Chemicals found in thirdhand smoke that are identified by California’s Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) to cause cancer, birth defects or other reproductive harm, and their classification by the IARC18 69 84 91 120–130
| Name of chemical | CAS* number | Type of toxicity (Proposition 65)† |
| IARC classification 1: carcinogenic to humans | ||
| Benzene | 71-43-2 | Cancer, developmental, male reproductive |
| Benzo(a)pyrene | 50-32-8 | Cancer |
| Cadmium | 7440-43-9 | Cancer, developmental, male reproductive |
| Formaldehyde | 50-00-0 | Cancer |
| NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone | 64091-91-4 | Cancer |
| NNN, N-nitrosonornicotine | 16543-55-8 | Cancer |
| IARC classification 2A: probably carcinogenic to humans | ||
| Dibenz(a,h)anthracene | 53-70-3 | Cancer |
| Dichloromethane or methylene chloride | 75-09-2 | Cancer |
| Styrene | 100-42-5 | Cancer |
| IARC classification 2B: possibly carcinogenic to humans | ||
| Acetaldehyde | 75-07-0 | Cancer |
| Acrylonitrile | 107-13-1 | Cancer |
| Benz[a]anthracene | 56-55-3 | Cancer |
| Benzo(b)fluoranthene | 205-99-2 | Cancer |
| Benzo(k)fluoranthene | 207-08-9 | Cancer |
| Chrysene | 218-01-9 | Cancer |
| Ethylbenzene | 100-41-4 | Cancer |
| Furan | 110-00-9 | Cancer |
| Furfuryl alcohol | 98-00-0 | Cancer |
| Indeno(1,2,3-cd)pyrene | 193-39-5 | Cancer |
| Isoprene | 78-79-5 | Cancer |
| Lead | 7439-92-1 | Cancer, developmental, female and male reproductive |
| N-nitrosopyrrolidine | 930-55-2 | Cancer |
| Naphthalene | 91-20-3 | Cancer |
| Pyridine | 110-86-1 | Cancer |
| IARC classification 3: not classified as to its carcinogenicity to humans | ||
| Toluene | 108-88-3 | Developmental |
| California Proposition 65 classified only | ||
| Nicotine | 54-11-5 | Developmental |
*CAS number: Chemical Abstract Service number, a unique identifying number for chemical compounds.
†Proposition 65 requires the state of California to maintain and update a list of chemicals known to the state to cause cancer, birth defects or reproductive harm.
IARC, International Agency for Research on Cancer (WHO); NNK, nicotine-derived nitrosamine ketone.