title: Changes in lymphocyte subsets in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
abstract: OBJECTIVE
  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 (TCDD(current)) were determined by high-resolution gas chromatography/isotope-dilution high resolution mass spectrometry. TCDD blood levels at the time of last exposure (TCDD(max)) 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 TCDD(current) and TCDD(max).
  
  
  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.
authors: Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Jenalaan 18D, P.O. Box 80178, Utrecht 3508 TD, The Netherlands. R.C.H.Vermeulen@uu.nl
authors: Fatemeh
authors: F
authors: Saberi Hosnijeh
authors: Virissa
authors: V
authors: Lenters
authors: Daisy
authors: D
authors: Boers
authors: Lützen
authors: L
authors: Portengen
authors: Ellen
authors: E
authors: Baeten
authors: H Bas
authors: HB
authors: Bueno-de-Mesquita
authors: Dick Jj
authors: DJ
authors: Heederik
authors: Andries C
authors: AC
authors: Bloem
authors: Roel
authors: R
authors: Vermeulen
mesh_terms: D000368:Aged; D001402:B-Lymphocytes / Q000187:drug effects*; D001772:Blood Cell Count; D016516:CD4-CD8 Ratio; D002617:Chemical Industry; D003430:Cross-Sectional Studies; D004785:Environmental Pollutants / Q000009:adverse effects*; D006540:Herbicides / Q000009:adverse effects*; D006801:Humans; D016131:Lymphocyte Subsets / Q000187:drug effects*; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced*; D016273:Occupational Exposure / Q000009:adverse effects*; D000072317:Polychlorinated Dibenzodioxins / Q000009:adverse effects*
chemical_list: D004785:Environmental Pollutants; D006540:Herbicides; D000072317:Polychlorinated Dibenzodioxins