title: Serum 2,3,7,8-tetrachlorodibenzo-p-dioxin levels of New Zealand pesticide applicators and their implication for cancer hypotheses.
abstract: BACKGROUND
  The phenoxyherbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) has been widely used by professional pesticide applicators in New Zealand since before 1950. Epidemiologic studies of the risk of cancer and birth defects have been conducted in this group of workers, but little is known about the extent of their exposure to the 2,4,5-T contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent carcinogen in animals.
  
  
  OBJECTIVE
  The objective of this study was to determine whether the blood serum levels of TCDD in a group of professional 2,4,5-T applicators in New Zealand were greater than those of a matched control group not involved in 2,4,5-T spraying.
  
  
  METHODS
  Of 548 men employed as professional pesticide applicators in New Zealand from 1979 through 1982, nine were selected who had sprayed pesticides, although not necessarily 2,4,5-T, for at least 180 months. These applicators had sprayed 2,4,5-T for a range of 83-372 months. We measured the blood serum levels of polychlorinated dibenzo-p-dioxins and dibenzofurans, which were substituted with chlorine at the 2,3,7,8 position, in the nine pesticide applicators and in a matched group of nine control subjects.
  
  
  RESULTS
  The average serum level of TCDD for applicators was almost 10 times that for the matched control subjects, while the average levels of all other congeners and isomers measured in the two groups did not differ substantially. TCDD levels in eight of the nine applicators were higher than those in the control subjects (mean difference, 47.7 parts per trilion). The variation in TCDD levels among the applicators was related to their duration of work exposure to 2,4,5-T.
  
  
  CONCLUSIONS
  On the basis of our findings in these subjects in New Zealand, we conclude that increased risks of cancer from brief exposure to phenoxyherbicides reported in other countries are probably not attributable to the TCDD that contaminates 2,4,5-T. We cannot determine from these results, however, whether TCDD exposure from prolonged use of 2,4,5-T poses significant health risks.
authors.affiliation: School of Public Health, Department of Biomedical and Environmental Health Sciences, University of California, Berkeley 94720.
authors.forename: A H
authors.initials: AH
authors.lastname: Smith
authors.forename: D G
authors.initials: DG
authors.lastname: Patterson
authors.forename: M L
authors.initials: ML
authors.lastname: Warner
authors.forename: R
authors.initials: R
authors.lastname: MacKenzie
authors.forename: L L
authors.initials: LL
authors.lastname: Needham
mesh_terms: D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D009790:Occupations; D000072317:Polychlorinated Dibenzodioxins / Q000097:blood*; D012509:Sarcoma / Q000139:chemically induced; D012983:Soft Tissue Neoplasms / Q000139:chemically induced
chemical_list: D000072317:Polychlorinated Dibenzodioxins