NIOSH Research Program on Chemical Exposures to Help Prevent Birth Defects

Birth Defects

To learn whether exposure to potentially hazardous chemicals in the workplace increases the risk of birth defects, NIOSH researchers are partnering with the Centers for Birth Defects Research and Prevention (CBDRP) on one of the largest birth defects prevention research efforts in the nation.

NIOSH researchers hope to address some key questions:

  • Which workplace chemicals contribute to specific birth defects?
  • What level of chemical exposure contributes to birth defects?
  • When is chemical exposure likely to cause birth defects?
  • What workplace factors other than chemical exposure might be involved?

The CDC’s National Center on Birth Defects and Developmental Disabilities is funding and coordinating the research.

The first part, called the National Birth Defects Prevention Study (NBDPS), collected information from voluntary participants about health and lifestyle, including their work before and during pregnancy. Between 1997 and 2011, more than 30,000 mothers of babies with birth defects, identified through population-based birth defects surveillance systems, and 10,000 mothers of babies without birth defects participated in the study.

Recent findings from the study suggest that work-related exposure to fungicides, insecticides, and herbicides are unrelated to most birth defects of the heart that are included in NBDPS. However, researchers found a connection between a few rare heart birth defects and above-average exposure levels to some of these pesticides. For example, mothers of children with one type of birth defect were 5 times as likely as mothers of children without birth defects were to have encountered higher doses of insecticides and herbicides. This birth defect, called hypoplastic left heart syndrome, impairs normal blood flow through the heart.

The study included diverse occupations, including those involved in chemical production and use, such as agriculture, landscaping, lawn care, and pest extermination.

Researchers estimated exposures using factors that include the levels of exposure typically associated with specific types of job tasks performed by the women, how long the women held their jobs, and how many hours per week they worked—from 1 month before pregnancy through the end of their first trimester.