Mark Lafranconi is a Principal Toxicologist based in ERM’s Cincinnati, Ohio office. Mark has over 35 years of experience in the field of toxicology and risk assessment evaluating the health effects of consumer products, ingredients, and environmental chemicals. He has contributed risk assessments and read-across justifications to dozens of European REACH dossiers and US EPA Premanufacturing Notifications (PMNs) as well as European and US Food Contact Notifiations. He has more than 20 publications in peer reviewed journals and book chapters.
Mark is certified with the American Board of Toxicology, past president of the Ohio Valley Society of Toxicology and past chair of the Society of Toxicology Communications Committee.
A Path Forward for 1,4-Dioxane: Opportunity for Increasing Remediation Goals
1,4-Dioxane continues to be a significant contaminant at many remediation sites. In 2010 and 2013, USEPA updated the risk assessments for 1,4-dioxane under the Integrated Risk Information System (IRIS). The IRIS assessments resulted in a significant lowering of the remediation goals for 1,4-dioxane. Based on the available data at the time, USEPA used the default, and more conservative, linear model to assess the cancer risks from 1,4-dixoane exposure. This decision was controversial at the time and not universally accepted by risk assessors.
Since the latest IRIS assessment, additional information has been developed which supports a threshold mechanism of action over the default linear model used in the IRIS assessments. Research completed by others (Dourson et al. 2014, Dourson et al. 2017, Becker et al. 2017) provides strong evidence that the non-linear (threshold) model for estimating the cancer risk of 1,4-dioxane is more appropriate.
Re-opening the IRIS assessment for 1,4-dioxane is unlikely to occur given the lack of funding and current priorities of USEPA. This paper discusses a proposed approach that does not rely on IRIS to advocate for the application of the threshold cancer model in projecting risks from 1,4-dioxane in groundwater.