*Dose Conversion Factors & Assumptions: Converted dose calcu- 

 lated from actual food consumption data 



IA2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD) 



Twenty male and 20 female Wistar KFM-Han (outbred) SPF 

 rats/treatment group were administered 0, 0.2, 0.8, 4, 20, or 100 ppm 

 lindane (99.85%) in the diet. After 12 weeks, 15 animals/sex/group 

 were sacrificed. The remaining rats were fed the control diet for an 

 additional 6 weeks before sacrifice. No treatment-related effects were 

 noted on mortality, hematology, clinical chemistry, or urinalysis. Rats 

 receiving 20 and 1(X) ppm lindane were observed to have greater-than- 

 control incidence of the following: liver hypertrophy, kidney tubular 

 degeneration, hyaline droplets, tubular distension, interstitial 

 nephritis, and basophilic tubules. Since these effects were mild or rare 

 in animals receiving 4 ppm, this represents a NOAEL. The reviewers 

 of the study calculated the dose to be 0.29 mg/kg/day for males and 0.33 

 mg/kg/day for females, based on measured food intake. 



In a 2-year feeding study (Fitzhugh, 1950), 10 Wistar rats/sex/group 

 were exposed to 5, 10, 50, 100, 400, 800, or 1600 ppm lindane. Slight 

 liver and kidney damage and increased liver weights were noted at the 

 1(X) ppm level. If a food intake equal to 5% body weight is assumed, a 

 NOAEL of 2.5 mg/kg bw/day (50 ppm) can be determined from this 

 assay. In a 2- year bioassay (Rivett et al., 1978), four beagle 

 dogs/sex/group were administered 0, 25, 50, or 100 ppm lindane in the 

 diet. Treatment-related effects noted in the animals of the 100 ppm 

 group were increased serum alkaline phosphatase and enlarged dark 

 friable livers. A NOAEL was determined to be 50 ppm (1.6 mg/kg 

 bw/day). 



I.AJ. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD) 



UF = 1000. A factor of 10 each was employed for use of a subchronic 

 vs. a lifetime assay, to account for interspecies variation and to protect 

 sensitive human subpopulations. 

 MF= 1 



I.A.4. ADDITIONAL COMMENTS (ORAL RfD) 



Data on reproductive effects of lindane are inconclusive. Most reports 

 indicate that hexachlorocyclohexane isomers are nonteratogenic. 



IA.5. CONFIDENCE IN THE ORAL RfD 



Study: Medium 

 Data Base: Medium 

 RfD: Medium 



The principal study used an adequate number of animals and measured 

 multiple endpoints. Since there are other reported chronic and sub- 

 chronic studies, confidence in the data base is medium. Medium 

 confidence in the RfD follows. 



LA.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD 



U.S. EPA. 1985. Drinking Water Criteria Document for Lindane. 

 Prepared by the Office of Health and Environmental Assessment, 

 Environmental Criteria and Assessment Office, Cincirmati, OH for the 

 Office of Drinking Water, Washington, DC. The RfD in the Drinking 

 Water Criteria Document has been extensively reviewed by U.S. EPA 

 scientists and selected outside experts. 



