Every chemical the public is exposed to is thoroughly tested and carefully regulated to ensure it doesn’t pose a risk to public health. Whether it’s a food ingredient, industrial chemical or a weedkiller used in home gardens, the manufacturer is obligated to demonstrate its safety to federal officials. 

Environmental activists recognize this basic fact as a serious threat to their anti-chemical scare campaigns and concoct increasingly strained excuses to explain why exposure to low-risk chemicals is actually very dangerous. Their favorite sleight of hand in recent years has been what we call the “cumulative exposures gambit.”

The idea is that exposure to multiple chemicals can be dangerous, even if each one has been declared safe as used by the Environmental Protection Agency (EPA). It’s a highly misleading claim. Let’s use this recent blog post from the Environmental Defense Fund (EDF) to illustrate why. EDF’s key assertion is that:

“Communities near industrial facilities are often exposed to multiple chemicals that cause the same health effects. Evaluating the health risk of these chemicals individually, as currently done by [the EPA], often underestimates the true risks communities face.”

This is false for several important reasons.The first problem is that EDF wrongly assumes (rather than demonstrates) that some individual chemicals “cause the same health effects,” and therefore deceptively concludes that combining them is even more dangerous. 

Ignoring facts about vinyl chloride

For instance, the activist group asserts that vinyl chloride – a chemical used to manufacture PVC plastic – is carcinogenic, so exposure to it and “other carcinogenic chemicals” amplifies someone’s risk of cancer. But as we have explained too many times to count, the public is exposed to so little vinyl chloride that it can’t possibly pose a cancer risk.

 Even inside PVC manufacturing facilities – where workplace exposure to vinyl chloride would arguably be the highest of anywhere on the planet – cancers with a unique association to the chemical are nonexistent today.

If the activists at EDF believe that vinyl chloride contributes to some cumulative risk, they have an obligation to explain why. Speculations and assertions just aren’t good enough.

Second, the EPA has had an extensive framework in place to examine the impact of cumulative chemical exposures for many years. This approach “includes developing profiles of exposure, considering interactions (if any) among stressors, and predicting risks to the population or populations assessed,” the agency notes in a 130-page report published over two decades ago. EDF’s complaints are badly out of date in 2024.  

Finally, the EPA regulates chemicals under multiple federal laws.These regulations provide the agency with a wide variety of tools to protect public health by setting strict limits on chemical contaminants in drinking water, ambient air and commercially available products. Put simply, the EPA can and does limit the public’s cumulative exposure to chemicals.

Conclusion

EDF and other activist NGOs have misapplied a valid concept to advance their ideological goal of banning chemicals with important public health and industrial applications. Exposure to multiple substances can be dangerous.That’s why it’s usually a bad idea to mix cleaning products, for example, and why the EPA has issued chemical compatibility guidelines. But we only know about the potential harm of mixing different substances because experts have thoroughly tested these chemistries to see how they interact with each other. 

As usual, the lesson for interested members of the public is simple: learn science from scientists; ignore activists who exist only to scare you.