title: Occupational trichloroethylene exposure and risk of lymphatic and haematopoietic cancers: a meta-analysis.
abstract: The carcinogenic potential of trichloroethylene (TCE) continues to generate much controversy, even after the US Environmental Protection Agency raised its classification to 'carcinogenic to humans'. We conducted a meta-analysis of published cohort and case-control studies exploring occupational TCE exposure in relation to five different lymphatic and haematopoietic cancers: non-Hodgkin's lymphoma (NHL, N=24), Hodgkin's lymphoma (HL, N=13), multiple myeloma (MM, N=11), leukaemia (N=12) and chronic/small lymphocytic leukaemia (CLL/SLL, N=7).  Studies published between 1950 and 2011 were identified through a PubMed Medline search. All studies included in analyses were classified as those that assessed either occupational TCE exposure specifically ('TCE-exposure' studies) or a broader classification of all chlorinated solvents ('chlorinated solvent-exposure' studies).  A significantly raised summary estimate for NHL was seen for all cohort and case-control 'TCE-exposure' studies combined (N=19; relative risk (RR)=1.32, 95% CI 1.14 to 1.54; I(2)=25.20; p-heterogeneity=0.12) and for cohort 'TCE-exposure' studies (N=10; RR=1.52, 95% CI 1.29 to 1.79; I(2)=7.09; p-heterogeneity=0.63). A non-significant but raised summary estimate was seen for NHL case-control 'TCE-exposure' studies. No significant association with NHL risk was detected overall for any 'chlorinated solvent-exposure' studies. Summary estimates for occupational TCE exposure were not associated with risk of HL, MM, leukaemia or CLL/SLL.  Our updated meta-analysis of NHL, which incorporates new analytical results from three cohort and four case-control studies, supports an association between occupational TCE exposure and NHL.
authors.affiliation: Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20852, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Karami
authors.forename: Bryan
authors.initials: B
authors.lastname: Bassig
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Stewart
authors.forename: Kyoung-Mu
authors.initials: KM
authors.lastname: Lee
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Rothman
authors.forename: Lee E
authors.initials: LE
authors.lastname: Moore
authors.forename: Qing
authors.initials: Q
authors.lastname: Lan
mesh_terms: D002273:Carcinogens; D006689:Hodgkin Disease / Q000209:etiology; D006801:Humans; D007938:Leukemia / Q000209:etiology; D008228:Lymphoma, Non-Hodgkin / Q000209:etiology*; D009101:Multiple Myeloma / Q000209:etiology; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D012997:Solvents / Q000633:toxicity*; D014241:Trichloroethylene / Q000633:toxicity*
chemical_list: D002273:Carcinogens; D012997:Solvents; D014241:Trichloroethylene