The Characteristics of PCDD/F and PCB Occurrence and the Effect of Age in Matched Tissues of Cattle and Sheep from Southern Italy

< 0.01) in the liver relative to muscle. A characteristic occurrence pattern showed PCBs dominating the combined toxic equivalence (TEQ) by >95% in cattle tissues and 78% and 67% in sheep muscle and liver, respectively. A majority of liver samples exceeded regulated maximum limits, and the herds were excluded from the food supply. Subsequent regional monitoring showed regulatory compliance of cattle/sheep meat and liver, but prominence of PCB-TEQ persisted. Concentrations of both contaminants declined strongly in the tissues of both species with increasing age of juveniles but stabilized in older animals (>one year in sheep; 2/3 years in cattle). Although weight gain might partly account for this pattern, the initial decline may also relate to inadequate levels of CYP enzymes in the youngest juveniles, but this would need to be confirmed in both species by targeted toxicokinetic studies during this perinatal period. The expression of these detoxifying enzymes is reported to rise rapidly with increasing postnatal age in many animal species, including sheep.