The Reference Dose for Bisphenol-A

Although a number of groups state otherwise, there is only one generally accepted guideline regarding safe bisphenol-a exposure - the Reference Dose for Chronic Oral Exposure (RfD) as established by the EPA. In short, the reference dose is the amount of a chemical a person can take in on a daily basis without it having any harmful effects, measured in milligram of substance per kilogram of body mass per day. The recommended dose for bisphenol-a is 0.05 mg/kg/day.

The reference doses for all chemicals are determined experimentally. To find the RfD for bisphenol-a, scientists fed animals varying amounts of the chemical to see at what point they could observe adverse effects. This point, known as the Lowest Observed Adverse Effect Level (LOAEL), was established to be 50 mg/kg/day in rats, at which point the F1 (second) generation became underweight, and 130 mg/kg/day in mice, at which point the scientists found an increased number of multinucleated giant hepatocytes (abnormal liver cells). Tests were also conducted on dogs, but no serious adverse effects were found.

With this information, the EPA determined the RfD of bisphenol-a to be 0.05 mg/kg/day. Despite the varying LOAEL’s, the EPA is confident in its results. It feels that its investigation was sufficiently complete and that there is little reason to believe that the RfD should be lower. Therefore, the consumer should have confidence that any government-approved products containing bisphenol-a are safe for regular usage.