The substances cadaverine and putrescine are produced during the decomposition of animal (including human) bodies, and both give off a foul odor. They are toxic if massive doses are ingested (acute oral toxicity of 2 g per kg of body weight of pure putrescine in rats, a larger dose for cadaverine); there are no effects at all for a tenth of that dose. While figures for humans are not available, allometric scaling, which takes into account body surface area, is often used to compare doses in different animals, with useful results. Scaling 2g/kg from rats suggests that a 60 kg (132 lb) person would be significantly affected by of pure putrescine. For comparison the similar substance spermine, found in semen, is over 3 times as toxic.