REVIEW OF THE SELENIUM HEALTH CRITERIA DOCUMENT ------- PB89-109029 Review of the Selenium Health Criteria Document (U.S.) Environmental Protection Agency Washington, DC 19 jul 88 ------- ' 30277-Iffl REPORT DOCUMENTATION PAGE 1. REPORT NO. SAB-EHC-88-036 4. THI. end subtrti* Review of the Selenium Health Criteria Document PB89-109029 5. Report Data July 19, 1988 7. Author(») Metals Subcommittee I. Performing Organization Rapt. No. 9. Performing Orgrnlntlon Nam* and Addretl Environmental Protection Agency Science Advisory Board 499 S. Capitol Street, SW Washington, D.C. 20460 (A101F) 10. Prolect/Task/Work Unit No. II. Contnct(C) or Qrant(O) No. (C) (Q) 12. Spontorlnf Organization Ntmt ind Address Environmental Protection Agency 401 M STreet, SW Washington, D.C. 20460 IS. Type of Report & Period Covered Final Report 14. IS. Supplementary Notet 16. Abstract (Limit: 200 word*) Metals Subcommittee of the Science Advisory Board's Environmental Health Committee has completed its review of the Drinking Water Health Criteria Document for Selenium.dated December 1986. The review was conducted January _14- 15, 19%jT~a"€' the ~StT James Hotel in Washington, D.C. C^The Subcommittee made" two recommendations; that more informatio'n was needed in the document on the studies on which the standard is based and that the Drinking Water Equivalent Level (DWEL) should be 200 roicrograms/L based on an uncertainty factor of 10. The Committee observed that the Environmental Protection Agency for • its suggested drinking water equivalent level has chosen a factor 15 and are to be able to balance the dat?. from Yang et al (1983) and the National Academy of Sciences 1980 conclusion that the safe range of daily selenium intake if 50 to 200 microgram. The Subcommittee further recommended that because the Yang et al study and the National Academy of Sciences recommendation plays such an important role in the development of the drinking water equivalent level, that more detail be more redefined concerning these study. 17. Document Analysis a. Descriptors Metals Subcommittee/ Environmental Health Committee b. ld*ntifl«r(/Op*n.Cnd*d Terms c. COSATI Field/Group II. Availability Statement 19. Security Claaa (Thlt Report) 21. No. of Pa»t 20. Security Claaa (Thlt Pafa) (See ANSI-Z39.18) See Instructions on Ravers* OPTIONAL FORM 272 (4-77) (Formerly NTIS-35) Department of Commerce ------- UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON. D.C. 20460 July 19, 1988 OFFICE or THE ADMINISTRATOR SAB-EHC-88-037 Honorable Lee M. Thomas Administrator U.S. Envorinmental Protection Agency 401 M Street, S.W. Washington, D.C. 20460 Subject: Science Advisory Board's review of the SELENIUM health criteria document Dear Mr. Thomas: The Metals Subcommittee of the Science Advisory Board's Environmental Health Committee has completed its review of the Drinking Water Health Criteria Document for Selenium dated December 1986^'The review was conducted January 14-15, 1988 at the St. James Hotel in Washington, D.C. The Subcommittee made two recommendations; viz, 'that more information was needed in the document on the studies on which the standard is based and that the DWEL should be 200 micrograms/L based on an uncertainty factor of 10. conclusion in the criteria document that the Drinking Water Equivalent Level (DWEL) should be 107 micrograms/L is based mainly on the Yang et al (1983) study and the National Academy of Sciences (HAS) 1980 conclusion that the safe and adequate range of daily selenium intake is 50-200 micrograms. One justification for setting the DWEL at this level is that drinking an average of 2 liters per day would provide close to the upper limit of 200 micrograms per day. To arrive at this conclusion it was necessary to set the uncertainty factor at 15, a somewhat unusual value but the only one that would allow both the use of the Yang et al study and also give an allowable intake close to the upper limit of the NAS recommendation. The report properly focuses on the selenium dilemma: the apparently narrow margin between minimal daily intakes required to maintain health and intakes associated with toxicity. The primary source of data for establishing the DWEL is the report of Yang et al (1983) . The Subcommittee recommends that this report be discussed at greater length because of the reliance placed upon it. For example, the authors discuss two areas labelled as high selenium areas. In one, selenosis was common in livestock and toxic signs were apparent in humans. In the other, selenosis ------- "has naver been reported. In the tables, however, the first area is seen to be associated with hair and blood levels about eight times higher that measured in the second. If 3.2 mg/day of selenium is estimated as the LOAEL, based or. the first area, then 400 ug/day would represent a level below the NOEL. To be consistent, then, the language in the document should reflect the concept that the National Academy of Scieces figures may overestimate the uncertainty margin. Morever, even in high selenium areas, drinking water seems to be an insignificant contribution to total intake. If Yang et al are correct in their assertion that the ratio of toxic to minimal blood levels is about 16, a figure not too deviant from the NAS value, then the uncertainty factor could be set to 5-10 without compromising safety and without jeopardizing a possibly useful source of this essential element. Also, the 70 kg standard EPA human is probably not representative of the Chinese population, another margin in the uncertainty calculation. Because the Yang et al study and the NAS recommendation play such an important role in the development of the DWEL, it is recommended that more detail be provided regarding the studies. The Yang et al study is not clearly described in the criteria document and it is not clear what the minimum daily intake of 3200 micrograms/day (LOEL) used in deriving the DWEL refers to. Does the study deal with individuals or geographic areas? How many people were involved? How was selenium intake measured? Also more information is needed on how the NAS arrived at its recommendation of 50-200 microgram daily intake value. A second recommendation is that the USEPA consider raising the DWEL to 160 micrograms/L by using an uncertainty factor of 10 instead of 15. Rounding off to one significant figure could lead to a DWEL of 200 micrograms/L. The reasons for this are as follows: 1. In the Yang et al study the LOEL was 3200 micrograms per day and no lower values have been reported. ! 2. A statement on page VI-30 that chronic human ingestion of 200 micrograms per day may be related to increased incidence of symptoms is not supported by any of the data presented other than the NAS report. 3. A daily intake of 214 micrograms (107 micrograms/L x 2 L/day) is too close to the value needed for human nutrition (50- 200 micrograms per day) and too far from the lowest value at which human symptoms occur. 4. There is little or no evidence for proposed human health effects such as cancer or teratogenic effects. Selenium (SeS2+) is not regarded as a human carcinogen. 5. Uncertainty factors should reflect likely beneficial effects as well as harmful effects. There is limited evidence that selenium deficiency is related to cancer and perhaps cardiovascular disease. ------- Sincerely, Norton .Nelson, Chairman Executive Committee Richard A. Griesemer, Chairman Environmental Health Committee Bernard Weiss, Chairman Metals Subcommittee ------- !:e:als b'ubcemr.iccee Dr. Bernard \ieiss [Chair], Professor, Division of Toxicology, P.O. Box KBB, University or Rochester, School of Medicine, Rochester, MY 14642 (716) 275-3791 Dr. Ronald Wyzga [Vice-chair], Electric Power Research Institute, 3412 Hillvieu Avenue, P.O. Box 1041, Palo Alto, California 94303 (415) 855-2577 Dr. Thomas Clarkson, Professor and Head, Division of Toxicology, University ot Rochester, School of lledicine, Post Office Box RBB, Rochester, New York 14642 (716) 275-3911 Dr. Gary Diamond, Assistant Professor of Pharmacology, University ot Rochester School of Medicine, Rochester, New York 14642 (716) 275-5250 Dr. Phil Enterline [LNVIKOMIENTAL HEALTH CCttllTTEE], Department of Biostatistics, Graduate School of Public health, University of Pittsburg, 13U Desoto Street, Pittsburgh, PA 15261 (412) 624-3032 Dr. Robert Goyer, Department of Pathology, Health Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A5C1 • • Dr. liarvin Kuschner, Dean, School of lledicine, Health Science Center, Level 4, State University of New York, Stony Brook, New York 11794 (516) 444-208U Dr. Brooke T. Mossman, Department of Pathology, The University of Vermont, Medical Alumni Building, Burlington, Vermont 05405-0068 (802) 656-2210 Dr. Gunter Oberdoerster, Associate Professor, Radiation Biology and Biophysics Division, University of Rochester, School of Medicine, 400 , Elmwood Avenue, Rochester, N.Y. 14642 (716) 275-3804 Dr. F. William Sunderman, Professor of Laboratory tiedicine and Pharmacology and head, Department of Laboratory Medicine, University of Connecticut Health Center, Room C 2021, Farmington, Connecticut 06032 (203) 674-2328 Executive Secretary Dr. Richard Cothern, Executive Secretary, Environmental Health Committee, Science Advisory Board [A-101F], U.S. Environmental Protection Agency, Washington, D.C. 20460 (202)382-2552 ------- |