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DEPARTMENT OF HEALTH 1,4-Dioxane in Privat e Wells - White Bear Area 8/24/2021 Gem lake and the Recent private,well sampling In Gem Lake has detected the cheinica! 1;4 dioxane above,th'e Minnesota Department of Nealth (MDH) drinking water guidance value' What is 1,4-dioxane? The main use of 1,4-dioxane was as a stabilizer for the chlorinated solvent 1,1,1-trichloroethane {often used for industrial purposes)..114-dioxane can also be an unintended contaminant in the production of certain products, including some. cleaners, detergents, adhesives, inks, automotive fluids, etc. Groundwater contaminated with 114-dioxane is largely caused by the historical use and disposal of chlorinated solvents. How can I be exposed to 1,4-dioxane? Drinking contaminated water is the primary way people are exposed. Minor sources of exposure are food prepared with contaminated water and:incidental ingestion and inhalation of water vapor during showering. Absorption through the skin is:a[so thought to be insignificant. MDH Health Risk Limits Minnesota Department of Health (MDH) uses Health Risk Limits (HRLs) to protect people's health from drinking water contaminants. The table below shows three HRL values for 1,4- dioxane set by MDH, for differing time frames and possible health endpoints they are based on. The 1,4-dioxane HRL of 1 part per billion (ppb) represents an amount of a contaminant that poses little or no health risk to those drinking the water daily fora lifetime, including sensitive or highly exposed people, MDH Health Risk Limits for 1,4-Dioxane Du "ration HRL Subchronic (>30 days up to 10% of a 300 ipph) * Health Endpoint" "" ; " lifetime} Liver, kidney, and respiratory systems Chronic (>109'0 of a lifetime) 100 Liver, kidney, and respiratory systems Lifetime (070 years) 1 Cancer *HRLs are shown in units of parts per billion (ppb). This is the same as micrograms per liter {}gig/L);