Genotoxic potential was shown in bacteria and mammalian cell system, micronucleus formation occurred in bone marrow cells. Actual cancer incidence increase was clearly observed too: The same study finding bronchitis after long term respiratory use, found that 81% of mice had lung adenomas(8% in control), 27% skin adenomas (0% in control), 11% malignant lymphomas (0% in control). Similar studies also showed significant carcinogenicity. This shows that even though long-term inhalation damages the lungs, it also increases cancer risk, which is a risk needing stricter regulation.