Building on his prior interview discussion regarding environmental drivers of atopic dermatitis, Matthew Zirwas, MD, touched on emerging research exploring the role of toluene diisocyanate (TDI), an industrial chemical he believes may help explain the increasing rates of eczema observed over the past several decades.1
Key Takeaways:
- Emerging research suggests the environmental chemical toluene diisocyanate (TDI) may contribute to the rising prevalence of atopic dermatitis.
- Zirwas noted that mechanistic and epidemiologic evidence has made TDI a compelling hypothesis for explaining several long-observed trends in eczema.
- If future research confirms these findings, reducing certain environmental exposures could become an additional strategy for counseling patients and families about atopic dermatitis.
Speaking with HCPLive following his presentation at the 2026 SDPA Summer Dermatology Conference, Zirwas pointed to research led by Ian Miles, MD, at the National Institutes of Health that used spatial data analysis to compare the geographic distribution of environmental chemicals with rates of atopic dermatitis. According to Zirwas, TDI consistently emerged as the environmental exposure most strongly associated with eczema prevalence across multiple statistical analyses.
He noted that the proposed association is supported not only by epidemiologic findings but also by mechanistic evidence. Zirwas described TDI as being already recognized by the US Food and Drug Administration (FDA) to be a substance capable of inducing eczema in animal models. He also noted its common use in preclinical research to determine atopic dermatitis before evaluating investigational drugs. He pointed to this biological evidence, combined with the geographic correlations, as making TDI a compelling area for continued investigation.
According to Zirwas, timing and distribution of TDI exposure also align with longstanding epidemiologic observations, including the noted increase in atopic dermatitis beginning in the 1970s and the higher prevalence of disease in urban environments.1,2 While he acknowledged that research in this area is ongoing, he described the hypothesis as one that brings together several previously unexplained patterns in atopic dermatitis.