To evaluate the hematological changes and the immunological function of children living near the petrochemical estate in Ulsan.

The study subjects comprised of 238 children who consisted of 143 children living near the petrochemical estate and 95 children living in a suburban area. We conducted the hematological examination 3 times, in April, July and October. Also we evaluated the immunological function of some children in July. To confirm differences between schools repeated measures ANOVA of generalized linear model was done controlling age and sex as covariates.

The blood cell counts of children showed differences between schools in accordance with the survey month. The total WBC, neutrophil, and lymphocyte counts of children living in a suburban area decreased in July and increased in October again, but those of some children living near the petrochemical estate did not changed distinctly. The RBC counts of children living in a suburban area decreased in July and increased in October again, but those of some children living near the petrochemical estate decreased as time passed. The changes of the amount of hemoglobin of all study subjects were similar with those of RBC. The platelet counts of all study subjects decreased in July and increased in October again. In the generalized linear model, school was a significant independent variable for the total WBC, RBC, and platelet counts, and sex was a significant independent variable for the RBC counts. Age was a significant independent variable for the lymphocyte and platelet counts. P values of all blood cell were statistically significant in interaction variable between the survey month and school, and those of the total WBC, neutrophil, and lymphocyte counts were statistically significant in interaction variable between the survey month and age. The immunological function showed no significant difference between study groups.

The total WBC and RBC counts which would be easily affected by volatile organic compounds(VOCs) in the atmosphere showed differences between schools in accordance with the survey month. This suggests that the amounts of exposure to VOCs are different among each school children in different months. To ascertain the hematological changes by VOCs, an additional study evaluating the concentrations of atmosphere of VOCs and biological monitoring of some VOCs is needed.