title: A nested case-control study of non-Hodgkin lymphoma and serum organochlorine residues.
abstract: BACKGROUND
  The steady worldwide increase in the incidence of non-Hodgkin lymphoma during the past few decades remains mostly unexplained. Several studies suggest that there may be an association between the agricultural use of the organochlorine 1,1,1-trichloro-2,2'bis(p-chlorophenyl)ethane (DDT) and increased risk of non-Hodgkin lymphoma. We have investigated the association between risk of non-Hodgkin lymphoma and body burden of selected organochlorines in the general population in a nested case-control study.
  
  
  METHODS
  We measured prediagnostic serum concentrations of DDT, its metabolites, and other organochlorines, including polychlorinated biphenyls (PCBs), in 74 cases of non-Hodgkin lymphoma and 147 matched controls identified from a prospective cohort of 25,802 adults, established in 1974 in Washington County, Maryland, USA. We report results for total lipid-corrected serum concentrations of DDT and total PCBs.
  
  
  RESULTS
  There was a strong dose-response relation between quartiles of total lipid-corrected serum PCB concentrations and risk of non-Hodgkin lymphoma overall (odds ratios by quartile: 1.0; 1.3 [95% CI 0.5-3.3]; 2.8 [1.1-7.6]); and 4.5 [1.7-12.0]; p for trend = 0.0008) and separately in men and in women. There was also evidence suggesting that seropositivity for the Epstein-Barr virus early antigen potentiated the effects of serum PCBs. By contrast, total lipid-corrected serum concentrations of DDT were not associated with risk of non-Hodgkin lymphoma.
  
  
  CONCLUSIONS
  These results should be regarded as hypothesis-generating. Before causal inferences can be made about exposure to PCBs and increased risk of non-Hodgkin lymphoma, our findings require replication and the biological plausibility of the association needs further investigation.
authors.affiliation: Division of Cancer Edidemiology and Genetics (EPN 418), National Cancer Institute, Bethesda, MD 20892, USA.
authors.forename: N
authors.initials: N
authors.lastname: Rothman
authors.forename: K P
authors.initials: KP
authors.lastname: Cantor
authors.forename: A
authors.initials: A
authors.lastname: Blair
authors.forename: D
authors.initials: D
authors.lastname: Bush
authors.forename: J W
authors.initials: JW
authors.lastname: Brock
authors.forename: K
authors.initials: K
authors.lastname: Helzlsouer
authors.forename: S H
authors.initials: SH
authors.lastname: Zahm
authors.forename: L L
authors.initials: LL
authors.lastname: Needham
authors.forename: G R
authors.initials: GR
authors.lastname: Pearson
authors.forename: R N
authors.initials: RN
authors.lastname: Hoover
authors.forename: G W
authors.initials: GW
authors.lastname: Comstock
authors.forename: P T
authors.initials: PT
authors.lastname: Strickland
mesh_terms: D000328:Adult; D001822:Body Burden; D016022:Case-Control Studies; D003634:DDT / Q000009:adverse effects / Q000097:blood; D005260:Female; D006566:Herpesviridae Infections / Q000150:complications; D004854:Herpesvirus 4, Human / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D007306:Insecticides / Q000009:adverse effects / Q000097:blood*; D008228:Lymphoma, Non-Hodgkin / Q000097:blood* / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008396:Maryland / Q000453:epidemiology; D008875:Middle Aged; D012042:Registries; D014412:Tumor Virus Infections / Q000150:complications
chemical_list: D007306:Insecticides; D003634:DDT