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WATER G'REML:IN PUBLIC WEALTH Ns5ESS•MENT: P:U:B-1.11C CONfMENT'DRAFT <br />TCE Exposure <br />While air modeling can.estimate the TCE concentrations in outdoor air for specified times and locations, <br />such estimafes-Will differfrom an individ.u.al's actual exposure to TCE (that Is, bow much TCE enters the <br />body through breath1ng): The amount a. person breathed in would*be�.highly varlable, depending.on how <br />much time they spent in different locations and what the TCE concentrations wereAuring-those times. <br />In addition, -other factors -,such. as body size, breathing rate, type and1ievei of activitieg,..amount of time <br />spent lndoors.vs outdoors, -etc. could all -influence how much TCE a person was exposed to. Estimated air <br />coiiceritrations provide limited inforibation about real exposures individuals might have received. <br />TCE is also commonly detected:at very low -concentrations in indoor and outdoor air. Most people are <br />exposed to small amounts of TCE,typlcally at levels far below those known to affect health. Most TCE <br />used in the U.& is. released'into the air by evaporation, primarily from degreasing operations (ATSDR, <br />2019). lt'is'also-still used as a spot cleanerat some dry cleaners: The Continual release of TCE from many <br />small sources account for its detect.lon at very low levels in oudooralr at MPCA's metro area <br />monitoring sites. People can also be exposed to TCE present -in products such As adhesives, paint <br />removers; cleaneirs,.and varnishes. <br />Understanding TCE Air Concentrations <br />The following table provides additional context about the occurrence and potential risk at different TCE <br />concentrations in air. <br />Table 1: Understanding TCEAirConcentrations: <br />4 E,.;ca' 'en `ratio m. <br />G ri <br />2017 average outdoor air concentration.atthe nearest MPCA air monitoring site (Harding <br />All� <br />High School] <br />Average indoor air.concehtrati:ons in.three Twin Cities communities in 1999 <br />0.5 <br />- <br />- ---I <br />(Sexton,t a1.,.2004) <br />2 <br />U.S. EPA (2011)/MDH Health -Based Value -poses little to no health risk. over A lifetime <br />N20� <br />Estimated 11h 100,p00 In cancer risk.over a.lifetirne <br />20 <br />- <br />A small risk of fetal heart.defects for pregnant women during the first eight weeks of <br />^30: <br />(U,S. EPA..2D11,-based on a rodent study) <br />[pregnancy <br />Estimated 1 in 10,000 increased cancer risk over a lifetime <br />200 <br />A small risk of kidney effects with continuous exposure over a long time (U.S. EPA, 2011; <br />-200 <br />based on a rodent study) <br />Estimated 1 in 1,000 increased cancer risk over a lifetime <br />55;000 I <br />small risk for decreased thymus weight (immune system effects) with continuous <br />> 100,000 y <br />exposure over a long time (U.S. EPA, 2011;: based on a rodent study) <br />IAmerican Conference ofGovern menta1.Industrial Hygienists 8-hour worker standard <br />_.._.-........ <br />-116,900 <br />Concentration at which. some. workers. experienced health effects in studies, including <br />270,000 <br />fatigue;headache, eye irritation, and. an increase. in kidney cancer (U.S. EPA; 2014 <br />11 <br />