Birth Defects among Offspring of Norwegian Farmers, 1967-1991

Abstract

We investigated birth defects (N = 4,565) reported to the Medical Birth Registry of Norway among 192,417 births between 1967 and 1991 to parents identified as farmers in five agricultural and horticultural censuses between 1969 and 1989. The prevalences at birth of all and specific birth defects deviated little from those among 61,351 births to non-farmers in agricultural municipalities. We classified exposure indicators on the basis of information provided at the agricultural censuses. The main hypotheses were that parental exposure to pesticides was associated with defects of the central nervous system, orofacial clefts, some male genital defects, and limb reduction defects. We found moderate increases in risk for spina bifida and hydrocephaly, the associations being strongest for exposure to pesticides in orchards or greenhouses [spina bifida: 5 exposed cases, odds ratio (OR) = 2.76, 95% confidence interval (CI) = 1.07-7.13; hydrocephaly: 5 exposed cases, OR = 3.49, 95% CI = 1.34-9.09]. Exposure to pesticides, in particular in grain farming, was also associated with limb reduction defects (OR = 2.50; 95% CI = 1.06-5.90). We also saw an association with pesticides for cryptorchism and hypospadias. We found less striking associations for other specific defects and pesticide indicators, animal farming, and fertilizer regimens.

Hypospadias: Interactions between environment and genetics

“…Two epidemiological studies reported a possible relationship between exposure to pesticides and hypospadias. Kristensen reported a moderate increase in the odds ratio (OR) for hypospadias in individuals exposed to farm chemicals (OR = 1.51, 95% confidence interval, 1.00-2.26) [66], and Weidner [67,68] A c c e p t e d M a n u s c r i p t sites has been associated with a high incidence of hypospadias [69,70]. Similarly, an increased rate of hypospadias was reported in boys from parents exposed to dioxin after the Seveso industrial accident [71].…”

Hypospadias and endocrine disruption: is there a connection?

“…In a Danish study looking at cryptorchidism and hypospadias in the offspring of farmers and women gardeners, Weidner et al (94) found no risk for hypospadias but an increase for cryptorchidism. A Norwegian study looking at 192,417 births between 1967 and 1991, where the parents were identified as farmers, revealed an odds ratio of 1 for hypospadias (95). However, between 1967 and 1971, the odds increased to 2.06 among tractor sprayers.…”

Developmental toxicity of a commercial herbicide mixture in mice: I. Effects on embryo implantation and litter size.

“…Pastore et al (1997) showed a clear positive association between occupational exposure to pesticides, especially during early pregnancy, and the risk of stillbirths in California, and Kristensen et al (1997), associated central nervous system and limb defects with parental use of pesticide spraying equipment in Norway. In contrast, a case-control study in Holland determined little effect of pesticide exposure on the incidence of central nervous system defects in children of mothers involved in agricultural activities (Blatter et al 1996); environmental pollution with pesticides, regardless of the occupation of the mother, could have explained the increased risk of spina bifida found in this study.…”