Specific antibodies against methyltetrahydrophthalic anhydride and risk factors for sensitization in occupationally exposed subjects.

OBJECTIVES

Occupational exposure to methyltetrahydrophthalic anhydride (MTHPA) from an epoxy resin was studied to evaluate the nature of reported ocular and nasal complaints and some risk factors for sensitization.

METHODS

Seventy-three current and 22 former workers underwent a questionnaire survey and serologic investigations. Total and MTHPA-specific immunoglobulin (Ig)E levels were measured by means of a Pharmacia CAP system, and MTHPA-specific immunoglobulin (Ig)E levels were measured by enzyme immunoassay.

RESULTS

Forty-six (63%) of the currently exposed workers has positive MTHPA-specific IgE, and no significant difference was found between those continuously or intermittently exposed (58% and 71%, respectively). Work-related ocular or nasal symptoms were significantly associated with specific IgE but not with specific IgG4. This finding indicates that there is an IgE-mediated mechanism in most cases of work-related symptoms associated with MTHPA exposure. The total IgE levels were significantly (P < 0.005) higher in the specific IgE-positive workers than in the specific IgE-negative workers (geometric mean 101 IU/ml and 44.8 IU/ml, respectively). Multiple logistic regression analysis also revealed that the group with high total IgE levels (> or = 80 IU/ml) had a significant relative risk (RR 4.7) of producing MTHPA-specific IgE as compared with the group with low total IgE levels (< 80 IU/ml).

CONCLUSIONS

These results show that MTHPA has a high sensitizing ability and that a high total IgE level is the most significant risk factor for workers exposed to MTHPA. However, to evaluate conclusively the effect of high total IgE levels on sensitization, further prospective studies are necessary.