High uranium exposure linked to SLE patients living near former plant

WASHINGTON — High uranium exposure was associated with systemic lupus erythematosus among patients who resided near a former refinery when compared with controls, according to research presented at the American College of Rheumatology Annual Meeting.

Researchers used data from the Fernald Community Cohort (FCC), a study comprised of 9,782 voluntarily enrolled adults and children who lived within 5 miles of a uranium ore processing facility in Fernald, Ohio. Participants, which excluded plant workers, were followed from 1990 to 2008.

ICD9 codes associated with lupus (710.0 and 695.4) and a medication code search for hydroxychloroquine were used to identify potential systemic lupus erythematosus (SLE) patients. Potential patients’ sera were screened for autoantibodies, and American College of Rheumatology classification criteria and medical record documentation were used for confirmation. For every SLE case, four age-, race- and sex-matched controls were selected. A dosimetery model calculated cumulative uranium exposure. Preliminary analysis with rheumatoid arthritis (RA) was used for comparison.

“Lupus patients have a reputation for being sensitive to sunlight and radiation, in addition to literature hinting that miners may be at increased risk for developing lupus,” researcher Pai-Yue Lu, MD, clinical fellow at Cincinnati Children’s Hospital Medical Center, said in explaining the study rationale.

There were 4,187 people with low uranium exposure, 1,273 with moderate exposure and 2,756 with high exposure in the FCC. SLE was confirmed in 25 patients — 21 with an ICD9 code of 710.0, two with ICD9 code of 695.4 and two who were prescribed hydroxychloroquine. Five patients were in the low uranium exposure group, eight were in the moderate exposure group and 12 were in the high exposure group. SLE was associated with high exposure when analyzed by logistic regression modeling (OR=4.81; 95% CI, 1.38-16.75); no association was found, however, between SLE and low or moderate uranium exposure. SLE increased fivefold over the expected prevalence in the overall FCC, while RA occurred at expected prevalence.

“Lupus has approximately four times the odds of occurring with high [uranium] exposure compared with no exposure,” Lu said. “We did not find other exposures, such as smoking and alcohol, to be related to lupus in our study.”

Among the explanations for the relationship are “the estrogen effects of uranium, somatic mutation from ionizing radiation or effects of some other unidentified accompanying exposure,” the researchers said.

“By understanding this [lupus-uranium] relationship better,” Lu said, “we can gain more information about what types of environmental factors contribute to disease development and the mechanisms in which they work.”

For more information:

Lu P-Y. P1606: Identifying a Link Between Uranium Exposure and Systemic Lupus Erythematosus in a Community Living near a Uranium Plant. Presented at: American College of Rheumatology 2012 Annual Meeting; Nov. 10-14, Washington.