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The Past Suppression of Industry Knowledge of the Toxicity of Benzene to Humans and Potential Bias in Future Benzene Research PETER F. INFANTE, DDS, DRPH Petrochemical industry representatives often withhold information and misinterpret positive evidence of toxicity of benzene, even from their own research, also discouraging or delaying disclosure of findings of adverse effects to the public. They now appear to be attempting to influence study results in industry's favor by offering predetermined conclusions about study results as part of an effort to draw financial support for the studies. The American Petroleum Institute is currently raising funds for benzene research being conducted in China for which it has already announced the intended conclusions. Key words: benzene; industry ethics; leukemia; blood disease; bias; petrochemicals. INT J OCCUP ENVIRON HEALTH 2006;12:268272 S everal publications have recently addressed the issue of the role of industry and its researchers in the evaluation of the toxicity of industrial exposures to workers. Gennaro and Tomatis concluded that epidemiologic research funded by the petrochemical industry is likely to underestimate or fail to detect increased risks of cancer and other diseases among industrial workers because of the use of inappropriate methods and study design protocols.1 They claim that these results in turn have negatively impacted public health. More recently, Michaels et al. have provided information showing that the chemical industry withheld from the Occupational Safety and Health Administration (OSHA) epidemiologic study results that demonstrated a significantly elevated risk of lung cancer among workers exposed to low levels of hexavalent chromium (CrVI). 2 As a result, the findings were not included in OSHA's analysis of data related to its recently promul- The author is Adjunct Professor of Environmental and Occupational Health, School of Public Health and Health Services, The George Washington University, Washington, DC. He was formerly employed by the U.S. Government. For three years (19751978), he served as an epidemiologist with the National Institute for Occupational Safety and Health. For 24 years, he served as a senior health scientist and Director of the Office of Carcinogen Identification and Classification (19781983) and Director of the Office of Standards Review (1983 2002), Health Standards Program, Occupational Safety and Health Administration. Address correspondence and reprint requests to: Peter F. Infante, 200 S. Oak Street, Falls Church, VA 22046, U.S.A.; phone: (571) 6413047; e-mail: <pinfante@starpower.net>. gated standard to protect workers from exposure to CrVI.3 On the other hand, Barrow and Conrad have argued that a wide variety of mechanisms enable policymakers and the public to assure themselves that studies performed or funded by industry are identified as such, meet high scientific standards, and are not suppressed when their findings are adverse to industry's interests.4 My 27 years of experience through employment with a federal research agency (NIOSH) and regulatory agency (OSHA) leads me to conclude that petrochemical industry representatives and their contractors often withhold information from the Federal Government and misinterpret positive study findings by others. To support my view, I present examples of the petrochemical industry's behavior related to toxicological research on benzene. These examples, drawn from professional experience as a health scientist, demonstrate that industry representatives often have not readily disclosed information about the toxicity of benzene from their own research. They have also tried to discourage or delay disclosure to the public of findings by their own researchers who observed adverse effects from low-level exposures to benzene. In two of the examples presented, the senior investigators resigned from their industry research positions because their research findings of toxicity from lowlevel benzene exposures were being withheld from submission to scientific journals. In the third example, the industry tried to intimidate a government employee from doing his job of seeking toxicological data related to benzene exposure and toxicity while a standard was being developed by the Federal Government. Negative industry influence on data related to benzene toxicity may not be limited to the past. Industry representatives give the appearance of attempting to influence study results in industry's favor by offering predetermined conclusions about study results as part of an effort to draw financial support for the studies; specifically, the American Petroleum Institute (API) is currently raising funds for benzene research being conducted in China for which it has already announced the intended conclusions. INDUSTRY'S IMPEDING RELEASE OF RESEARCH DATA ADVERSE TO ITS INTERESTS Example 1--Dow Chemical Company Withholding Data from OSHA. In 1977, while OSHA was engaged in rule- 268 making to lower the eight-hour time-weighted average (TWA) exposure limit for benzene from 10 ppm to 1 ppm,5 the Dow Chemical Company initially withheld from OSHA, and the public in general, information that indicated that Dow Chemical workers exposed to benzene levels below the exposure limit in effect at the time (10 ppm) demonstrated a significantly elevated risk of chromosomal breakage.68 The official hearing record to receive evidence for the benzene standard closed on September 2, 1977. The final standard was issued on February 10, 1978.9 Only after several exchanges of correspondence between NIOSH and Dow Chemical Company representatives that took place between October 31, 1977, and March 1, 1978, did the company finally release the study results to NIOSH, and to EPA, under Section 8(e) of TSCA.1015 The release of the information, however, took place on March 1, 1978, more than four months after the benzene record closed. Yet, the study results were available by March 1977, six months prior to the close of the hearing record.16,17 This delay likely constituted a legal violation of TSCA reporting, which requires the information to be submitted within 15 working days. A dispute between Dr. Picciano, the senior author of the study, and Dow Chemical Company over the benzene exposure data related to the adverse chromosomal effects seen in the workers resulted in his resignation from the Dow Medical Research Department. Dr. Picciano has stated that the peer-review process for the benzene study, which showed adverse effects on the DNA of blood lymphocytes, took nine months, while a study of another chemical that showed no adverse effect sailed through in six weeks even though the latter study was based on similar atmospheric sampling data.17 Because the Dow cytogenetic study of benzeneexposed workers was not part of the hearing record, Department of Labor attorneys could not introduce it as evidence of benzene toxicity to DNA resulting from exposure below 10 ppm, e.g., the occupational limit in effect at the time, as part of the benzene case before the 5th Circuit Court of Appeals. OSHA's Director of Health Standards at the time was of the opinion that if the information had been obtained earlier, "it would have been useful evidence."17* Example 2--The Chemical Industry Institute of Toxicology Withholding Data from OSHA. In 1980, the U.S. Supreme Court upheld the 5th Circuit Court of Appeals' stay of the OSHA 1978 Final Benzene Standard. Therefore, in 1983, OSHA began working on the development of a new benzene standard.18,19 In view of the fact that OSHA was considering proposing a 1 ppm eight-hour TWA exposure limit for benzene, the Agency wrote to the Chemical Industry Institute of Toxicology (CIIT) to inquire about the results of a cytogenetic study that sup- *The API sued OSHA for a stay of the 1977 Benzene Standard in the 5th Circuit Court of Appeals. OSHA lost the case. posedly demonstrated sister chromatid exchanges (SCE) in peripheral blood lymphocytes and micronucleus induction in bone marrow erythrocytes in rats exposed to 1 ppm benzene for a single six-hour period. Through exchanges of correspondence with CIIT, government scientists made several attempts to obtain the data, but to no avail. 2024 The study results were finally released on the day following the appearance of an article in the Durham Morning Herald entitled "Park Lab Denies Delaying Results of Benzene Tests."25,26 Yet, these study results were available months prior to the release of the data (personal communication Dr. Andrew Kligerman).27 In a situation similar to Dr. Picciano's resignation over the withholding of the Dow cytogenetic study results, the senior investigator of the CIIT study, Dr. Kligerman, left the organization over a dispute with upper-level management revolving around the study findings and the withholding of the data from the public. Prior to the release of the study, however, researchers at the CIIT were required to add an additional statistical test to the results related to the findings (Dr. A. Kligerman, personal communication). This new test did not show a statistically significant result for SCEs and micronuclei related to the 1 ppm benzene exposure level in the rats. Thus, the report was released with two statistical tests for the same data points, one demonstrating a statistically significant result from benzene exposure of 1 ppm for a single six-hour period and the newly added test indicating no significant excess of chromosomal breakage at the 1 ppm level Example 3--Shell Oil Company Withholding Data from OSHA. In 1983, OSHA published a Request For Information (RFI) concerning benzene exposure in the workplace.18 In response, the Shell Oil Company provided OSHA with preliminary analyses from a mortality study of workers employed at its Wood River, Illinois, and Deer Park, Texas, facilities.28 The studies indicated an elevated risk of leukemia among both refinery populations. Since Shell researchers had previously published a report describing a health surveillance system for Shell employees,29 an OSHA official requested data from the Shell Safety and Industrial Hygiene Department for individuals employed at its Wood River refinery. He requested information for individuals who demonstrated blood abnormalities along with their benzene exposure levels.30,31 OSHA was informed on two occasions that Shell had no workers exposed to benzene who demonstrated blood abnormalities.32,33 Further, the Shell Manager of Safety and Industrial Hygiene wrote to the Director of OSHA asking that he stop the employee from requesting such data because it was putting a strain on Shell's working relationship with OSHA. As stated by Mr. Kusnetz: It appears to us that Infante is seeking data to support a conclusion he has already drawn . . . this, we find unscientific and harassing . . . the kinds of tac- VOL 12/NO 3, JUL/SEP 2006 www.ijoeh.com Bias in Industry Benzene Research 269 tics used by Infante put an unnecessary strain on . . . cooperation . . . we hope that you will assist in alleviating that condition.34 This letter was clearly an attempt on the part of Shell Oil Company to intimidate a government official so he would not pursue the data on benzene exposure and blood abnormalities among the Shell Wood River workforce. Subsequently, a third letter was written to the Shell Medical Department requesting its data on benzene exposure and blood abnormalities.35 The letter further stated that Shell's personal attacks on the character of the government employee in their previous letters served only to divert attention from issues related to the toxic effects of benzene on workers. The tactic also gave the appearance to OSHA that Shell might be withholding data from OSHA. In response to this letter, Dr. Joyner and Mr. Kusnetz provided OSHA with data for their workers with blood abnormalities who were assigned benzene-exposure jobs along with their benzene exposure levels--data the company had claimed did not exist in responses to earlier requests.36 Above, I provide three examples of situations in which industry and its researchers withheld important data from a Federal Government regulatory agency during rulemaking. These data were important because they demonstrated an elevated risk of chromosomal breakage in workers and in experimental animals resulting from benzene exposure levels close to or at the newly promulgated TWA limit of 1 ppm. They also indicated that benzene exposures prevailing in refineries at the time were resulting in blood abnormalities among benzene-exposed workers, who were being followed in a medical surveillance program similar to one that had been proposed by OSHA. The Irony of the Behavior of a Shell Corporate Employee. In the case of the Shell Oil Company, the Corporate Medical Department not only withheld data, but also tried to intimidate a government employee, who was acting on behalf of the Agency, from doing his job. The irony of the latter situation is that shortly after the Shell corporate employees withheld data on blood abnormalities from OSHA, Shell's Manager of Safety and Hygiene, H. L. Kusnetz, published an editorial accusing NIOSH of acting in a "blatant scientifically unethical manner" because NIOSH had released a pre-publication update of its study of Pliofilm workers exposed to benzene prior to the report's having undergone "the agency's review process."37 The new study included a quantitative risk assessment for benzene exposure and leukemia--an assessment that This claim was false. From my experience of having worked at NIOSH, all publications are required to pass extensive internal peer review before they can be submitted to a journal for publication. Furthermore, R. Rinsky also acknowledged that the study had undergone internal NIOSH peer review prior to any discussion with the press (personal communication). OSHA needed to consider in its benzene rulemaking.38 One can only suspect that Mr. Kusnetz wrote the editorial criticizing the "premature release" of the NIOSH benzene risk assessment because he did not want OSHA to rely upon it during its evaluation of data related to the development of its 1987 Benzene Standard.19,39 INTERPRETATION OF EXISTING DATA, AND BIAS IN FUTURE BENZENE RESEARCH Misinterpretation of Existing Data. Concern about the toxicity of benzene is not an issue of the past. Since the late 1980s, publications have appeared that have evaluated the toxicity of benzene exposure among workers in China, resulting from studies conducted jointly by the U.S. National Cancer Institute (NCI) and the Chinese Academy of Preventive Medicine (CAPM). Their study results have demonstrated a dose response for leukemia as well as one for non-Hodgkin's lymphoma (NHL) among benzene-exposed workers.40 The levels of exposure associated with elevated risks of leukemia and other blood diseases were much lower than those previously reported. (The dose response for benzene exposure and NHL was a new finding.) A recent study by this team of investigators has also demonstrated bone marrow toxicity among workers resulting from benzene exposure levels below 1 ppm--the current occupational limit in the United States.41 The latter finding of blood abnormalities resulting from benzene exposures below 1 ppm confirmed the results of an earlier study.42 The findings reported by Hayes et al.,40 however, have been challenged by Wong and Budinsky, et al.43,44 These investigators are of the opinion that only highlevel exposures to benzene can cause blood diseases, including leukemia. They also opine that the NCI/CAPM study40 suffers from errors in benzene exposure estimation and that these errors may be responsible for low-level benzene exposure's demonstrating adverse effects on the hematopoietic system, as observed in the NCI/CAPM study. Hayes et al. have responded that the critics had misinterpreted earlier literature reports on benzene's adverse effects on leukocyte counts from low-level benzene exposures, and had failed to consider more recent literature (up to 1996) indicating that there was no evidence of a threshold below which benzene does not cause hematotoxicity.45 They also provided evidence indicating that Wong and Budinsky et al.43,44 had made incorrect assumptions about the NCI/CAPM exposure estimation procedures used in the NCI/CAPM dose-response analyses. Hayes et al.45 concluded that their earlier findings40 provided new information regarding low-level benzene exposure and leukemia, and also that benzene may cause other lymphohematopoietic cancers. Appearance of Bias in Future Industry-funded Benzene Research. Recently, in what appears to be an effort to 270 Infante www.ijoeh.com INT J OCCUP ENVIRON HEALTH counter the findings from the NCI/CAPM study, the API has collected $27 million from member companies to fund research in Shanghai, China.46 In an effort to solicit money for the study, prior to its commencement, the API presented to its member companies what appears to have been a PowerPoint presentation of the "expected results" of the "Shanghai study." According to the presentation, the research results are expected to "affect" significant issues of global financial concern to the petroleum industry, such as requirements to reformulate gasoline, requirements to clean up petroleum-contaminated soil and water, requirements to reduce benzene exposures from refineries and marketing facilities, and litigation costs for individuals contracting leukemia and other hematopoietic diseases.46 The PowerPoint presentation apparently sent to Craig Parker, Manager of Toxicology and Product Safety, Marathon Oil Corporation, states that the planned research results will enhance industry's ability to achieve the above-mentioned objectives, as the findings of the "Shanghai study" are expected to: a) provide strong scientific support for the lack of a risk of leukemia or other hematological disease at current ambient benzene concentrations to the general population; b) establish that adherence to current occupational exposure limits (in the range of 15 ppm) do not create a significant risk to workers exposed to benzene; c) refute the allegation that Non-Hodgkin's lymphoma can be induced by benzene. The drawing of such conclusions prior to the commencement of the study provides evidence of potential bias in the outcome of the study. Others also have expressed concern about bias in this study.46 If the findings of the study turn out to be similar to those expressed prior to the commencement of the study, they will be difficult to accept unless a research organization that does not have an invested interest in the outcome is given the responsibility to complete the study. The validity of research findings related to additional issues of benzene toxicity also may be questioned. Therefore, in order for the findings to merit scientific credibility, it may be most beneficial for the API and for occupational health in general to turn the research activities for the Shanghai study over to the NIOSH or to the NCI. Letters have been sent previously to member organizations of the API requesting the transfer of the research to an independent body in order to remove "any built-in bias" in the study results.47 The NCI has been conducting research in China for more than 15 years and clearly has experience in working with Chinese investigators. The NCI also has experience in dealing with methodological issues that may arise during the conduct of the study. CONCLUSIONS My past employment in governmental research and regulatory agencies allowed me to interact with industry's representatives and its researchers for 27 years. As a result of this experience, it is my belief that industry's research findings are sometimes suppressed when the results are not in the interest of the industries funding the studies. Furthermore, in the two examples of cytogenetic data being withheld from OSHA, and the from public in general, both senior investigators, who were employed by industry or by an industry-funded research facility, resigned from their toxicology positions because of disputes with upper-level management about the way in which their reports were being handled internally. These observations also imply that industry researchers with the integrity to stand up to corporate management regarding the adverse effects of products on workers may lose their jobs. Research on benzene currently being carried out in China through funding by the American Petroleum Institute suggests a bias in future study results. This potential bias is indicated by a priori conclusions about the study results that were developed by those involved in the solicitation of funding for the research. It is recommended that the "Shanghai study" be turned over to the NIOSH or to the NCI for its completion. To do otherwise may result in the findings having little scientific credibility. References 1. Gennaro V, Tomatis L. Business bias: how epidemiological studies may underestimate or fail to detect increased risks of cancer and other diseases. Int J Occup Environ Health. 2005;11;356-9. 2. Michaels D, Monforton C, Lurie P. Selected science: an industry campaign to undermine an OSHA hexavalent chromium standard. Environ Health: A Global Access Scientific Source, 2006;5:5. 3. Occupational Safety and Health Administration. Occupational Exposure to Hexavalent Chromium; Final Rule, February 28, Part II. Fed Reg. 2006;71:10099-385. 4. Barrow CS, Conrad JW Jr. Assessing the reliability and credibility of industry science and scientists. Environ Health Perspect. 2006;114:153-5. 5. Occupational Safety and Health Administration. Occupational Exposure to Benzene: Emergency Temporary Standards-Hearing, May 3, Part IV. Fed Reg. 1977;42:22516-22529. 6. Picciano D. Cytogenic study of workers exposed to benzene. Environ Res. 1979;19:33-8. 7. Daniel RL. Cytogenic study of workers exposed to benzene in the Texas Division of Dow Chemical U.S.A.; industrial hygiene data base. 1980. Unpublished manuscript submitted to OSHA by Venable JR, Director, U.S. Area Medical in response to request from OSHA staff. 8. Infante PF, White MC. Benzene: epidemiologic observations of leukemia by cell type and adverse health effects associated with low-level exposure. Environ Health Perspect. 1983;52:75-82. 9. Occupational Safety and Health Administration. Occupational Exposure to Benzene: Fed Reg. 1978;43:5918-80. 10. Infante PF, Biometry Section, IWSB, NIOSH, October 31, 1977. Letter inquiring about the status of the cytogenetic study results, to HC Scharnweber, Corporate Medical Director, Dow Chemical Company. 11. Infante PF, Biometry Section, IWSB, NIOSH, January 4, 1978. Letter requesting cytogenetic study results or raw data, to D Picciano, Dow Chemical USA. VOL 12/NO 3, JUL/SEP 2006 www.ijoeh.com Bias in Industry Benzene Research 271 12. Infante PF, Biometry Section, IWSB, NIOSH, January 17, 1978. Letter requesting cytogenetic study results, to E Blair, Director, Health and Environmental Research, Dow Chemical USA. 13. Scharnweber HC, Corporate Medical Director, November 22, 1977. Letter stating the Dow cytogenetic study was still in progress due to incomplete benzene exposure determination, to PF Infante, Division of Surveillance, Hazard Evaluation and Field Studies, NIOSH. 14. Picciano D, Occupational Health and Medical Research, Dow Chemical Company, January 10, 1978. Letter stating that cytogenetic study results must be cleared by E Blair of Dow Chemical, to PF Infante, Division of Surveillance, Hazard Evaluation and Field Studies, NIOSH. 15. Holder BB, Director, Biomedical Research, Dow Chemical Company, March 1, 1978. Letter transmitting results of two cytogenetic studies, to PF Infante, Biometry Section, DSHEFS, NIOSH. 16. Picciano D, Occupational Health and Medical Research, Dow Chemical Company, October 7, 1977. Internal memorandum recommending worker notification of cytogenetic study results and recommendations for medical and industrial hygiene measures to be taken, sent to BB Holder, Director, Biomedical research, Dow Chemical Company. 17. Business Week. Research that clouds the benzene issue. June 26, 1978: 42-3. 18. Occupational Safety and Health Administration. Occupational exposure to benzene: request for information, regulatory schedule. Fed Reg. 1983;48:31412-4. 19. Occupational Safety and Health Administration. Occupational exposure to benzene; proposed rule and notice of hearing, Fed Reg. 1985;50:50512-86. 20. Irons RD, Toxicologist, Chemical Industry Institute of Toxicology, May 23, 1984. Letter discussing progress of CIIT benzene cytogenetic study, to P Infante, Director, Office of Standards Review, OSHA. 21. Infante PF, Director, Office of Standards Review, OSHA, November 9, 1984. Letter requesting cytogenetic study results, to AD Kligerman, Chemical Industry Institute of Toxicology. 22. Neal RA, President, Chemical Industry Institute of Toxicology, November 14, 1984. Letter stating that slides for the rat portion of cytogenetic study are currently being reviewed, to PF Infante, Director, Office of Standards review, OSHA. 23. Vance RL, Director, Health Standards Program, OSHA, Feb 5, 1985. Letter stating that OSHA has been informed by EPA that the CIIT benzene cytogenetic study demonstrates dose-related effects at 1 ppm and requesting the results from CIIT, to RA Neal, President, Chemical Industry Institute of Toxicology. 24. Neal RA, President, Chemical Industry Institute of Toxicology, February 13, 1985. Letter stating the reading of the slides related to cytogenetic findings in rats have just been completed, to RL Vance, Director, Health Standards Program, OSHA. 25. Neal RA, Director, Chemical Industry Institute of Toxicology, June 7, 1985. Letter transmitting CIIT cytogenetic study results, to RL Vance, Director, Health Standards Programs, OSHA. 26. Durham Morning Herald. Park lab denies delaying results of benzene tests. June 6, 1985. 27. Kover FD, Chief, Chemical Screening Branch, EPA, February 6, 1985. Letter stating EPA has been informed of adverse cytogenetic effects in rats exposed to 1 ppm benzene and higher in the CIIT study, to PF Infante, Director, Office of Standards Review, OSHA. 28. Kusnetz HL, Manager, Safety and Industrial Hygiene, Shell Oil Company, July 28, 1983. Letter transmitting initial mortality study results of Wood River and Deer Park facilities, to T Auchter, Director, OSHA. 29. Austin WB, Phillips CF. Development and implementation of a health surveillance system. Am Indust Hyg Assoc J. 1983;44:63842. 30. Infante PF, Director, Office of Standards Review, OSHA, Janu- ary 27, 1984. Letter requesting data for blood abnormalities among benzene exposed workers, to Howard L. Kusnetz, Manager, Safety and Industrial Hygiene, Shell Oil Company. 31. Infante PF, Director, Office of Standards Review, OSHA, February 22, 1984. Letter requesting data for blood abnormalities among benzene-exposed workers, to RE Joyner, Director, Corporate Medical Department, Shell Oil Company. 32. Joyner RE, Director, Corporate Medical Department, Shell Oil Company, February 13, 1984. Letter stating no employee meeting benzene exposure criteria had a blood abnormality, to PF Infante, Director, Office of Standards Review, OSHA. 33. Joyner RE, Director, Corporate Medical Department, Shell Oil Company, March 5, 1984. Letter asking OSHA to redefine its criteria in requesting data related to blood abnormalities, to PF Infante, Director, Office of Standards Review, OSHA. 34. Kusnetz HL, Manager, Safety and Industrial Hygiene, Shell Oil Company, March 5, 1984. Letter asking OSHA Director to alleviate Shell Oil Company from benzene data requests by Dr. Infante, to T Auchter, Director, OSHA. 35. Infante PF, Director, Office of Standards Review, OSHA. April 17, 1984. Letter requesting data for blood abnormalities among benzene-exposed workers, to RE Joyner and HL Kusnetz, Corporate Medical Department, Shell Oil Company. 36. Joyner RE, Kusnetz HL, Corporate Medical Director and Manager, Safety and Industrial Hygiene, Shell Oil Company, May 17, 1984. Letter providing data for Shell benzene-exposed workers with blood abnormalities, to PF Infante, Director, Office of Standards Review, OSHA. 37. Kusnetz HL. President's Page; August Potpourri. Am Indust Hyg Assoc J. 1985;46:A-4. 38. Rinsky RA, Smith AB, Hornung R, et al. Benzene and leukemia: an epidemiologic risk assessment. N Engl J Med. 1987;316:104450. 39. Occupational Safety and Health Administration. Occupational Exposure to Benzene: Final Rule, September 11, Part II. Fed Reg. 1987;52:34460-578. 40. Hayes RB, Yin SN, Dosemeci M, Li GL, Wacholder S, Travis LB, et al. Benzene and the dose-related incidence of hematologic neoplasms in China. Chinese Academy of Preventive Medicine--National Cancer Institute Benzene Study Group. J Natl Cancer Inst. 1997;89,1065-71. 41. Lan Q, Zhang L, Li G, et al. Hematotoxicity in workers exposed to low levels of benzene. Science. 2004;306:1774-6. 42. Qu Q, Shore R, Li G, et al. Hematological changes among Chinese workers with a broad range of benzene exposures. Am J Ind Med. 2002;42:275-85. 43. Wong O. A critique of the exposure assessment in the epidemiologic study of benzene-exposed workers in China conducted by the Chinese Academy of Preventive Medicine and the US National Cancer Institute. Regul Toxicol Pharmacol. 1999;30: 259-67. 44. Budinsky RA, DeMott RP, Wernke MJ, Schell JD. An evaluation of modeled benzene exposure and dose estimates published in the ChineseNational Cancer Institute collaborative epidemiology studies. Regul Toxicol Pharmacol. 1999;30:244-58. 45. Hayes RB, Songnian Y, Dosemeci M, Linet M. Benzene and lymphohematopoietic malignancies in humans. Am J Ind Med. 2001;40:117-26. 46. Cappiello D. Oil industry funding study to contradict cancer claims. Houston Chronicle. April 29, 2005. 47. Mehlman MA, Adjunct Professor, Robert Wood Johnson School of Medicine, June 29 and 30, 2005. Letter requesting the companies that are funding the API benzene research in Shanghai to transfer the research to an independent body, to D O'Reilly, Chairman of the Board and CEO, Chevron Texaco Corp, J Hofmeister, President, Shell Oil Co, US, LE Raymond, Chairman and CEO, Exxon Mobil Chemical Co., and President and CEO, British Petroleum Co., UK. 272 Infante www.ijoeh.com INT J OCCUP ENVIRON HEALTH