October’s column is focused on the screening risk assessments of three different RTS exposures conducted by Canada’s Departments of Environment and Health. The assessments of inhalation and of dermal exposure during sealant application found little reason for human health concern. The assessment of possible exposure to RTS-containing dust in residences near sealed parking lots included calculation of a value called a “Margin of Exposure” (MOE). For the assessment, “lifetime adjusted MOE” values were calculated, with the conclusion:
The resulting MOEs for each age group were then weighted according to their time length; the resulting Lifetime Adjusted MOE is 15 500. (Draft Screening Assessment, p. 58)
Higher MOE values mean that the risk is lower. There’s an explanation on the US National Library of Medicine web site. The table on that web site indicates a one time MOE for eating bacon of 10,000 and a one time MOE for drinking treated tap water of 20,000. This shows that a lifetime MOE value of 15,500 indicates that there is little reason for concern. Indeed. government health agencies around the world use MOE values greater than 10,000 as a precautionary indicator that there should be little concern for public health.
Read the Pavement Magazine column here.