McMaster University

McMaster University

Faculty of
Health Sciences

Study looks at exposure to environmental chemicals during pregnancy

Published: May 7, 2009
Warren Foster
Dr. Warren Foster, a professor of obstetrics and gynecology

McMaster researchers are recruiting 200 Hamilton women in their first trimester of pregnancy as part of a national study examining how the environmental chemicals we come across in everyday life affect our health.

Scientists will be collecting data on them and 1,800 other women in 10 Canadian cities for five years as part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Researchers will follow women throughout their pregnancy and up to eight weeks after giving birth.

Biological markers of environmental chemicals — and exposure to tobacco smoke — will be measured in the mothers’ blood, urine, hair and breast milk and in their babies’ umbilical cord blood and meconium (the baby’s first stool).  Mothers will be asked to complete questionnaires throughout pregnancy and after birth.

It’s the largest initiative ever undertaken in Canada associating a broad spectrum of environmental contaminants with health outcomes, says Dr. Warren Foster, a professor of obstetrics and gynecology in the Michael G. DeGroote School of Medicine at McMaster University and lead researcher of the Hamilton arm of the study.

Early results are expected to pinpoint links between environmental chemicals and gestational diabetes, hypertension in pregnancy, interuterine growth delay and low birth weight, and whether children with greater exposure to environmental chemicals suffer more neurological and developmental problems.

"In the longer term, it will give us a cohort of children we could come back to in five or 10 years and look at whether exposure in utero increases the risk of developmental abnormalities, advanced sexual maturation or fertility problems as they get older," said Foster.

As early as childhood, an environmental chemical — such as lead — might be picked up in a playground. Over a lifetime, lead can accumulate in the body as the growing child is exposed to everything from lead-based paints in their home to toys from China, dust, vinyl blinds and pipes.

"When a woman is pregnant, she will be exposing her developing fetus to lead and other chemicals that she has been exposed to and stored in her body," said Foster. "The most sensitive target system is the brain and neurodevelopment. Very small levels of lead are thought to be toxic to the developing neurological system and could have an effect on things like IQ (intelligence)."

The MIREC study will measure heavy metals such as lead, mercury, arsenic, manganese and cadmium, as well as other chemicals including: phthalates and bisphenol A — used to make plastics and vinyl.

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