22. Exposure to organophosphorus and organochlorine pesticides, perfluoroalkyl substances, and polychlorinated biphenyls in pregnancy and the association with impaired glucose tolerance and gestational diabetes mellitus: the MIREC Study (lay summary)

Shapiro GD, Dodds L, Arbuckle TE, Ashley-Martin J, Ettinger AS, Fisher M, Taback S, Bouchard MF, Monnier P, Dallaire R, Morisset AS, Fraser WD. Environmental Research. 2016 Feb 4;147:71-81. doi: 10.1016/j.envres.2016.01.040

Gestational diabetes is a condition that can develop in pregnant women who did not have diabetes before the pregnancy began.  Women with gestational diabetes have high blood glucose (sugar) levels during pregnancy.  Environmental chemicals may play a role in increasing the risks of having gestational diabetes.  Some chemicals like organochlorine pesticides and polychlorinated biphenyls (PCBs) have been banned but still persist in the environment.  Other chemicals such as organophosphate pesticides and perfluoroalkyl substances (used in the production of common household and consumer goods including cookware, clothing, and food packaging) may continue to be used.

In this MIREC study, data on 1274 pregnant women were available to examine if exposure to these chemicals was associated with the risk of gestational diabetes.  Maternal blood and urine samples were collected during the first trimester of pregnancy and analysed for these chemicals. Gestational diabetes was assessed based on the woman’s glucose test results and her medical records.

The study found that women with the highest urine levels of two organophosphorus pesticides were less likely to have gestational diabetes compared to women with the lowest levels of these pesticides. The reason why women in this study who had higher levels of organophosphorus pesticides were less likely to have gestational diabetes is unknown.  It may be because they were exposed to these pesticides from eating fruits and vegetables that protect against diabetes. None of the chemicals measured were associated with increased risk of gestational diabetes.

The results of this study will be used to better understand the environmental factors that may play a role in gestational diabetes.