A fungal toxin that commonly contaminates cereal grains is metabolized differently by humans and animals such as cows and pigs, scientists have found (Chem. Res. Toxicol., DOI: 10.1021/tx300348x). The discovery could help toxicologists tailor species-specific tests for exposure to the Fusarium mold toxin deoxynivalenol (shown). The toxin causes diarrhea and vomiting in humans and more serious effects such as altered immune function in pigs. Ronald Maul of the German Federal Institute for Materials Research & Testing and his colleagues exposed liver microsomes from humans and six other animal species to deoxynivalenol. They then analyzed the metabolic products using mass spectrometry. All seven species metabolize deoxynivalenol by linking it with glucuronic acid to form conjugates called glucuronides that they excrete. But the team found that different species produce different mixtures of glucuronides. Humans form up to three different types of these compounds. In contrast, rats, cows, and carp form only two of the three, and pigs and chickens form only one. These differences should be considered when choosing biomarkers for blood and urine tests of deoxynivalenol exposure, the researchers write.