Exposure to polycyclic aromatic hydrocarbons doubles risk of developing rheumatoid arthritis | Research

Exposure to polycyclic aromatic hydrocarbons (PAHs) formed during combustion can greatly increase the risk of developing rheumatoid arthritis (RA), whether you smoke or not. The authors said their findings supported and expanded the limited evidence for a relationship between PAH and rheumatoid arthritis.

PAHs are a class of ubiquitous chemicals formed when burning coal, oil, gas, wood, or from grilling meat. Cigarettes are also known sources of he PAHs.

This cross-sectional study aimed to explore the association between PAH and rheumatoid arthritis prevalence in smokers and nonsmokers while controlling for important confounding factors such as age, sex and BMI. Using data collected from 2007 to 2016 by the U.S. National Health and Nutrition Survey, we included over 21,000 adult participants, of whom 1,418 had rheumatoid arthritis.

Individual toxicants such as phthalates, plasticizer metabolites, volatile organic compounds (VOCs), and PAHs were evaluated for their association with RA. A physical burden score was established for each participant via blood and urine samples, providing a measure of exposure to these chemicals via the resulting metabolites.

People in the highest and lowest quartiles of PAH body burden were more than twice as likely to develop rheumatoid arthritis. After adjusting for confounders, only one PAH, 1-Hydroxynaphthalene, was associated with an increased chance of developing rheumatoid arthritis. In contrast, phthalates, plasticizers, and VOC metabolites were not associated with RA in fully adjusted models.

The researchers also analyzed whether PAH body burden mediates the relationship between smoking and rheumatoid arthritis. They found that smoking was associated with RA, and, like PAH body burden, PAH body burden was associated with RA even after adjusting for smoking. From this, the authors calculated that PAH body burden mediates nearly 90% of the overall effect of smoking on RA. PAH body burden was also significantly associated with RA in nonsmokers, but significance was not obtained in fully adjusted models.

The authors note that, to their knowledge, this study is the first to demonstrate that PAH not only underlies most of the relationship between smoking and rheumatoid arthritis, but also independently contributes to rheumatoid arthritis. said.

“This study supports and extends the available evidence that environmental PAHs are associated with the prevalence of rheumatoid arthritis in the US population, regardless of smoking status,” the authors write. ing.

Roy HarrisonA professor of environmental health at the University of Birmingham said the study was “conducted cautiously” but that it was important not to “overinterpret” the results. “The results show several positive and statistically significant positive associations between self-reported rheumatoid arthritis and several PAH metabolites measured in urine,” he said. added. “No such association was found for phthalate plasticizers or toluene.”

Harrison added that limitations of the study include the inability to objectively determine disease or diagnosis and small effect sizes for individual metabolites. “My interpretation is that this study supports the possibility that exposure to combustion-related pollutants may contribute to rheumatoid arthritis.”

“Even if this relationship is indeed causal, there can be no certainty that PAH is the cause,” explains Harrison. “However, the results suggest that exposures in the top quartile lead to twice his risk of disease compared to exposures in the bottom quartile, which is important from a public health perspective. is.”