The effect of chronic exposure to formaldehyde, phenol and organic chlorohydrocarbons on peripheral blood cells and the immune system in humans.

The aim of this study was to evaluate immunological, hematological and biochemical parameters in subjects chronically exposed to inhaled formaldehyde (F), phenol (Ph) and isomers of organic chlorohydrocarbons (Chc) released from Ksylamit. Twenty-two office workers had been exposed for 6 months to vapors of Ksylamit, used for protection of felt plates inside the office building. The concentration of Ksylamit vapor was measured at the end of the 6-month period and the level of Ph and F in the air inside the building was 1.3 mg/m3 and 0.8 mg/m3, respectively. Most of the workers had ailments due to the irritant effect of inhaled Ksylamit, but no remarkable increase in morbidity was found during the 6 months of exposure and in a 3-year follow-up. Morphological parameters of blood and the number of natural killer (NK) cells in the group of exposed subjects were within the range observed in healthy subjects matched for age and sex. The number of T-lymphocytes and NK cell cytotoxicity were significantly decreased. Phytohemagglutinin (PHA)- and alloantigen-induced lymphocyte proliferation was diminished. Some biochemical parameters suggested liver damage, although these parameters did not correlate with the levels of Ph and methanol excreted in the urine. Eight subjects with the highest levels of Ph in the urine had decreased erythrocyte and T-helper lymphocyte numbers, and increased numbers of eosinophils and monocytes. The results obtained prove that the functions of both the immune and hematopoietic systems could be affected by chronic exposure to these toxic substances.