(Beyond Pesticides, June 20, 2011) In a study published this week in the journal Pediatrics, researchers report findings that link mothers’ exposure to organochlorine pesticides during pregnancy with infants’ sizes at birth. The trend shows that the more mothers are exposed to the pesticides during pregnancy, the higher the chances are for reduced birth weight and length of their newborns.
Comprising a total of 494 women and infants in Valencia, Spain from the years 2003-2006, the study evaluates umbilical cord blood for residues of four pesticides or pesticide degradates: DDT, DDE, hexachlorobenzene (HCB), and beta-hexachlorocyclohexane. The results show that a 10-fold increase in pesticide concentrations in the blood corresponds to a reduction in birth weight of 2-4 ounces.
Additional results are correlated to specific pesticides. Higher concentrations of DDT results in a reduction in head circumference of 0.26cm, which the researchers call a “significant decrease.” Additionally, a decrease of 0.39cm in birth length is correlated with each 10-fold increase in concentration of HCB.
The researchers note several concerns related to the findings, aside from the results themselves. Since people are exposed to a wide variety of chemicals in general throughout their everyday lives, higher pesticide exposure could betray higher exposure to many other different kinds of chemicals as well. Importantly, the team also points out that the findings show that high pesticide exposure is not required in order for effects to manifest. The women and newborns in the study were exposed only to moderate levels of pesticides, not extreme levels. This supports other research findings that low dose exposures, even those within federal regulatory limits, can result in serious problems for human health.
The team suggests that the changes are due to the chemicals’ interference with hormones of the thyroid, a part of the endocrine system which regulates growth and development. Disruption of the endocrine system is a common side effect of pesticide exposure, especially at low doses. Since hormones play such an essential role in many different systems throughout the body, interference in their delivery can result in myriad effects including reproductive disorders, Parkinson’s disease, and cancer.
Organochlorine pesticides such as DDT are highly persistent in the environment and, though many have been banned in the U.S. for some time, people continue to be routinely exposed to them. For the present study, the researchers that the most likely route of exposure is still through diet, presumably from food grown in contaminated soil which once was sprayed with the compounds.
Numerous pesticides have been linked to birth defects, developmental disorders, and other effects on newborns. Our Pesticide Induced Diseases Database contains an exhaustive listing of clinical studies showing these links, as well as links to a wide range of other adverse health effects concerning pesticide exposure.