Free Case Review

Benzene and Hairy Cell Leukemia

Benzene Causing Hairy Cell Leukemia Studies

Although Hairy Cell Leukemia is too rare a subtype of leukemia to fully investigate using epidemiologic methods, a few case-control studies of hairy cell leukemia patients have been performed, and some have shown significant excesses of the disease among benzene-exposed workers.

In 1985, researchers at the University of Chicago reported the results of a case-control study of 45 hairy cell leukemia patients. They found that occupational exposure to organic chemicals was significantly greater among both sexes of the cases than among their respective matched controls (RR = 3.10; 95% CI = 1.51 - 6.36). Oleske, D., et al., "A Case-Control Inquiry into the Etiology of Hairy Cell Leukemia," American J. Epidemiol. 121(5):675-683 (1985).

In 1988, investigators at the Naval Hospital in San Diego evaluated 86 civilian employees with a history of leukopenia at the Naval Weapons Center in China Lake. Although there was no evidence of myelodysplasia or cellular maturation abnormalities in the subjects, two cases of Hairy Cell Leukemia were identified. In reviewing the exposure histories of these two subjects, it was determined that both had extensive exposure to a wide variety of solvents, including benzene. Luiken, G. A., et al., "Hematologic Evaluation of Employees with Leukopenia," A.J.C.P. 90(6):679-683 (1988).

In 1995 French investigators reported the results of a case-control study of 291 hairy cell leukemia patients. They found a significant association for men with self-reported exposure to petrol (gasoline) or diesel (OR = 1.5; 95% CI 1.0 - 2.1). Clavel, J., et al., "Hairy Cell Leukaemia, Occupation, and Smoking," Brit. J. Haematol. 91:154-161 (1995). This finding suggests that benzene is a causative factor in Hairy Cell Leukemia because benzene is a gasoline additive, and has typically been found in gasoline at concentrations up to 5%.

In 1998, Swedish investigators reported the results of a case-control study of 121 male hairy cell leukemia patients. They found significantly increased risks of the disease among workers exposed to wood-impregnating agents (OR = 2.4; 95% CI = 1.3 - 4.6), and exhausts (OR = 2.2; 95% CI = 1.3 - 3.9), and non-significantly increased risks of the disease among workers exposed to solvents (OR = 1.5; 95% CI = 0.8 - 2.7). The two wood-impregnating agents to which the patients were exposed were pentachlorophenols and creosote. Risks for exposure to both agents was significantly increased: Pentachlorophenols (OR = 2.6; 95% CI = 1.1 - 6.2); Creosote (OR - 3.1; 95% CI = 1.1 - 8.6). Nordstrom, M., et al., "Occupational Exposures, Animal Exposure and Smoking as Risk Factors for Hairy Cell Leukaemia Evaluated in a Case-Control Study," Brit. J. Cancer 77(11):2048-2052 (1998).

In 1993, British investigators conducted a case-control study of 50 patients with hairy cell leukemia and 95 controls. They reported nonsignificantly increased risks of hairy cell leukemia for exposure to solvents (OR = 1.45, 95% CI = 0.58 - 3.66) petroleum products, (OR = 2.14, 95% CI = 0.92 - 5.02), and benzene (OR = 2.00, 95% CI = 0.50 - 8.00). Staines, A., et al., "Hairy Cell Leukaemia: Descriptive Epidemiology and a Case-Control Study," Br. J. Haematol. 85(4):714-717 (1993).

The foregoing studies indicate that benzene can indeed cause hairy cell leukemia. This conclusion is also supported by several case reports in the medical literature.

In 1982 Bescol-Liversac and other French investigators reported a case of benzene-induced Hairy Cell Leukemia. Bescol-Liversac, J., et al., "Un cas mixte d'intoxication benzenique professsionnelle et de leucemie a tricholeucocytes," ["A case of occupational benzene intoxication and associated hairy cell leukemia"], Toxicol. European Res. 4(6):329-335 (1982).

In 1987 Aksoy reported one case of benzene-induced Hairy Cell Leukemia along with two cases of Chronic Lymphocytic Leukemia. Aksoy, M., "Chronic lymphoid leukaemia and hairy cell leukaemia due to chronic exposure to benzene: report of three cases," Brit. J. Haematol. 66:209-211 (1987).

In response to Aksoy's paper, Scottish investigators reported another case of benzene-induced hairy cell leukemia to the British Journal of Haematology. They described a 55-year old patient diagnosed with hairy cell leukemia in 1984. At the time of diagnosis he had been a paint sprayer for more than 25 years who did not wear personal protective equipment. Because spray-painting is an occupation which involves the use of benzene-containing solvents, the investigators considered the case a likely case of benzene-induced hairy cell leukemia. Ng, J-P., et al., "Hairy Cell Leukaemia Due to Chronic Exposure to Benzene," Brit. J. Haematol. 67:116-121 (1987).

Also in 1987, French investigators reported a series of hairy cell leukemia patients with benzene exposure. They noted that a "striking finding was the frequency of occupations in contact with petroleum-derived substances." Of 105 Hairy Cell Leukemia patients who were interviewed, 21 worked as garage mechanics or drivers. Flandrin, G., et al., "Is Male Predominance (4/1) in Hairy Cell Leukaemia Related to Occupational Exposure to Ionizing Radiation, Benzene and Other Solvents?" Brit. J. Haematol. 67(1):119-120 (1987). Because automotive mechanics are typically exposed to benzene from gasoline and solvents, the investigators considered the prevalence of mechanics (20%) among the Hairy Cell Leukemia patients an indication of a benzene-related etiology of their disease.

In 1988 Polish investigators reported another case of benzene-induced hairy cell leukemia and explained the difficulties of making such a causal determination. Byczkowska Z, et al., ["Practical and disputable aspects of the effect of benzene containing organic solvents exemplified by the case of hairy cell leukemia"] [in Polish]; Med. Pr. 39(3):206 211 (1988).

Conclusion of HCL Studies

The studies described above provide sufficient data to conclude that exposure to benzene can cause Hairy Cell Leukemia (HCL) and does cause this disease in exposed workers. Indeed, in his recent review of the carcinogenicity of benzene, Professor Myron A. Mehlman, who for many years served as the Director of Toxicology of Mobil Oil Corporation, concluded: "While there is a prevalence of acute myelogenous leukemia, it is certain that all forms of leukaemia are caused by benzene exposure." Table 4 of his review article, titled "Types of leukemias and lymphomas from benzene exposure in humans," specifically lists Chronic Lymphocytic Leukemia and Hairy Cell Leukemia as types of leukemia that are caused by benzene exposure. Mehlman, M. A., "Benzene: a haematopoietic and multi-organ carcinogen at any level above zero," Eur. J. Oncol. 9(1):15-36 (2004).

Additionally, it is biologically plausible that benzene causes Hairy Cell Leukemia and all other subtypes of Chronic Lymphocytic Leukemia for at least two reasons: First, the subtypes of Chronic Lymphocytic Leukemia (including Hairy Cell Leukemia) are subtypes of one disease, CLL, inasmuch as they all derive from a genetically damaged pluripotent stem cell which can differentiate into all lymphocytic cell types and proliferate, developing the various CLL subtypes. Second, epidemiologic studies and case series show that benzene causes all types of leukemia, apparently because of its hematotoxicity and genotoxicity. Given the substantial number of studies showing that benzene causes all the different types of leukemia, it would seem illogical that of all the types of leukemia caused by benzene exposure, benzene would not cause Hairy Cell Leukemia, especially when studies have reported causal associations between benzene and CLL and HCL.

If you have hairy cell leukemia from benzene exposure, our benzene attorneys can help develop a winning case.

Our Lawyers Can Help!

If you have questions about benzene poisoning or blood disorder symptoms and are concerned about possible occupational diseases and cancers, we are here to help. Toxic tort and injury laws are complex and confusing. The Metzger Law Group is here to help you. Call us today for a FREE evaluation to find out if you have a case or fill out our free evaluation forms to consult with a member of our caring staff.