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Mortality in New Zealand workers exposed to phenoxy herbicides and dioxins
  1. A ’t Mannetje1,
  2. D McLean1,
  3. S Cheng1,
  4. P Boffetta2,
  5. D Colin2,
  6. N Pearce1
  1. 1Centre for Public Health Research, Research School of Public Health, Massey University, Wellington Campus, New Zealand
  2. 2International Agency for Research on Cancer, Unit of Environmental Cancer Epidemiology, Lyon, France
  1. Correspondence to:
 Dr A ’t Mannetje
 Centre for Public Health Research, Research School of Public Health, Massey University Wellington Campus, PO Box 756, Wellington, New Zealand;


Aims: To evaluate mortality in New Zealand phenoxy herbicide producers and sprayers exposed to dioxins.

Methods: Phenoxy herbicide producers (n = 1025) and sprayers (n = 703) were followed up from 1 January 1969 and 1 January 1973 respectively to 31 December 2000. A total of 813 producers and 699 sprayers were classified as exposed to dioxin and phenoxy herbicides. Standardised mortality ratios (SMR) were calculated using national mortality rates.

Results: At the end of follow up, 164 producers and 91 sprayers had died. Cancer mortality was reduced for sprayers (SMR = 0.82, 95% CI 0.57 to 1.14) and increased in exposed production workers (SMR = 1.24, 95% CI 0.90 to 1.67), especially for synthesis workers (SMR = 1.69), formulation and lab workers (SMR = 1.64), and maintenance/waste treatment/cleaning workers (SMR = 1.46). Lymphohaematopoietic cancer mortality was increased in exposed production workers (SMR = 1.65, 95% CI 0.53 to 3.85), especially for multiple myeloma (SMR = 5.51, 95% CI 1.14 to 16.1). Among sprayers, colon cancer (SMR = 1.94, 95% CI 0.84 to 3.83) showed increased mortality.

Conclusions: Results showed 24% non-significant excess cancer mortality in phenoxy herbicide producers, with a significant excess for multiple myeloma. Associations were stronger for those exposed to multiple agents including dioxin during production. Overall cancer mortality was not increased for producers and sprayers mainly handling final technical products, although they were likely to have been exposed to TCDD levels far higher than those currently in the general New Zealand population.

  • 2,4,5-T, 2,4,5-trichlorophenoxyacetic acid
  • CI, confidence interval
  • IARC, International Agency for Research on Cancer
  • ICD, International Classification of Diseases
  • MM, multiple myeloma
  • NHL, non-Hodgkin’s lymphoma
  • NIOSH, National Institute for Occupational Safety and Health
  • NZHIS, New Zealand Health Information Service
  • PCLTAS, personal computer life table analysis system
  • RR, rate ratio
  • SIA, small intestinal adenocarcinoma
  • SMR, standardised mortality ratio
  • TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin
  • cancer
  • cohort
  • dioxin
  • mortality
  • phenoxy herbicides

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  • Funding: The original work on the cohort was funded by the International Agency for Research on Cancer (IARC), and the further follow up was funded by the New Zealand Lottery Grant Board. The Centre for Public Health Research is supported by a Programme Grant from the Health Research Council of New Zealand. The sprayers cohort was originally based on a survey of registered chemical applicators conducted by Professor Allan Smith7 which was funded by grants from the New Zealand Department of Health, the Medical Research Council, and the War Pensions Board.