A number of the toxic substances found in diesel engine exhaust are “known carcinogens.” Toxic substances found in engine exhausts that have been evaluated for carcinogenicity to humans by the International Agency for Research on Cancer (IARC) (IARC 2014) are outlined below. These substances have been classified by IARC as Group 1 (the agent is carcinogenic to humans), Group 2A (the agent is probably carcinogenic to humans), and Group 2B (the agent is possibly carcinogenic to humans). See Table 1 for detailed information.
So, when you consider that diesel exhaust is composed of a bunch of different known or probable carcinogens, it should come as no surprise that the scientific and medical fields have finally deemed diesel exhaust a carcinogen.
| Table 1 | ||
| Toxic Substances Identified in Diesel and Gasoline Engine Exhaust | ||
| and Their Respective IARC Carcinogenic Classifications | ||
| Agent Name | CAS No. | Classification (Group) |
| Metals | ||
| Antimony compounds (Trioxide) | 1309-64-4 | Group 2B |
| Arsenic and inorganic arsenic compounds | 007440-38-2 | Group 1 |
| Beryllium and beryllium compounds | 007440-41-7 | Group 1 |
| Cadmium and cadmium compounds | 007440-43-9 | Group 1 |
| Chromium (VI) | 018540-29-9 | Group 1 |
| Cobalt and cobalt compounds | 007440-48-4 | Group 2B |
| Lead compounds | Inorganic | Group 2B |
| Nickel (Metallic) | Group 2B | |
| Nickel Compounds | Group 1 | |
| Organic Chemicals | ||
| 1,3-Butadiene | 106-99-0 | Group 1 |
| Acetaldehyde | 75-07-0 | Group 2B |
| Benzene | 71-43-2 1 | Group 1 |
| Bis(ethylhexyl)phthalate | 117-81-7 | Group 2B |
| Ethylbenzene | 100-41-4 | Group 2B |
| Formaldehyde | 50-00-0 | Group 1 |
| Propylene oxide | 75-56-9 | Group 2B |
| Halogenated and Other Chemicals | ||
| Dioxin/Dibenzofurans | 1746-01-6 (TCDD)* | Group 1 |
| Polycyclic aromatic hydrocarbons (PAHs) | ||
| Benz[a]anthracene | 56-55-3 | Group 2B |
| Benzo[b]fluoranthene | 205-99-2 | Group 2B |
| Benzo[k]fluoranthene | 207-08-9 | Group 2B |
| Benzo[a]pyrene | 5-32-8 | Group 1 |
| Chrysene | 218-01-9 | Group 2B |
| Dibenz[a,h]anthracene | 53-70-3 | Group 2A |
| 3,7-Dinitrofluoranthene | 105735-71-5 | Group 2B |
| 3,9-Dinitrofluoranthene | 22506-53-2 | Group 2B |
| 1,3-Dinitropyrene | 75321-20-9 | Group 2B |
| 1,6-Dinitropyrene | 42397-64-8 | Group 2B |
| 1,8-Dinitropyrene | 42397-64-9 | Group 2B |
| Indeno[1,2,3-cd]pyrene | 193-39-5 | Group 2B |
| Naphthalene | 91-20-3 | Group 2B |
| Nitroarenes | ||
| 3-Nitrobenzanthrone | 17 117-34-9 | Group 2B |
| 6-Nitrochrysene | 7496-02-8 | Group 2A |
| 2-Nitrofluorene | 607-57-8 | Group 2B |
| 1-Nitropyrene | 5522-43-0 | Group 2A |
| 4-Nitropyrene | 57835-92-4 | Group 2B |
| Styrene | 100-42-5 | Group 2B |
| *TCDD (2,3,7,8-tetrachlorodibenzo-para-dioxin); Table 2 adapted from Table 1.2 in IARC Monograph 105, 2014 |
