Examining the effects of chemical exposures on babies’ and children’s health
Even though chemicals are pervasive in our 21st century environment, we don’t know how exposure to these chemicals in utero and through breast milk affects the health and wellbeing of babies. A team of Canadian researchers, including PERU epidemiologist Dr. Linda Dodds, is shedding light on this important issue through a nationwide study involving more than 2,000 pregnant women and their babies.
“We enrolled pregnant women in the study from 2007 to 2010 and tested their blood and urine samples for indications of exposure to about 50 chemicals, including PCBs, heavy metals, flame retardants and plasticizers,” says Dr. Dodds, who leads the Nova Scotia arm of the MIREC study (Maternal-Infant Research on Environmental Chemicals), which is funded by the Canadian Institutes of Health Research, Ontario Ministry of Health and Health Canada. “Once their babies were born, the cord blood and breast milk were tested for the same chemicals. The babies were assessed at birth and at six months for growth and other developmental milestones.”
Health Canada is funding an extension of the MIREC study to look at the children’s overall burden of environmental chemical exposure and measures of physical and neurological development. “We now have an incredible cohort, with detailed information about their prenatal and early childhood exposure to common chemicals, that we can follow to trace the long-term effects,” Dr. Dodds says. “This is a unique opportunity.”
Many of the chemicals the researchers are tracking are known to cause disruption to the endocrine system – for example, the plasticizers known as phthalates. Dr. Dodds has funding from the Canadian Diabetes Association to see if early exposure to these chemicals may be linked to higher levels of fetal markers of metabolic dysfunction.
“It may not be a coincidence that we’ve seen a sharp rise in the rates of obesity and type 2 diabetes since these chemicals were introduced,” notes Dr. Dodds, who is also part of a team studying the effect of plasticizers on male reproductive health. “We need to know how these substances may be impacting human health so we can advise policymakers of potential hazards.”
Dr. Dodds’ research has already had an impact in reducing Nova Scotians’ exposure to unhealthy drinking water. In the early 2000s, she found an association between by-products of water treatment – which occur when chlorine or other disinfectants mix with excessive organic matter in the water – and higher rates of stillbirths. In response to this and other reports suggesting adverse outcomes associated with high levels of disinfection by-products, governments upgraded water treatment systems across the province.
Not all environmental exposures in pregnancy are bad. Exposure to sunshine – or supplemental vitamin D in colder climates and seasons – may be vital to healthy pregnancies and babies. Dr. Dodds has launched a new study with colleagues in Quebec to learn how much vitamin D is optimal in pregnancy to prevent complications and the potential consequences of inadequate vitamin D exposure. Exposure to vaccines in utero also seems to be positive. Dr. Dodds and her colleagues have found that both mothers and babies seem to benefit from the influenza vaccine in pregnancy.