Do Occupational Exposure Limits (OELs) Really Protect Workers from Reproductive and Developmental Effects?

The United States Census Bureau indicates that over 66 percent of pregnant women continue to work throughout their pregnancy. This rate has significantly increased since the 1960s, when only 44 percent of pregnant women were in the workforce.  Given this trend, the potential impact of workplace chemical exposures on reproduction and development is an increasing concern. This concern involves not only exposures of pregnant women but also of male and female workers prior to conception.

Findings from OELs Studies

1. Exposure concern is not just for pregnant women but also for men and women prior to conception because of potential Developmental And Reproductive Toxicity (DART) effects in both. Furthermore, because infants may be exposed to chemicals via breast milk, the period of concern for developmental toxicity does not cease at birth. 

2. Tests to determine OELs are performed on animals not humans, usually animal inhalation studies.

3. Tests use limited numbers of subjects and do not factor in simultaneous exposures to multiple chemicals.

4. There are "Windows of Susceptibility" where fetal development may be disrupted by chemical exposures. A developing organism is most susceptible to chemical damage during fairly narrow timeframes.

5. Scientific rationales for setting OELs are often limited and aimed at minimizing or preventing "acute" exposures to healthy adults and do not include consideration of potential DART effects. 

6. Most OELs are expressed as time weighted averages but numerous studies have indicated that peak concentration in maternal blood is more important for determining developmental effects than average exposure, likely because a short high-level exposure may overwhelm maternal metabolism and allow fetal exposures in a way that lower level exposures may not.

Many workers are understandably concerned about the risk of workplace chemicals adversely affecting their child during pregnancy or their ability to conceive. To address these concerns, it is not enough to simply check that all exposures are below available OELs. Industrial hygienists should carefully review the basis of existing OELs or, when OELs are completely lacking, take advantage of available tools and expert advice to establish new ones that take into account DART effects. Routine evaluation of potential DART risks should be part of every health and safety program.  

Many women (and to a lesser degree, men) are working in hospital sterile processing departments either directly or in close proximity to toxic chemical sterilants. Without a gas monitor, workers have no way of knowing the level of chemical sterilant vapors that they are potentially exposed to.