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By: Kaley Beins

“In order to protect public health from chemical contamination, there needs to be a massive outcry–a choir of voices–by the American people demanding change.” When Lois Gibbs reflected on her 20 years of environmental health activism she wrote this call to action in the context of her activism in Love Canal, NY, the birthplace of EPA Superfund legislation. Now, almost 40 years after the legislation was passed, Americans still face the consequences of toxic exposures from waste sites, industrial pollution, and even consumer products. Movies like Erin Brockovich and Dark Waters dramatize industry contamination of communities, while news stories like the Flint water crisis demonstrate the prevalence of toxic exposures, especially for low income communities and communities of color. 

Yet, legislation to prevent such exposures often dies in committee or, worse, on the lips of the politicians espousing it. While we wait for updated and implemented toxics regulations, we can educate ourselves about environmental health and advocate for policies to prevent, or at least mitigate, toxic exposures. 

One of the trickier parts of being informed is understanding how researchers and government agencies define the exposure levels associated with human health effects. Some evaluations, such as IARC and EPA carcinogenicity classifications, are based on the amount of available data from animal and human studies. However, in my opinion, the most meaningful information on chemical exposures is based on exposure dose, or the amount of a chemical you are exposed to. Unfortunately, these values will vary between agencies, but by knowing how exposure limits are determined, you can better understand how protective (or permissive) environmental policies and guidelines are. 

The largest distinction between set exposure limits in the United States is whether or not they are legally enforceable. Legally enforceable limits are upheld by law and are usually determined by the U.S. EPA, Occupational Safety and Health Administration (OSHA), and state agencies. Non-regulatory agencies like the Centers for Disease Control and Prevention (CDC) and the National Institute for Occupational Safety and Health (NIOSH) publish research and guidelines on chemical exposure limits, but these limits are not legally enforceable. The following is a non-exhaustive list of some federal exposure limits and how they’re determined: 

Enforceable: 

  • EPA National Ambient Air Quality Standards (NAAQS) are measures of allowable air pollution for 6 criteria air pollutants as permitted under the Clean Air Act. 
  • EPA Maximum Contaminant Level (MCL) is the legal limit for chemicals in drinking water, as enforced by EPA. When determining MRLs, EPA considers the cost and technology required to remove contaminants in addition to the available health data.
  • OSHA Permissible Exposure Limits (PELs) are levels of exposure allowed for workers over the course of the work day. 

Not enforceable 

  • ATSDR Minimal Risk Levels (MRLs) are levels derived from toxicological studies in humans or animals. 
  • EPA Maximum Contaminant Level Goal (MCLG) is the limit for chemicals in drinking water below which no human health effects are expected to occur. Not to be confused with MCLs, MCLGs are determined only using health data. They may be slightly lower than MCLs. 
  • NIOSH Recommended Exposure Limits (RELs) are levels of exposure that NIOSH recommends workers do not meet or exceed during the work day. RELS are often used to help determine OSHA PELs.

The differences between these values can inform how you and your community use them. However, many chemicals may not have any exposure limits, either because they are not regulated or because insufficient health data exist. Nevertheless, information about chemical exposure levels and the risks associated with them is crucial in promoting environmental health. The following resources can help you stay informed about environmental health risks in your community:

As you engage with contamination issues in and outside your community, you can use these resources to arm yourself with information, then organize locally, collaborate nationally, engage politically, and stay involved. As Baltimore activist Destiny Watford said in an interview, “I realized it is important to question why people invested in something, why things are the way they are, and what can I do to change things in a way that isn’t superficial but gets to the root of the problem.” 

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Kaley Beins, MPH is an environmental health researcher who works at the intersection of public health and toxicology. During her career she’s worked with nonprofits, local health departments, and federal agencies, and she’s learned the ins and outs of chemical regulation and exposure, as well as how much of that information is available to the public. Kaley is passionate about education and empowerment as an avenue for environmental justice and health equity. 

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