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Comprehensive Japanese Risk Assessment on Bisphenol A Confirms No Risk to Human Health or Environment

March 20, 2006

Summary

A comprehensive risk assessment recently completed by the Japanese government has found that bisphenol A is not a risk to human health or the environment. The assessment was conducted by scientists at the National Institute of Advanced Industrial Science and Technology, which is a public research organization affiliated with the Japanese Ministry of Economy, Trade and Industry.

The overall conclusion of the assessment is that current exposure levels of bisphenol A do not pose unacceptable risks to human health or to the environment. Based on this assessment, it was further concluded that it is unnecessary to prohibit or restrict the use of bisphenol A. The conclusions from this assessment are consistent with the views of government bodies worldwide, none of which have banned or restricted the use of bisphenol A.

Who Conducted the Assessment and What Did They Do?

A comprehensive human health and environmental risk assessment was conducted by scientists at the Research Center for Chemical Risk Management (CRM) of the National Institute of Advanced Industrial Science and Technology (AIST). Affiliated with the Japanese Ministry of Economy, Trade and Industry, AIST is Japan's largest public research organization and CRM has conducted extensive research on the development and application of risk assessment methodology.

In this assessment, a large amount of data on the exposure and hazards of bisphenol A were reviewed and analyzed. Risks to human health and the environment were characterized by a series of conventional and more sophisticated approaches. The complete risk assessment was published in November 2005 in Japanese language and a detailed English language summary is now available on the AIST website. (1)

What Were the Results of the Human Health Risk Assessment?

The overall conclusion of the human health risk assessment is that "current exposure levels of BPA will not pose any unacceptable risk to human health." This conclusion is based on a comprehensive review of the toxicological profile of bisphenol A combined with estimates of human exposure to bisphenol A. The exposure estimates were derived from two different methodologies.

Key aspects of the human health assessment include:

• A No-Observed-Adverse-Effect-Level (NOAEL) or Benchmark Dose Lower Limit (BMDL) was established for three key toxicological endpoints. All were in the range of 5-50 milligrams/kg-bodyweight/day.
• For reproductive toxicity, a NOAEL of 50 milligrams/kg-bodyweight/day was established based on a comprehensive study that examined the effects of bisphenol A over the course of four generations of laboratory animals. (2)
• Notably, findings from studies claiming reproductive effects at much lower doses were not considered to be robust in comparison to the consistent findings from studies reporting no low-dose effects.
• The most realistic estimates of human exposure to bisphenol A were derived from measurements of bisphenol A in human urine(3). From these studies, average exposure was in the range of 28-49 nanograms/kg-bodyweight/day for adult males and 34-59 nanograms/kg-bodyweight/day for adult females.
• Comparison of the most realistic exposure estimates with the NOAELs and BMDL led to Margins of Exposure (MOE) in the range of 85,000-1,800,000. The MOEs represent the gap between estimated exposure and the level above which effects might be seen and are all sufficiently large to support the conclusion that bisphenol A is not a risk to human health. The MOEs were also sufficiently large (greater than 1,000 in every case) for adults and children when exposure estimates from a more conservative, worst-case method were used for the comparison.

What Were the Results of the Environmental Assessment?

The overall conclusion of the environmental risk assessment is that "current exposure levels of BPA will not pose unacceptable risks to the local populations of aquatic life, particularly fish." This conclusion is based on a very large database of measured levels of bisphenol A in the aquatic environment in Japan, which were evaluated with three assessment methodologies.

Key aspects of the environmental assessment include:

• Bisphenol A is readily biodegradable in the aquatic environment.
• Nearly 4000 measurements of bisphenol A levels in fresh surface water, covering 1,120 areas in 752 rivers, were evaluated. The average concentrations were 0.005 micrograms/liter or less (= 5 parts per trillion) in approximately 30% of the areas and 1 microgram/liter or less (= 1 part per billion) in 99% of the areas.
• For the vast majority of measured bisphenol A levels in fresh surface water (>98%), no effects on susceptible aquatic organisms are expected. These levels are more than ten times lower than the lowest No-Observed-Effect-Concentration of 16 micrograms/liter measured in any of the many toxicity studies on aquatic organisms.
• For the few areas with higher bisphenol A levels, two additional assessment methods were used to test for unacceptable risks. A more sophisticated assessment of the growth rates of local populations of five fish species revealed that, even at the highest measured concentrations, the conservatively estimated growth rates of the fish species would not be adversely impacted. This conclusion was tested by field observations of the presence and condition of fish species in areas with the highest bisphenol A levels; the field observations found no indication of adverse impacts on local fish populations.

Conclusions Consistent With Other Recent Assessments

The conclusions from this risk assessment are consistent with the conclusions from other recent assessments and statements made by regulatory bodies worldwide. In every case, these assessments support the view that bisphenol A is not a risk to human health or the environment.

Recent government-sponsored risk assessments continue to support the safety of products made from bisphenol A, and bisphenol A has not been banned or restricted anywhere in the world. In addition to this new Japanese assessment, other recent assessments include:

• A European Commission sponsored risk assessment on both human health and the environment. , (4, 5)
• An assessment of bisphenol A in products that contact food conducted by the European Commission's Scientific Committee on Food. (6)
  

1 An abstract and detailed summary of the bisphenol A risk assessment are available at http://unit.aist.go.jp/riss/crm/mainmenu/e_1-10.html.

2 "Three-Generation Reproductive Toxicity Study of Dietary Bisphenol A in CD Sprague-Dawley Rats", R. W. Tyl, C. B. Myers, M. C. Marr, et al., Toxicol. Sci. (2002) 68 (1):121-146.

3 For a discussion on bisphenol A biomonitoring, see our May 2005 article titled Biomonitoring Studies Confirm Human Exposure to Bisphenol A is Very Low.

4 Read a PDF-formatted summary of the European risk assessment. You can also read a PDF version of the full risk assessment document.

5 Read our discussion of the European Commission's Scientific Committee on Toxicity, Ecotoxicity and the Environment review of the European risk assessment, and both http://ec.europa.eu/health/ph_risk/committees/sct/documents/out159_en.pdf and http://ec.europa.eu/health/ph_risk/committees/sct/documents/out156_en.pdf for the complete CSTEE assessments on the environment and human health.

6 Read our discussion of the European Commission's Scientific Committee on Food assessment of bisphenol A, and see http://europa.eu.int/comm/food/fs/sc/scf/out128_en.pdf for the complete assessment.