North Carolina Reports on Birth Defects
The Occupational and Environmental Epidemiology Branch of North Carolina’s Department of Public Health issued a report in mid-May concerning the three birth defects in children born to people who work in agricultural fields, specifically those operated by Ag-Mart (see Chemically Speaking, Nov./Dec. 2005). The report described tracking the fetal time frame with respect to exposure. Although records do not reflect exact worker locations during spray operations, the mothers reported being sprayed and working in fields still wet from applications.
The report stated that between 28 and 56 days of pregnancy, the time when limbs are forming, the mother of the baby born without fully developed limbs may have been working in fields where copper hydroxide and mancozeb were applied. A literature review cited a study in which dermally applied ethylene thiourea (a metabolite of mancozeb) on female rats caused skeletal malformations of fetal bones while mothers expressed minor effects. The report concluded that this case was plausible, while the other two were less so.
The second case, a deformed jawbone, may be related to a familial trait, while the third’s malformations caused it to die soon after birth. The mother of the deceased child had given birth to a deformed stillborn child in the past, but also had four living children. The report concluded that pesticide exposure could not be ruled out for these children. In the Florida report, experts concentrated more on the similarities of the deformities, and stated they were unlikely due to chemical exposure because the deformities were so varied. (Pesticide & Toxic Chemical News, 5/29/06).
Note: This is an example of two different pathways toxicologists follow. The North Carolina study pairs retrospective exposure with results of rodent feeding studies. The Florida study was more effect based, using similarity as an indicator of pesticide exposure. While use of the two mentioned fungicides has occurred for multiple decades in the hand-harvested crop industry and they are unlikely culprits of the deformities, the fact is that there are periods in fetal development where processes are affected by chemical exposure (e.g. thalidomide). Many industries have implemented or are considering operations which place pregnant employees in non-chemical contact positions.
