PRIO – A tool for Risk Reduction of Chemicals

Why are mutagenic substances (Category 2) priority risk-reduction substances?

Mutagenic substances in Category 2 may cause mutagenic (genotoxic) damage, but their heritability is not as well proven as for mutagenic substances in Category 1A and 1B. Mutagenic substances in Category 2 should therefore be regarded as possibly causing heritable genotoxic damage to humans. The reason why mutagenic substances in Category 2 have been emphasised as priority risk reduction substances, unlike carcinogenic substances and substances toxic to reproduction in Category 2 is that mutagenic properties can lead to heritable mutations or damage which in the long-term can cause cancer or harm to reproduction. The damage may theoretically arise after a single exposure to a very low dose of the substance. Damage from substances that are carcinogenic or toxic to reproduction in Category 2 is generally judged to occur at higher doses (at a threshold dose) or to be less well proven than for the substances in Category 1A and 1B.