“A Weight of Evidence
Approach to the Aquatic Hazard Assessment of Bisphenol
Bisphenol A Unlikely to Cause Adverse Effects in the
November 7, 2002
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.
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
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
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.
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
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.