The industrial solvent trichloroethylene (TCE) may cause immune system changes in workers exposed to the chemical, Italian researchers conclude.

The study found that workers exposed to TCE showed significant changes in the normal balance of immune system regulators called cytokines. The finding could explain previous research that found that workers exposed to TCE had increased rates of autoimmune disorders.

TCE is a solvent and degreaser widely used to clean metal parts.

The study included 35 printing plant workers exposed to TCE through degreasing processes, 30 plant workers without direct exposure to TCE and 40 unexposed office workers. The findings are reported in the May issue of the Journal of Occupational and Environmental Medicine.

Workers exposed to TCE had higher than average levels of a TCE metabolite in their urine compared with nonexposed workers, the researchers report.

The TCE-exposed workers also showed significant changes in the normal balance of cytokines. They had higher than normal levels of type 1 cytokines and reduced levels of type 2 cytokines.

Normally, there is a balance between type 1 and type 2 cytokines. Elevated levels of type 1 cytokines can lead to the development of autoimmune disorders, in which the immune system attacks the body's own tissues.

The researchers, led by Dr. Ivo Iavicoli of Catholic University of the Sacred Heart, Rome, stressed that their research doesn't prove that on-the-job exposure to TCE causes autoimmune disorders. However, it does offer strong evidence that relatively low-level TCE exposure can alter the immune system in specific ways.

More research is required to clarify exactly how TCE affects the immune system and the possible health effects, the study authors said.