Dec. 13 2016

An Environmental Health Scientist’s Mind for Metals

Ana Navas-Acien looks at how arsenic, lead, and cadmium raise risk for chronic disease, with an eye to preventing and mitigating exposures

Ana Navas-Acien, who joined the Mailman School as professor of Environmental Health Sciences this summer, researches how environmental exposures affect chronic disease, and she’s particularly drawn to understanding exposure to various metals and their impact on cardiovascular disease, diabetes, and cancer rates.

Arsenic

While it’s common knowledge that arsenic, a metaloid element, is extremely bad for human health at high levels, Navas-Acien wanted to learn if and how low and moderate levels of arsenic exposure could affect disease. As part of a study of Native American communities in Arizona, Oklahoma, North Dakota, and South Dakota while at Johns Hopkins University, she discovered that arsenic did raise the risk of chronic disease, even at levels at or below those allowed by the Environmental Protection Agency.

“In these and other rural communities in the U.S., arsenic occurs naturally in groundwater, and it’s a major challenge,” she says. These communities, like so many across the country, depend on well water, which is not regulated. “There’s no requirement to test well water, so families are left on their own, without any protection.”

It’s one of the reasons why Navas-Acien was excited to come to Mailman: The Columbia SuperFund Research Center, led by Joseph Graziano, professor of Environmental Health Sciences, has a dedicated team working on well water safety, both by learning about the risks and designing interventions to help communities. Right now, she is collaborating with community organizations in South Dakota and Mailman School of Public Health alumna Christine George (PhD, 2002) studying the effectiveness of interventions to prevent arsenic exposure by providing and installing water filters and designing programs to encourage their use and upkeep.

Lead

The harmful, long-term neurological effects of lead exposure on children are well-documented. But the scientific community understands a lot less about the effects that lead exposure can have on adults, particularly when it comes to cardiovascular disease.

But one important clue may be found in history: the rise and fall of leaded gasoline use corresponds to heart disease rates. “It’s remarkable: the cardiovascular disease epidemic in the United States parallels the lead epidemic,” says Navas-Acien.

Lead, unlike arsenic, stays in the human body for decades, and there’s no easy way to flush it out. The metal is drawn close to calcium in bones and results in continual exposures through the blood. Chelation, an oral version of which was developed by Graziano in 1978, can effectively remove metals including lead from the body, but not without potential drawbacks. As Navas-Acien points out, the therapy might also remove minerals the body needs. She is now working with Regina Santella, professor in Environmental Health Sciences, and other investigators on a large new clinical trial to better understand chelation, how effective it is to remove lead from the human body, and the potential benefit of this removal for cardiovascular health.

Cadmium

Cadmium, a metal found in the ground, is absorbed by root vegetables and leafy green plants like spinach and tobacco. The vast majority of problems related to cadmium exposures occur when it’s highly concentrated, as it is in cigarettes. Navas-Acien has found strong associations between cadmium exposure with heart disease and cancer. In future studies, she hopes to determine if the process of chelation could help mitigate the effects of cadmium.

While cadmium is found at harmfully high levels in cigarettes, it’s not one of the metals that Navas-Acien has discovered in e-cigarettes, which depend on a metal coil to heat the liquid inside. In an ongoing study, she seeks to learn if the coil releases harmful metals into the liquid and, ultimately, the smoke inhaled by e-cigarette users. In her early results, she’s found that the coils contain lead, nickel, chromium, tin, and zinc. 

No matter the metal, Navas-Acien has found the perfect fit in Environmental Health Sciences for her passions and sees how far-reaching her work can be: “If we have clean air, safe food, safe water, health will be much better.”