A panel of external scientific experts reviewed the findings of the CLARITY-BPA Core Study April 26 at NIEHS and agreed that for this first of the two CLARITY-BPA components, there were minimal toxic effects of bisphenol A (BPA) exposure in rats for the range of doses studied.

Walker coordinates the collaboration among FDA, NIEHS, and CLARITY-BPA grantees. (Photo courtesy of Steve McCaw)

CLARITY BPA stands for Consortium Linking Academic and Regulatory Insights on BPA Toxicity. The study is a research collaboration among NIEHS, the National Toxicology Program (NTP), and the Food and Drug Administration (FDA).

The experts recommended revisions to several specific interpretations of the study findings, which will be considered by NTP and FDA staff as they finalize the core study report.

“The panel conducted a thorough review of the CLARITY-BPA Core Study and provided many insightful comments,” said Nigel Walker, Ph.D., chief of the NTP Toxicology Branch.

“They appreciated the NTP approach of examining the totality of the evidence, rather than just statistical analyses, and acknowledged that there will be other data streams, like the grantee data, that will help interpret the health effects of BPA in this study.”

“They supported the NTP approach of examining the totality of the information, including health effects at different doses and in different tissues, statistical tests, and whether observations could be explained by normal biological variability, rather than BPA exposure.”

Panelist Tracie Bunton, D.V.M., Ph.D., center, founder of Eicarte LLC, listened to the study results, along with, from left, NCTR scientists Robert Felton, Luisa Camacho, Ph.D., and Greg Olson, D.V.M., Ph.D. (Photo courtesy of Steve McCaw)

NIEHS and FDA convened CLARITY-BPA to study the full range of potential health effects from exposure to BPA in rats and to provide data that could be used for regulatory decisions. CLARITY-BPA united standard research practices used by regulators, called federal guideline studies, with innovative research conducted at universities through grants from NIEHS (see sidebar).

Endocrine disruption not yet clear

One purpose of CLARITY-BPA was to assess whether federal guideline studies are sensitive enough to detect health effects from low-dose, endocrine-disrupting chemicals. NTP Senior Scientist John Bucher, Ph.D., said that question can only be answered through comparison of the core study with the grantee studies.

“This study answers a more limited question, not whether BPA is hormonally active,” said panel member Michael Conner, D.V.M., from Global Blood Therapeutics, Inc.

NTP Associate Director Brian Berridge, D.V.M., Ph.D., right, and NCTR Director William Slikker, Ph.D., welcomed panelists and thanked them for their contributions. (Photo courtesy of Steve McCaw)

Grantee studies ongoing

The CLARITY-BPA grantees are currently publishing findings in peer-reviewed journals and will make their data public in August 2018.

Their studies used control animals, BPA-exposed animals, and BPA-exposed tissues from animals handled identically to those in the core study. This ensured that animals used in both parts of the study were raised in the same conditions and exposed to the same doses of BPA.

The samples were blinded, meaning the university researchers did not know if the animals and tissues they received were dosed with BPA, and if so, by how much.

The final CLARITY-BPA conclusions will integrate the core study and the grantee studies. The conclusions are expected in 2019.