The Center for Environmental Health (CEH) announced plans Wednesday to take legal action against 19 electronic cigarette manufacturers.

The California-based consumer safety group said it conducted independent tests and found that one or more products from each company produced high levels of either formaldehyde or acetaldehyde, or both, two chemicals that cause cancer and have been linked to genetic damage, birth defects, and reduced fertility.

The CEH says the companies, which include RJ Reynolds, ITG Brands LLC and NJOY Inc, violated California’s consumer protection law known as Proposition 65, by failing to warn consumers about the significant amount of chemicals in their products.