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Changes in lymphocyte subsets in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
  1. Fatemeh Saberi Hosnijeh1,2,
  2. Virissa Lenters1,
  3. Daisy Boers1,
  4. Lützen Portengen1,
  5. Ellen Baeten3,
  6. H Bas Bueno-de-Mesquita4,5,
  7. Dick JJ Heederik1,6,
  8. Andries C Bloem3,
  9. Roel Vermeulen1,6
  1. 1Division of Environmental Epidemiology, Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, The Netherlands
  2. 2Zanjan University of Medical Science, Zanjan, Iran
  3. 3Department of Medical Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
  4. 4National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
  5. 5Department of Gastroenterology and Hepatology, University Medical Center Utrecht (UMCU), Utrecht, The Netherlands
  6. 6Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
  1. Correspondence to Dr Roel Vermeulen, Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Jenalaan 18D, PO Box 80178, Utrecht 3508 TD, The Netherlands; R.C.H.Vermeulen{at}


Objectives 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is known to have toxic effects on the haematopoietic system in animals but epidemiological studies in humans have shown inconsistent results. In this cross-sectional study we investigated changes in peripheral blood cell counts and lymphocyte subsets among workers from a Dutch historical cohort occupationally exposed to chlorophenoxy herbicides and contaminants including TCDD.

Methods Forty-seven workers who had been exposed to high levels of TCDD in the past and 38 low-exposed workers were included in the current investigation. Complete blood counts and differential and major lymphocyte subsets were analysed. Current plasma levels of TCDD (TCDDcurrent) were determined by high-resolution gas chromatography/isotope-dilution high resolution mass spectrometry. TCDD blood levels at the time of last exposure (TCDDmax) were estimated using a one-compartment first order kinetic model.

Results Cell counts and lymphocyte subsets were similar between high- and low-exposed workers, except for a non-dose dependent increase in CD4/CD8 ratio among high-exposed workers. Interestingly, most lymphocyte subsets, in particular the B cell compartment, showed a decrease with increasing levels of both TCDDcurrent and TCDDmax.

Conclusions Overall, our study showed that plasma TCDD levels had no effect on white blood cell counts and major subsets. However, a non-significant decrease in most lymphocyte subsets was noted, with the strongest effect for B cells. The latter finding may suggest that dioxin exposure might have an adverse impact on the haematopoietic system and lends some support to B cell lymphoma induction by dioxin.

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