Document VJ8Zm2L8XQej9Q5k5Xr5aGYEN

11-18-96 S:44 PM i PB&B PATTON BOGGS, L.L.P. 2550 M STREET. N.W. WASHINGTON. D-C. 20037-1350 1202) 457-6000 WRITER'S DIRECT DIAL (202) 457-5270 November 18, 1996 MEMORANDUM FOR THE HAP TASK FORCE Re: 1.1.2-Trichloroethane Reproductive andDevelopmental Toxicity Attached, as discussed at the meeting last week, is a proposed insert to the ECA proposal for 1,1,2-trichloroethane addressing the absence of need for reproductive or developmental toxicity testing. You will note a number of statements which need to be confirmed. Most of these relate to our assertion that 1,1,2-trichloroethane is linked to EDC production; the TRI data may indicate otherwise. I will look primarily to Bill Hayes for assistance on this issue, but would be pleased to hear from any of you if you have information. Please let us have any comments by close of business Wednesday, November 20. Attachment cc: Michael L. Gargas, Ph.D. W, .ffl DO 1?9777 OONFTDFNTTAl 1,1-18-36 5:44 PM ; PB&.B 5.0 Developmental and Reproductive Toxicity Studies. With the exception of a postnatal mouse screening test, no study of the developmental or reproductive toxicity of 1,1,2-trichIoroethane has been identified in the scientific literature. Accordingly, it is not possible to use route-to-route extrapolation to determine the developmental or reproductive effects of 1,1,2-trichloroethane following inhalation exposure. As discussed below, however, any concern as to developmental or reproductive risk posed by 1,1,2-trichloroethane is largely theoretical, based on the extremely low level of human exposure and EPA's position, accepted by the HAP Task Force, that 1,1,2-trichloroethane-should be regulated as a potential carcinogen. It should also be noted that structurally similar compounds, such as 1,1,1-trichloroethane and ethylene dichloride (EDC), have not shown significant developmental or reproductive toxicity when tested [Confirm]. The extremely low human exposure to 1,1,2-trichloroethane is due to the fact that virtually the entire U.S. production of 1,1,2-trichloroethane is as a captive or "site-limited" intermediate, generally as abyproduct of the production of EDC? Thus, 1,1,2-trichloroethane is found primarily in the vicinity of EDC production facilities [Confirm]. The one manufacturer that markets 3 1,1,2-trichloroethane sells less than/million pounds annually [Confirm]. Available data on the concentrations of 1,1,2-trichloroethane in the environment are consistent with the foregoing paragraph. The Agency for Toxic Substances and Disease Registry (ATSDR) has stated that "[w]here 1,1,2trichloroethane is found, levels appear to be about 10-50 ppt (parts per trillion]." Toxicological Profilefor 1,1,2-Trichloroethane (1989), 63. These -V , -A . 11-18-96 6:44 PM ; PB81B 2- - concentrations would have been undetectable without advances in detection capability. The low environmental exposure is consistent with available information as to use. ATSDR found that "[n]o use with significant consumer and general population exposures has been identified." Id., 61. Moreover, there is some doubt as to whether 1,1,2-trichloroethane meets the criteria articulated in EPA's so-called "B policy" for "substantial release" and "substantial human exposure," as will be addressed in greater detail in the comments of the HAP Task Force on the proposed test rule. For present purposes, it may be noted that the preamble to the proposed test rule does not identify any exposure as meeting the threshold for "substantial human exposure" except for 1,036 workers -- the threshold being 1,000 workers. The HAP Task Force will be providing a better) estimate of the number of workers actually exposed to 1,1,2-trichloroethane as \ part of its comments. On top of the fact that human exposure to this site-limited intermediate is extremely low, EPA's regulatory structure would appear to make superfluous any determination as to the reproductive or developmental toxicity of 1,1,2-trichloro ethane. As discussed above, the most significant potential exposure would appear to be from production facilities fofEDC |onfirm], Beth EDC and 1,1,2trichloroethane obviously are subject to regulation under the MACT standards for chemical production facilities, and any additional controls imposed as part of the \)0 c. ** residual risk determination foi*EDC will reduce exposure to 1,1,2-trichloroethane [Confirm]. The Agency's Integrated Risk Information System (IRIS) lists a unit risk estimate or cancer potency for 1,1,2-trichloroethane of 1.6 x 10 5. The maximum 8-hour time-weighted-average (TWA) exposure allowed for ' DO CONFIDFNTTAl 11-18-96 6:44 PM ;PBfeB -3- 1,1,2-trichloroethane is 10 parts per million, 29 C.F.R. 1910.1000, Table Z, and the American Conference of Governmental Industrial Hygienists (ACGIH) lists it as an animal carcinogen (A3). In drinking water, the maximum contaminant level goal (MCLG) is 3 jig/1, which according to EPA corresponds to a theoretical cancer risk of 10*s, and the maximum contaminant level (the enforceable limit) is 5 /xg/I, the same as for organic contaminants which have an MCLG of zero. The HAP Task Force is aware of no instance where the allowable exposure level for a substance so regulated has ever been reduced on account of such substance being identified as a reproductive or developmental toxin. A specific illustration of these points is provided by an evaluation of 1,1,2-trichloroethane at the fenceline of one of the fewer than 20 U.S. facilities where EDC is produced, specifically, the Dow Chemical Company facility in Lake Jackson, Texas. Actual monitoring data iimn^iately^sutsideme facility showed that out of 306 samples, 97% were non-detects at 0.55 fig/m2. Only three values exceeded the detection limit. Put another way, only three samples exceeded an upper bound cancer risk of 9 x 10'6 (using the EPA unit risk estimate of 1.6 x JO*5). It appears inconceivable that significant reproductive or developmental toxicity effects would result from current or future anticipated exposure scenarios for 1,1,2-trichloroethane. DO 1?9?30 GONFTDFNTT A(