Lupus cluster at oilfield points finger at pollution
Aria Pearson
11 May 2007
NewScientist.com news service
An alarmingly high number of people living in houses built on top of a disused oilfield in New Mexico have been diagnosed with the autoimmune disease lupus. It is the latest in a growing number of lupus clusters near polluted areas, and points towards the environmental triggers for this complex disease.
When someone has lupus their immune system turns against them, attacking their own tissues, which can lead to joint pain, organ failure and even death. In the US, it is much more common in women and minority groups, especially African Americans. The Centers for Disease Control and Prevention in Atlanta, Georgia, estimates that the incidence of the disease has tripled in the past 40 years.
Pollutants seem to be the cause of lupus in people on a housing development in Hobbs, New Mexico, built in 1976 on land that was an active oilfield until the late 1960s. The community noticed an unusually high rate of lupus and contacted James Dahlgren, an environmental toxicologist at the University of California, Los Angeles.
Dahlgren and his colleagues compared the prevalence of lupus in the Hobbs development to its prevalence in the general population and found that the rate of lupus in the Hobbs population was 30 to 99 times higher than estimates for the general population. “The rate is astronomically high,” says Dahlgren. “It’s a true cluster.” All the cases in Hobbs occurred in several blocks of houses built on top of a waste pit.
The researchers found that levels of mercury and a petroleum hydrocarbon called pristane were higher in the Hobbs community, especially near the waste pit, than in a control neighbourhood about 200 kilometres away. Both of these pollutants are known to cause lupus in animals. Pristane was also found in greater amounts in the blood of people living in the exposed area. The study did not test for levels of mercury in their blood (Environmental Health, DOI: 0.1186/1476-069X-6-8).
Previous studies have shown a connection between mercury and lupus in people, but this is a first for pristane, an environmental pollutant that also occurs naturally in mineral oil and shark oil.
Other clusters of lupus have been documented in people exposed to industrial emissions, solvents and pesticides for a long time. A study under way in Buffalo, New York, has recorded 92 cases of lupus in an area near a lead-smelting plant that closed in the 1980s. Lead, mercury and arsenic are among the pollutants found at the site, says Edith Williams, a project coordinator for the study.
To pin down the pollutants that cause lupus, we need to know how genes that predispose someone to lupus interact with the environment, says Dahlgren.
Many mutations have been linked to lupus, especially those in immune system genes. Gary Gilkeson of the Medical University of South Carolina in Charleston says there are probably 40 to 50 different genes involved, many of which could affect how a person deals with pollutants. “Once the genes are figured out, it will be easier to track down the environmental factors,” he says.