Title: Study links atazine to birth defects

[MedPage Today - 28 Sept 2012 by By Crystal Phend] -- Exposure to atrazine, a common weedkiller, during pregnancy may raise the risk of a rare nasal blockage birth defect, researchers found. Women exposed to high levels of the herbicide at home were almost twice as likely to have children with choanal atresia or stenosis, Philip J. Lupo, PhD, of the University of Texas School of Public Health, and colleagues found in an observational study. The risk appeared to be dose-dependent, the group reported online in the Journal of Pediatrics. Atrazine is the most commonly used herbicide in the U.S., although the CDC's Agency for Toxic Substances and Disease Registry notes most exposure is around farms where it has been sprayed, rather than through household use. The agency recommends staying away from fields that have recently been sprayed, not swimming in or drinking from contaminated water, and not letting children play in dirt near where atrazine may have been discarded. The chemical has been shown to cause other birth defects and is linked to gastroschisis, spina bifida, cleft lip, congenital heart defects, limb reduction defects, and urogenital defects. It is also a known endocrine disruptor. ${imageDescription} Comment

Since choanal atresia is suspected to arise from maternal endocrine problems, the researchers examined the population-based Texas Birth Defects Registry for links to maternal exposure to atrazine at home during pregnancy. Atrazine exposure was estimated by the U.S. Geological Survey, which calculates exposure based on the county's annual crop acreage and type likely to have been sprayed with the chemical. Active case surveillance from 1999 through 2008 turned up 280 cases of choanal atresia or stenosis without additional major malformations or genetic syndromes. The potentially life-threatening defect blocks off the back of the nasal passage during development and often requires multiple surgeries to restore normal breathing. When compared with a random 10:1 sample of controls without major malformations delivered during the study period, children whose mothers had the highest estimated atrazine exposure at home were 1.65-fold more likely to be born with the birth defect than those with low exposure levels (95% confidence interval 1.10 to 2.48). The association actually strengthened to an odds ratio of 1.79 with adjustment for season of conception, the child's sex, birth year, and maternal factors like race or ethnicity, education, age, and smoking status (95% CI 1.17 to 2.74). Increasing exposure correlated with higher choanal atresia or stenosis risk both in the adjusted and unadjusted analyses (adjusted P=0.002). Risk of the birth defect rose 49% for each 100 pounds of atrazine used per square mile in the county (95% CI 1.09 to 2.04).

These results have to be interpreted cautiously because of the county-level estimates used due to a lack of any large-scale population-based measures of atrazine exposure in individuals, the researchers cautioned. "However, living in areas with high levels of atrazine application (e.g., proximity to agricultural fields) appears to correlate with personal exposure," they noted. "For instance, families living in farm households have higher levels of urine atrazine metabolites compared to families living in nonfarm households."

The group also cautioned that the study couldn't rule out confounding by unmeasured variables.

"Thus, the present study is an important first step in determining what associations may be present," they wrote. "Future research is needed to confirm our findings, using other exposure assessment methodologies, including biomarkers of exposure."

The study was supported in part by the CDC-funded Texas Center for Birth Defects Research and Prevention through a cooperative agreement with the Texas Department of State Health Services, as well as the Title V Office of Texas.

The researchers reported having no conflicts of interest to disclose.



Source reference:
Agopian AJ, et al. "Maternal residential atrazine exposure and risk for choanal atresia and stenosis in offspring" J Pediatr 2012; DOI: 10.1016/j.jpeds.2012.08.012.

Original source





Article: WeedsNews3815 (permalink)
Categories: :WeedsNews:herbicides, :WeedsNews:health, :WeedsNews:research alert
Date: 3 October 2012; 9:21:33 PM AEST

Author Name: David Low
Author ID: adminDavid