The Collaborative International Dictionary
mutagenicity
mutagenicity \mu`ta*gen*i"ci*ty\, n. the degree or measure of the ability to cause mutation[3]; -- said of mutagens.
Wiktionary
mutagenicity
n. 1 (context uncountable English) The condition of being mutagenic 2 (context countable English) A measure of the extent to which something is mutagenic