One could posit that inserting a penis into a vagina stands as least as much of a chance of disrupting the environment as inserting fingers would If a woman is using FA for birth control it d be almost impossible to determine whether the fingers or the penis were causing a change Plenty of women regularly masturbate with fingers inserted vaginally or allow partners to masturbate them with fingers inserted vaginally I think the current mention of possible environmental changes through digital penetration is enough I say don t cite it