The fall meeting of the North Carolina Society of Toxicology (NCSOT) featured talks on populations that are especially sensitive to toxicants. The program, organized by the NCSOT Executive Council, was held on the U.S. Environmental Protection Agency (EPA) campus Oct. 15 and featured speakers, a poster session, and awards (see sidebar).

Planned in conjunction with the Association for Inhalation Toxicology meeting, which was took place in Durham in the following days, the NCSOT event attracted nearly 200 registered attendees. “It was quite a large crowd for a regional meeting,” said NCSOT Vice President Erin Pias Hines, Ph.D, who works for EPA.

Hines is a biologist with the EPA National Center for Environmental Assessment. (Photo courtesy of Steve McCaw)

Epigenetic surprises

“Sometimes this [epigenetic] reprogramming is absolutely silent,” said Walker, explaining that transcription was not altered after chemical exposure until certain health challenges in later life. (Photo courtesy of Steve McCaw)

Keynote speaker Cheryl Lyn Walker, Ph.D., from Baylor College of Medicine, discussed intriguing findings in her studies of endocrine-disrupting chemicals and epigenetic changes, which are heritable changes to DNA that affect its function without changing the underlying genetic sequence.

A study of developmental exposure to an endocrine-disrupting chemical in mice yielded surprising findings, as yet unpublished. “We may see no effect until later life challenges,” she said. Not until the mice experienced a health stress in adulthood, such as a high fat diet or hormonal changes, were changes observed in transcription of the affected genes.

Walker thanked the NIEHS TaRGET II Consortium for funding some of this research.

Bananas, asthma, and pesticides

Jane Hoppin, Sc.D., from North Carolina State University, discussed the Infantes Y Salud Ambiental study, which involves a group of women and children who live and work on banana plantations in Costa Rica.

More than 27 active ingredients are used to protect banana plants and their fruit through growth, harvest, and storage, according to Hoppin. “About 2 million kilograms of pesticides are used each year, in an area of about 40,000 hectares,” she said.

Using ingenuity and advanced methods to address the complex exposures, poverty, and other challenges, Hoppin and her colleagues are finding links between asthma diagnoses and certain pesticide exposures.

She described similarities with data from the NIEHS-funded Agricultural Health Study. “What we saw was that the association of pesticides [with asthma] was stronger among people with allergies,” she said.

Hoppin, center, listened to a comment from Mike Hughes, Ph.D., also from EPA, during one of the animated discussion times following a presentation. (Photo courtesy of Steve MCaw)

Native Americans and lung disease

Matthew Campen, Ph.D., from the University of New Mexico, told a story of research that has not yet yielded the answers he sought, although he is uncovering important links along the way.

Navajo Nation and Laguna Pueblo lands hold abandoned gold, uranium, and vanadium mines, often located near residences. Campen and his colleagues suspected that disparities in an irreversible condition called interstitial lung disease (ILD) would be related to mining activities and associated dust. When the mining ceased, they expected to see a decrease in the unequal distribution of ILD. They did not.

Campen said his team did find links between lung inflammation and living near uranium mines. (Photo courtesy of Steve McCaw)

Metals in mining debris oxidize when released from underground, forming nanoparticulates. Dust from one site, called Claim 28, caused greater inflammation and toxicity in cells than background particles did. However, that site was downwind from nearby homes.

So Campen’s team looked for other explanations of ILD disparities and discovered that the most inflammatory conditions occurred during weather inversions. “Woodsmoke [containing ultrafine particles and other toxicants] gets socked in on inversion days,” he said.

Kodavanti’s research suggests that experiencing psychosocial stress may increase susceptibility to the harmful effects of ozone in air pollution, due to the influence of stress hormones. (Photo courtesy of Steve McCaw)

Overlooked stress hormones and ozone

Urmila Kodavanti, Ph.D., from EPA, discussed the neuroendocrine system, which regulates a wide range of stress responses. “Yet it is not systematically integrated into air pollution health effects studies,” she pointed out.

For example, Kodavanti said that ozone induces hyperglycemia and glucose intolerance. She observed that the liver produced more glucose even as that glucose-mediated insulin secretion stopped. She suggested this is likely mediated by stress hormones.

In other studies, Kodavanti said that mothers and children experiencing psychosocial stress have increased susceptibility to asthma and inflammatory responses. Thus, they may be more sensitive to air pollution exposures.