Biomonitoring of human exposure to carcinogenic nitroaromatic compounds: a pilot study on DNA adduct formation by 1,6-dinitropyrene in rats

DNA adduct formation by 1,6-dinitropyrene (DNP) was examined in various rat tissues. Intraperitoneal administration of 0.2, 1.0 or 5.0 mg DNP/kg b.w. caused the formation of one major and, at the higher doses, two minor DNA adducts. The highest level of about 300 adducts/10(9) nucleotides was found in urinary bladder DNA. 5-10-fold lower adduct levels were found in the DNA of white blood cells (WBC), liver, lung and small intestinal mucosa. DNA adduct levels in the bladder were highest in Sprague-Dawley males followed by Sprague-Dawley females and Wistar males. Administration by gavage was less effective than intraperitoneal injection. Intratracheal instillation of microcrystalline DNA suspensions did not lead to any detectable adduct formation. The results indicate that WBC DNA may not be a reliable DNA source for biomonitoring human exposure to nitroarenes and that nitroarene-DNA adducts may only be detectable at high levels of exposure.