Nearly six percent of infants in this country are hospitalized for an infection before they ever reach their first birthday.

Could a mother’s exposure to certain metals during pregnancy play a role in causing—or even preventing—those infections?

According to Dr. Catherine Bulka, a USF College of Public Health assistant professor who specializes in environmental and molecular epidemiology, the answer is yes.

She recently presented research showing that metals, which accumulate in and pass through the placenta, can disrupt or bolster an infant’s immune function, thereby impacting susceptibility to infections. She presented the research at the first-ever meeting of the International Society for Environmental Epidemiology’s North America Chapter (ISEE NAC).

The ISEE NAC promotes scientific research on environmental health, particularly environmental epidemiology.

“Our results showed that exposures to arsenic, a toxic metalloid, in utero, were associated with a greater risk of fever during infancy, but exposures to manganese, an essential nutrient obtained from dietary sources, counteracted that risk,” Bulka said. “Manganese is present in whole grains and vegetables. Extremely low and extremely high dietary intakes of manganese can lead to deficiency or toxicity. Our results were consistent with the idea that there is a ‘just right’ amount that provides health benefits.”

Bulka noted that some metals (in the right amounts) are hypothesized to suppress an infant’s immune system are arsenic, cadmium and lead. Those that are hypothesized to stimulate the immune system are chromium and manganese.

While Bulka and her colleagues didn’t look at how metals affect a mom-to-be or the pregnancy, per se, she said certain metals are known to be reproductive hazards.

“We know from other studies that arsenic, cadmium and lead are reproductive toxicants,” Bulka said. “Exposures have been linked to preterm birth, low birth weight, gestational diabetes, gestational hypertension, preeclampsia and other issues.”

Avoiding all harmful metals isn’t possible, but Bulka advised limiting exposure when possible.

“Cigarette smoking is a source of metal exposure, so pregnant people should avoid smoking, including exposing themselves to secondhand smoke,” she noted. “Contaminated drinking water is also a concern, especially for individuals who use private wells, as these are not nationally regulated for their metal content. Private well owners should make sure to test their water for metals, and if they are found to be at toxic levels, there are filters that can be installed to reduce exposures. And as far as exposures through food, I would suggest pregnant people eat a varied, well-balanced diet.”

Bulka noted it’s important to remember that environmental exposures don’t happen in a vacuum.

“Studying combinations of metal exposures better reflects reality,” she said. “I think my research has two implications: One, we need to be considering the role of environmental chemicals in infectious diseases and two, modifying dietary intakes or using dietary supplements may offer solutions in terms of reducing the toxic effects of environmental chemical exposures.”  

Story by Donna Campisano, USF College of Public Health