What's New

“A Weight of Evidence Approach to the Aquatic Hazard Assessment of Bisphenol A” concludes:
Bisphenol A Unlikely to Cause Adverse Effects in the Aquatic Environment

November 7, 2002

Summary

A comprehensive weight-of-evidence assessment of the ecologically relevant endpoints of survival, growth and development, and reproduction, recently published in the Human and Ecological Risk Assessment journal¹, concludes that Bisphenol A (BPA) is unlikely to cause adverse effects on aquatic populations or ecosystems.

Many studies have been conducted to determine the potential effects of BPA on the survival, growth and development, and reproduction of aquatic organisms. The recently published weight-of-evidence assessment of these endpoints concluded that adverse effects occur only at BPA concentrations of 160 micrograms/liter and above. This is significantly higher than typical surface water concentrations of BPA in the range of 0.001 to 0.5 micrograms/liter, and, therefore, BPA is unlikely to cause adverse effects on aquatic populations or ecosystems.

********************

Bisphenol A is Readily Biodegradable and Does Not Bioaccumulate

Bisphenol A (BPA) is used primarily as an intermediate to make polycarbonate plastic and epoxy resins. Although the vast majority of BPA is converted at manufacturing sites into these and other products, low-level releases of BPA to the environment are possible, with low-level releases to surface water believed to be the principal route of environmental exposure.

The fate of BPA in the aquatic environment has been well characterized by laboratory studies using accepted international guidelines as well as real-world monitoring studies. These studies consistently demonstrate that BPA is rapidly biodegraded and removed from the aquatic environment. In addition, BPA does not bioaccumulate in aquatic organisms to any appreciable extent.

Although BPA rapidly biodegrades, the development of increasingly sensitive analytical methods now allows detection of BPA at levels less than 1 part per billion (1 microgram/liter). These advances have led to a number of published reports that measured very low concentrations of BPA in surface water. Median reported concentrations of BPA in streams and rivers are approximately 0.01-0.02 micrograms/liter in Japan and Europe. In the United States, median values in the range of 0.1-0.5 micrograms/liter have been reported, but these values primarily reflect limitations in the analytical methodology used. Many samples in each region contained no BPA at the limit of detection and virtually all samples tested contain less than 1 microgram/liter.

Weight-of-Evidence Assessment Shows Adverse Environmental Effects Unlikely

The characteristics and typical concentrations of BPA in surface water do not raise concerns that BPA might cause environmental effects. Nevertheless, a considerable amount of research has been conducted on the potential effects of BPA in the environment, in particular on aquatic organisms. As described in a recent peer-reviewed publication¹ in the Human and Ecological Risk Assessment journal, the results of this research allow an assessment of the potential risks to populations of aquatic organisms and ecosystems.

The publication both critically reviews the available literature on the aquatic toxicity of BPA and conducts a weight-of-evidence hazard assessment based on the large body of valid data identified in the review. All available studies were critically reviewed for technical quality and suitability for use in risk assessments following the criteria and procedures outlined in a European Commission Technical Guidance Document². Consideration was also given to whether the studies were conducted under internationally accepted principles of Good Laboratory Practice.

Particular emphasis was placed on studies that focused on ecologically relevant endpoints of survival, growth and development, and reproductive success. The review yielded approximately 70 NOECs (No Observed Effect Concentrations) and LOECs (Lowest Observed Effect Concentrations) covering these endpoints in various aquatic species. The LOECs range from 160 to 11,000 micrograms/liter and the NOECs range from 16 to 3,640 micrograms/liter. Regarding these endpoints, the review concluded that:

• BPA has a minimal effect on the survival of aquatic organisms at elevated dose levels;
   
• Exposure to BPA does not reduce growth of vertebrates, invertebrates and algae at concentrations below about 400 micrograms/liter; and
   
• Effects on reproductive success in fish, amphibians, invertebrates and algae have been observed only at concentrations of 160 micrograms/liter and higher.

Across the entire dataset, adverse effects on ecologically relevant endpoints were observed only at concentrations of 160 micrograms/liter and above.

Based on the full range of data, a weight-of-evidence hazard assessment was conducted using established principles.³ The abundant NOEC and LOEC dataset indicates that aquatic effects on survival, growth and development, and reproduction are not likely to occur at BPA concentrations below 160 micrograms/liter, based on repeated measurements of these ecologically relevant endpoints. This conclusion is comparable to that derived earlier using a statistical extrapolation procedure to estimate no-effect concentrations that are protective of aquatic populations and ecosystems. The statistical approach estimated that effects on populations and ecosystems are not likely to occur below about 100 micrograms/liter.⁴

When the 160 micrograms/liter concentration, below which effects are unlikely to occur, is compared with typical surface water concentrations of BPA in the range of 0.001 to 0.5 micrograms/liter, it is clear that BPA is unlikely to cause adverse effects on aquatic populations or ecosystems.

For more details and literature citations on the environmental fate and effects of BPA, see the Environment section of this website at http://www.bisphenol-a.org/esafety/index.html.

References

¹“A Weight of Evidence Approach to the Aquatic Hazard Assessment of Bisphenol A”, C. A. Staples, K. Woodburn, N. Caspers, A. T. Hall, and G. M. Klecka, Hum. Ecol. Risk Assess., 2002, vol. 8, no. 5, pages 1083-1105.

² Technical Guidance Document in Support of Commission Directive 93/67/EEC on Risk Assessment for New Notified Substances and Commission Regulation (EC) No. 1488/94 on Risk Assessment for Existing Substances. Part II. 1996 (Revised 2003). Available on the Internet at http://ecb.jrc.it/Documents/...

³ “A critical evaluation of safety (uncertainty) factors for ecological risk assessment”, P. M. Chapman, A. Fairbrother, and D. Brown, Environ. Toxicol. Chem., 1998, vol. 17, pages 99-108.

⁴ “Regional-Scale Risk Assessment of Bisphenol A in Surface Waters using Refined Predicted No Effect Concentrations”, C. A. Staples, A. T. Hall, K. B. Woodburn, and N. Caspers, 2001, Society of Environmental Toxicology and Chemistry, 11th Annual Meeting, Madrid, Spain.