Environmental Safety

Bisphenol A Environmental Exposure in Aquatic Ecosystems

Bisphenol A does not accumulate in aquatic organisms to any appreciable extent and is not classified as bioaccumulative by the U.S. Environmental Protection Agency. In tests of 42-days duration, measured ratios of BPA in fish to that in the surrounding water (bioconcentration factors) range from 5.1 to 68 (Staples et al, 1998). In a freshwater clam, bioconcentration factors in the range of 110-144 were measured at low temperatures (Heinonen et al, 2002). Bioconcentration factors less than 100 are considered to indicate a low potential for bioaccumulation. A bioconcentration factor of 1000 has been considered a threshold for concern, while factors greater than 5000 suggest that a substance is persistent in the environment.

Acute toxicity levels for BPA, defined as the concentration at which half of the organisms survive (LC50 values), have been measured in a variety of aquatic organisms, including freshwater and saltwater algae, invertebrates (daphnids and mysid shrimp) and fish. LC50 values range from 1000 to 20,000 micrograms/L (Staples et al, 1998; Staples et al, 2002).

The No-Observed-Effect-Concentration (NOEC) of BPA in a 21-day chronic reproduction test in Daphnia was 3160 microgram/L (Caspers, 1998). Effect concentrations at the 10% level (EC10) were determined for both freshwater and marine algae to be 1360 to 1680 micrograms/L and 400 to 690 micrograms/L, respectively (Alexander et al, 1988).

The results of a multi-generation study on fathead minnows showed that survival, growth and reproductive fitness for three generations were affected only at concentrations of 640 micrograms/L and higher, with hatchability of F2 (second generation) eggs slightly reduced at 160 micrograms/L. The NOEC measured in this study was 16 micrograms/L. (Sohoni et al, 2001; Caunter, 2000).

A weight-of-evidence analysis of the aquatic hazards posed by BPA was conducted with a focus on validated studies and the ecologically relevant endpoints of survival, growth and reproductive fitness. This analysis included the use of statistical extrapolation techniques to assess the full database of reported effect concentrations. The study concludes that no adverse aquatic effects are expected at concentrations below 100 micrograms/L of BPA (Staples et al, 2002).

Comparison of this no-adverse-effect level for BPA of 100 micrograms/L, which was deemed protective of the structure and function of aquatic ecosystems, with typically measured values in surface waters of 0.001 to 1.0 micrograms/L indicates that aquatic ecosystems are unlikely to be adversely impacted by BPA (Staples et al, 2002).

The data in the validated studies and reviews described above, combined with current scientific understanding of BPA toxicity, indicate that the current manufacturing and use patterns of BPA pose virtually no risk to the environment.