IMMUNOLOGICAL MARKERS AMONG WORKERS EXPOSED TO 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN

Objectives-To examine the association of immune cell Plumber and funct ion with occupational, exposure to substances contaminated with 2,3,7, 8- tetrachlorodibernzo-p-dioxin (TCDD). Methods-A cross sectional medi cal survey. The exposed participants were employed at two chemical pla nts between 1951 and 1972 in the manufacture of 2,4,5-trichlorophenate and its derivatives. The reference group consisted of people with no occupational exposure to phenoxy herbicides who lived within the commu nities of the workers. Data from a total of 259 workers and 243 unexpo sed referents were included in the analysis of immune function. Labora tory tests for immune status included enumeration of circulating leuko cyte and lymphocyte populations, proliferative responses of circulatin g lymphocytes to mitogens and antigens, and serum concentrations of th e major immunoglobulins and complement factor C3. Results-The workers had substantial exposure to substances contaminated with TCDD, as indi cated by a lipid adjusted mean serum TCDD concentration of 229 gpt com pared with a mean of 6 ppt in the unexposed referents. Workers were di vided into categories based on their serum TCDD concentration. For all categories except the lowest, with values of serum TCDD comparable wi th the unexposed referents, there mere increased odds of having lower counts of CD26, cells (activated T cells) (odds ratio (OR) 1.0, 95% co nfidence interval (95% Cl) 0.5 to 1.8 for TCDD <20 ppt; OR 1.6, 95% Cl 0.8 to 3.2 for TCDD 20-51 ppt; OR 2.7, 95% CP 1.4 to 5.1 for TCDD 52- 125 ppt; OR 2.6, 95% CI 1.4 to 4.9 for TCDD 125-297 ppt; OR 2.4, 95% C I 1.3 to 4.6 for TCDD 298-3389 ppt). A less consistent finding was dec reased spontaneous proliferation of cultured lymphocytes. However, inc reases were found in proliferation of lymphocytes in response to conca navalin and pokeweed in workers in the high TCDD category. Age, cigare tte smoking, and alcohol were significant predictors of several immuno logical outcomes. Conclusions-Associations between serum TCDD concentr ation and both a decrease inn circulating CD26 cells and decreased spo ntaneous background proliferation were the major findings of this stud y. These results are unlikely to be of clinical importance but may ref lect limited evidence for an association between immunological changes in workers and high serum concentrations of TCDD, or chance findings resulting from the evaluation of multiple immunological variables.