Rong Wang, Yawei Zhang, Qing Lan, Theodore R. Holford, Brian Leaderer, Shelia Hoar Zahm, Peter Boyle, Mustafa Dosemeci, Nathaniel Rothman, Yong Zhu, Qin Qin and Tongzhang Zheng
Correspondence to Dr. Tongzhang Zheng, Yale School of Public Health, 60 College Street, LEPH 427, P.O. Box 208034, New Haven, CT 06520-8034 (e-mail: tongzhang.zheng@yale.edu
A population-based case-control study involving 601 incident cases of non-Hodgkin lymphoma (NHL) and 717 controls was conducted in 1996–2000 among Connecticut women to examine associations with exposure to organic solvents. A job-exposure matrix was used to assess occupational exposures. Increased risk of NHL was associated with occupational exposure to chlorinated solvents (odds ratio (OR) = 1.4, 95% confidence interval (CI): 1.1, 1.8) and carbon tetrachloride (OR = 2.3, 95% CI: 1.3, 4.0). Those ever exposed to any organic solvent in work settings had a borderline increased risk of NHL (OR = 1.3, 95% CI: 1.0, 1.6); moreover, a significantly increased risk was observed for those with average probability of exposure to any organic solvent at medium-high level (OR = 1.5, 95% CI: 1.1, 1.9). A borderline increased risk was also found for ever exposure to formaldehyde (OR = 1.3, 95% CI: 1.0, 1.7) in work settings. Risk of NHL increased with increasing average intensity (P = 0.01), ...
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BooklynDodger(s) comment: So many issues, so many cell types, so little time to write coherently. This study is about hematopoietic tumors in people.
For lymphomae, there's Hodgkins Disease and non-Hodgkins Lymphoma. NHL has some subtypes. For leukemiae we have 4 kinds - acute and chronic types for myelogenous and lymphocytic. Also subtypes. There's also multiple myeloma. Each has contrasting age and gender patterns. Ultimately these tumors all come from cell lines tracking back to a common stem cell, but there's several generations of intermediate stem cells from which the tumor might arise. Logically, the stem cell is the locus of attack. Should each be considered independently, or lumped together? Does clear evidence for an assocation with one cell type identify a hazard for all the other cell types?
Finally, the picture in laboratory studies is also muddled. Benzene is the SQN agent for leukemia in people. In the bioassay, it's a very potent carcinogen, but at many tumor sites not including leukemia:
"Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity of benzene for male F344/N rats, for female F344/N rats, for male B6C3F1 mice, and for female B6C3F1 mice. For male rats, benzene caused increased incidences of Zymbal gland carcinomas, squamous cell papillomas and squamous cell carcinomas of the oral cavity, and squamous cell papillomas and squamous cell carcinomas of the skin. For female rats, benzene caused increased incidences of Zymbal gland carcinomas and squamous cell papillomas and squamous cell carcinomas of the oral cavity. For male mice, benzene caused increased incidences of Zymbal gland squamous cell carcinomas, malignant lymphomas, alveolar/bronchiolar carcinomas and alveolar/bronchiolar adenomas or carcinomas (combined), harderian gland adenomas, and squamous cell carcinomas of the preputial gland. For female mice, benzene caused increased incidences of malignant lymphomas, ovarian granulosa cell tumors, ovarian benign mixed tumors, carcinomas and carcinosarcomas of the mammary gland, alveolar/bronchiolar adenomas, alveolar/bronchiolar carcinomas, and Zymbal gland squamous cell carcinomas. Dose-related lymphocytopenia was observed for male and female F344/N rats and male and female B6C3F1 mice."
For perchloroethylene, the picture was different:
"Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenicity of tetrachloroethylene for male F344/N rats as shown by an increased incidence of mononuclear cell leukemia and uncommon renal tubular cell neoplasms. There was some evidence of carcinogenicity of tetrachloroethylene for female F344/N rats as shown by increased incidences of mononuclear cell leukemia. There was clear evidence of carcinogenicity for B6C3F1 mice as shown by increased incidences of both hepatocellular adenomas and carcinomas in males and of hepatocellular carcinomas in females."
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