During the June 15-16 meeting of the National Toxicology Program (NTP) Board of Scientific Counselors,Scott Masten, Ph.D., head of the NTP Office of Nomination and Selection, briefed the board on the long-standing NTP open nomination process, the important role that exposure and hazard information play in priority setting, and the role of partner agencies. His presentation set the stage for the new research projects discussed later in the meeting.
Paul Howard, Ph.D., from the U.S. Food and Drug Administration (FDA) National Center for Toxicological Research, discussed the partnership between NTP and the center, which began with an interagency agreement in 1991 to support toxicological studies of mutual interest to NIEHS, NTP, and FDA. Howard highlighted reports from the nearly 40 substances that the agencies have supported, including dietary supplements, food-related products, bisphenol A (BPA), and nanomaterials.
Kelly Shipkowski, Ph.D., a postdoctoral fellow in the NTP Toxicology Branch, presented a proposal to study thallium compounds, which are used in the electronics industry and emitted as byproducts from smelting and other industrial processes.
The U.S. Environmental Protection Agency (EPA) nominated these compounds, because of potential widespread contamination in drinking water and soil. EPA requested that NTP conduct subchronic toxicity studies for establishing an oral reference dose. Shipkowski described a proposed multipronged approach. Board members suggested NTP use in vitro approaches to design optimal animal studies.
Synthetic turf, with a focus on crumb rubber
Abee Boyles, Ph.D., from the NTP Office of Health Assessment and Translation (OHAT), described NTP plans for studies on synthetic turf, with a focus on turf using crumb rubber infill. Synthetic turf is widely used in athletic fields and on playgrounds where children’s exposure to crumb rubber can occur by eating, skin contact, or inhalation. Crumb rubber is manufactured from shredded automotive tires and can release small amounts of hazardous substances under certain conditions.
The California Office of Environmental Health Hazard Assessment, who submitted one of the three nominations on this issue, requested that NTP conduct toxicological studies to better understand health impacts of substances contained in, or emitted by, turf. Board members and a public commenter acknowledged concern for potential health risks, and board members recommended that NTP characterize conditions under which exposures might occur, before launching toxicology studies.
The proposed NTP efforts to study the widely-used herbicide glyphosate were presented by NTP genetic toxicologist Stephanie Smith-Roe, Ph.D. She said that NTP published results in 1992 from short-term studies, in which no significant lesions were identified in rats and mice fed glyphosate. More recent studies and analyses show conflicting interpretations as to whether glyphosate presents a cancer risk for humans.
Smith-Roe described the current NTP thinking on studies that would advance understanding of the many formulations of glyphosate on the market. Such studies would include rapid screening and short term in vivo tests, to evaluate both cancer and noncancer-related endpoints.
NTP and clinical research
Kristina Thayer, Ph.D., NTP Deputy Division Director for Analysis and OHAT director, and Kristine Witt, Genetic Toxicology Group leader, teamed up to highlight NTP projects that use the NIEHS Clinical Research Unit (CRU). They described studies on the pharmacodynamics of, and exposure to, BPA and BPA alternatives, as well as a project aimed at improving characterization of exposure to personal care products. Witt discussed an ongoing study to evaluate the potential adverse health effects of black cohosh, an herbal supplement used by women.
Following the presentation, board members joined Shepherd Schurman, M.D., CRU associate medical director, for a tour.
(Robin Mackar is news director in the NIEHS Office of Communications and Public Liaison, and a frequent contributor to the Environmental Factor.)