Friday, November 13, 2015

Asarco arsenic and cancer

NOVEMBER 13, 2015
How we know the smelter was harmful

Exposed workers provided most important clues
Smelter workers were two to eight times more likely to die of lung cancer than average
Arsenic also linked to other types of cancer

Contributing writer

Some have questioned how we know that particular people were harmed by the Asarco smelter ("Toxic legacy surprises Tacoma newcomers," 11-7). I'll explain.
We don't make decisions about the harms of the environmental contaminants based on individual stories. Rather, we use epidemiologic studies to try to determine whether or not exposure to environmental contaminants causes harm.
These issues can be very difficult to study and can take decades to sort out. But often highly exposed workers provide clues to health effects that might be harder to study in the community. Tacoma smelter workers are famous in epidemiologic circles because studies of their mortality have provided convincing evidence that exposure to arsenic causes lung cancer.
Here is what the research says about Tacoma: Men who worked at the smelter were between two and eight times (depending on their level of exposure to arsenic) more likely to die of lung cancer in comparison to males in Washington state as a whole.

Both industry-funded and independent studies of Tacoma smelter workers have come to the same conclusion: There is an increased risk of lung cancer death among Tacoma smelter workers. Asarco admitted as much to the Occupational Safety and Heath Administration (OSHA) in 1975.
Arsenic not only causes lung cancer but is also linked to cancer of the skin, bladder, liver and kidney, and a host of non-cancer health effects.

In the 1970s, both the Washington State Health Department and Asarco measured arsenic concentrations in children's urine in Ruston that were quite high, even compared to children living in other smelting communities.
Elevated urinary arsenic has been linked to health and developmental problems in children in international studies. Unfortunately there have been no studies of children in Tacoma that have started with a measurement of their arsenic exposure and then followed them over time to see if their health was affected. Local researchers wanted to do such studies in the 1970s and 1980s but could not get them funded.

However, a well-designed study of health effects among community residents found that women who lived near the smelter for 20-plus years had a small increased risk of lung cancer. The authors themselves said this "excess risk may be expected" since arsenic in the community's air often exceeded OSHA's occupational standard.
Arsenic was only one toxic agent emitted by the smelter. It also emitted very large quantities of sulfur dioxide, lead and other heavy metals. Sulfur dioxide air pollution is associated with adverse respiratory health effects and premature mortality.

When the smelter was still operating and pumping out massive quantities of sulfur dioxide, there is no doubt that respiratory effects occurred in nearby residents, particularly among asthmatics and other sensitive populations.
North Enders complained constantly of choking and coughing and other respiratory symptoms, but health and regulatory authorities had little sway over the company. Asarco, working with the Chamber of Commerce, even helped scuttle a health study that the City of Tacoma wanted to conduct about this problem in the early 1960s.
There have been very few studies of lead levels in children living near the smelter. But in the early 1970s, some Ruston children were found to have elevated blood lead, with some young children living close to the smelter exhibiting levels dangerously high by today's standards – levels linked with damage to the developing brain.
It is not clear the extent to which lead from gasoline (leaded gasoline was still in use), lead from smelter emissions or lead in paint caused these elevated blood lead levels, but we do know that the smelter was a significant source of environmental lead.
In addition to human health harm, many studies (a large number done by University of Washington researchers) have documented the smelter's impact on water quality in the Puget Sound region, soils and sediments, contribution to acid rain and acidification of Cascade Lakes (while it was operating), and many other ecosystem impacts.
Once toxic metals are in the environment, they are there to stay unless cleaned up. Tacoma is an object lesson in largely unchecked and unregulated industry pollution. Unfortunately, the primary smelting industry has increasingly moved to developing countries where a similar story of environmental and public health harm is unfolding.
Marianne Sullivan, doctor of public health, is an assistant professor of public health at William Paterson University in New Jersey. Her 2014 book, "Tainted Earth: Smelters, Public Health and the Environment," covers smelters and their public ...

No comments: