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ob/lb/96 FRI 16 50 FAA 91b dbb 7Uld Kf.h11kb1SLUlrK �� blWALIUA lgj00 Chemical Summary Methyl-Ten-Butyl Ether - Microsoft Internet Explorer Page 6 of 13 B. Acute Effects Limited information indicate that ambient levels of MTBE do not pose a health risk to healthy individuals; however, susceptible subpopulations laving under unique climatic condition (i e , ' subartic) may be adversely affected by volatile emissions from MTBE-blended gasoline Animal lethality data indicate that MTBE is low in acute toxicity The main target organ of acutely toxic doses of MTBE is the nervous system. 1 Humans - In controlled clinical tests in which healthy individuals were exposed to 5 mg MTBE/m3 for I hour, no symptoms of adverse effects were observed (U S. EPA 1993c) The concen-tration of 5 mg/m3 for I hour is roughly equivalent to a dose of 0 09 mg/kg see end note 1) . The individuals were evaluated for symptomatic responses (headaches, throat and nasal irritation, cough, and dizziness) , neurobehavioral changes, upper airway inflammation, and eye inflammation. Complaints of headaches, eye irritation, nose and throat irritation, cough, nausea, dizziness, and spaciness were recorded in two cities in Alaska following the introduction of MTBE-blended gasoline during the fall of 1992 (U S. EPA 1993c) Similar effects could not be identified in popu- latxons in New Jersey or Connecticut where MTBE-blended gasoline was also used. U S EPA (1993c) notes that "There is unlikely to be a substantial risk of acute health symptoms among members of the public receiving 'typical' environmental, exposures under ' temperate conditions (i e , not subarctic temperature) This leaves open the question about more subtle health risks, espe- cially among susceptible subpopulations. If acute symptoms are being caused by MTBE, they appear to be mild and transient" Humans are acutely exposed to MTBE as part of a medical treatment to dissolve cholesterol gallstones (U S EPA 1999) Injection of the gall bladder with MTBE can result in nausea, vomiting, ' sleepiness, and minor transient mucosal damage in the gallbladder. Intravascular hemolysis and renal failure have occurred following inadvertent extravasation of a large bolus of MTBE (U S EPA 1994) 2 Animals - Oral LD50 values of 1.6-3 9 g/kg have been reported for rodents (U S EPA 1993x) Acutely toxic oral doses can result in nervous system effects (see section G) as well as 1 uiub,uuldi we4kiiesb and LnfldltuucLLxoll of Lhe sLUmauh tad b1Qdll intestines Inhalation LC50 values of 85-192 g/m3 have been reported in rodents (U S EPA 1993a) Symptoms of inhalation exposure include nervous system effects (see section G) , as well as inflammation of the nasal mucosa and trachea. MTBE also causes mild skin irritation (slight erythema and edema) and moderate eye irritation (corneal opacities, chemosis and conjunctival redness) (U S EPA 1993a) A skin penetration LD50 ' of >10 mL/kg has been reported for rabbits (Clayton and Clayton 1981-82) MTBE is not expected to be a primary skin irritant (HSDB 1999) ' C Subchronic/Chronic Effects Information on the subchronic and chronic toxicity of MTBE to humans was not found in the secondary sources searched. Laboratory rodents exposed to high doses or concentrations of MTBE exhibit blood chemistry changes and kidney abnormalities. 1 Humans - No information specific to MTBE was found in the available literature AS,asldSls Th-1 IFTBQ buy �.a+l.,u L...1 .aa Friday, August 16, 1996 4 25 PM