Based on studies of liver cancer in rats, the United States Environmental Protection
Agency (US/EPA) in their Drinking Water Criteria Document for Polychlorinated
Biphenyls (PCBs) has calculated life-time cancer risks of 10-4, 10-5 and 10-6 for water
concentrations of 0.5, 0.05 and 0.005 μg Aroclor 1260 per litre, respectively (US/EPA
1990). It should be noted that this calculation is made for Aroclor 1260 only. Due to a
deficient data base on toxicity and exposure to PCBs from drinking water in the US,
recommendations for guidelines were not made for shorter exposure times.