similar anomalies among blood relatives (parents, siblings, and children of siblings) was collected and a pedigree was developed that specified birth anomalies, cause of death, and age at death. Pesticide appliers were interviewed by phone regarding their current and past use and again 6 months later by written questionnaire to validate the class of pesticide used. The spouse was similarly interviewed and followed-up with a written questionnaire.

Among the 1532 live births fathered by a pesticide applicator, 70 infants had one or more birth defects (77% confirmed by medical records). Siblings from 5 of the 12 families with recurrent birth defects had the same or similar birth defects, suggesting familial susceptibility.

Applicator exposure was assessed according to specific pesticide class using the groups: i) herbicide, insecticide, fumigant ii) herbicide, insecticide, fungicide; iii) herbicide, insecticide; iv) other; v) use of all four classes of pesticides vi) herbicides only. Pesticide applicators who applied only herbicides were used as the referent group. The authors did not find significant differences in birth defect rates among these exposure groups but over 15% of the applicators who applied fumigants, insecticides, and herbicides had at least one child with a birth defect compared with 6.8% in the referent group. Applicators who applied phosphine fumigants compared to the referent were at increased risk of having children with birth defects (OR=2.3, CI=0.9-6.1), as well as central nervous system or neurobehavioral problems (OR=2.5, CI=1.2-5.1). Four of the 14 children with birth defects involving the central nervous system, and both children with Autism were born to fathers that applied phosphine. Furthermore, 5/14 children with parent-reported Attention Deficit Disorder/Attention Deficit Hypertension Disorder (ADD/ADHD) had a father who applied phosphine and 43% percent of children who had parent-reported ADD/ADHD had fathers who used phosphonamino herbicides (OR=3.6, CI=1.4-9.7). Regarding sex ratio, this study revealed that more male children were born to families whose male partner did not apply fungicides than to those who did apply fungicides (p=0.04). If male partners did not apply fungicides, there were more male children born (M/F sex ratio=1.8) with birth defects while if fungicides were applied there were fewer male children born with birth defects (M/F sex ratio=0.57, p=0.02). Fertility was not a factor in these results because the birth rates were the same for families who applied fungicides and herbicides. Finally, similar to their previous study, the authors found that children conceived in the spring, when herbicides are routinely applied, had significantly higher numbers of birth defects (p=0.02).

Although the sample size of this study was small, the data suggest that certain pesticides may have an adverse effect on fetal development, sex ratio and neurological outcomes in children. Further investigation into the mechanisms by which these effects occur would be warranted. The role, if any, of endocrine disruption in these apparent effects remains unknown.

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