UCI News

UCI’s Shahir Masri is co-first author of study showing how chemical intolerances develop

October 31, 2021
UCI’s Shahir Masri is co-first author of study showing how chemical intolerances develop

Shahir Masri, Sc.D., a research specialist in air pollution exposure assessment and epidemiology in UCI’s Program in Public Health, is co-first author of a study that demonstrates evidence of the mechanism for how and why people develop unexplained intolerances to chemicals, foods and drugs. Findings are published online in the journal Environmental Sciences Europe. Although intolerances to certain chemicals affect 15 to 30 percent of the U.S. population, the causes have not been well understood. However, more recently, researchers have described a two-step process of “toxicant-induced loss of tolerance” that links certain groups of chemicals to the onset of intolerance. The “initiation exposure event” involves either a single major exposure incident or repeated low-level encounters with chemicals such as pesticides and smoke, as well as chemicals found in newly renovated buildings and moldy environments. “Triggering” is the second stage, when individuals experience debilitating symptoms, including fatigue, headache, weakness and rash, when exposed not only to the chemicals that initiated their illness, but also to unrelated foods and drugs at levels that never bothered them before. “We established evidence of this previously understudied disease process,” Masri said. “Our insights will help public health scientists, physicians and policymakers better understand how to minimize harmful exposures and prevent future disease.” Other research team members were co-first author Dr. Claudia S. Miller and Raymond F. Palmer, Ph.D., of The University of Texas Health Science Center at San Antonio; and Nicholas Ashford, Ph.D., of the Massachusetts Institute of Technology.