Document Z40mb6mGJvmNeNQbyJxzymGK0

DRAFT Hazard from exposure to higher chlorodibenzodioxins a. The Centers for Disease Control accepts 1 pg/(kg body mass)/day of 2,3,7,8-TCDD as an acceptable daily intake. (R.D. Kimbrough, H. Falk, P. Stehr and G. Fries, J. Tox. Env. Health, 1984, 1A, 47-93) b. EPA is said to have accepted that amount as an Acceptable Average Daily Intake for calculating water-quality numbers. c. Other chlorodibenzodioxins are known to be less toxic in acute doses and to be less active in various biological effect tests than 2,3,7,8-TCDD. (See summary prepared by A. Peter, attached.) d. In particular, octachlorodibenzodioxin and 1,2,3,4,6,7,9heptachlorodibenzodixoin are found to be practically nontoxic. (See summary.) e. Background intake of 2,3,7,8-TCDD approximates 1 pg/kg/d. Intake of higher chloro cogeners is probably >5 pg/kg/d (by inference from body burden estimations). SUBJECT i 0 r 1 CO2.132 2. Exposure of tetrathal employees DRAFT a. Mean total chlorodibenzodioxin content of product (Samples //l-ll) is 68 ppb (68 pg mg"1 of tetrathal). b. Mean content of tetra- through heptachlorodibenzodioxin in product is 47 ppb (47 pg/mg tetrathal). c. Because tetrathal is irritating assume that dermal exposure can be neglected; thus inhalation affords the only significant route of exposure. Respiratory protection is worn; assume 90% protection and an inhalation volume of 10 m3/shift, a mean dust level of <2.9 mg tetrathal/m3 air (see J. Wolfsburger memo attached) and complete absorption of all inhaled dust. Thus tetrathal intake is 0.1 x<2.9 x 10 = <2.9 mg/d. d. Intake of all chlorodibenzodioxins is: <2.9 mg tetrathal/d x 68 pg CDD/mg tetrathal = <197 pg/d. e. Intake of tetra- through heptachlorodibenzodioxins is: <2.9 mg/d x 47 pg/mg = <136 pg/d. f. Assuming 70 kg body mass, intake becomes: 1. For all chlorodibenzodioxins, <197/70 = <2.8 pg/kg/d. 2. For C14-C17 dibenzodioxins, <136/70 = <1.9 pg/kg/d. JDV - 1 /2 3 /8 5 2 SUBJECT TO ri U-