Microbial toxins, moisture damage and asthma

Background : Toxic secondary microbial metabolites may contribute to the adverse respiratory effects of mold and moisture damage. Aims : To comprehensively characterize the presence of microbial metabolites in residential floor dust and study associations with moisture damage and the respiratory symptoms. Methods : Vacuumed living room floor dust samples from 95 homes of the LUKAS2 birth cohort were analyzed using LC-MS/MS validated for the detection of 330 microbial metabolites. Houses were inspected by civil engineer at early age: 14 out of 95 had major moisture/mold damage in living room or kitchen. At age 6 years, 14 children had developed doctor diagnosed asthma/repeated asthmatic bronchitis. Results : In total, 42 different secondary metabolites were detected, although at low levels (ng/g). Up to 29 metabolites were detected in one house, 17 on average. Six of the metabolites were present in all houses. Neither sum of concentrations nor total number of metabolites were associated with moisture/mold damage or risk of doctor diagnosed asthma/asthmatic bronchitis. There was a suggestion (p<0.2) that the presence of 10 different metabolites were positively and 1 negatively associated with moisture/mold damage, although most lacked dose-response. In unadjusted analyses, 2 metabolites were positively and 2 negatively associated (p<0.2) with the risk of asthma/asthmatic bronchitis. Conclusions : Toxic fungal metabolites are ubiquitously present in residential floor dust even without any signs of moisture/mold damage. High overall levels of toxic metabolites in house dust appeared to be a poor indicator of the severity and potential respiratory health hazard of mold/moisture damage, while the role of specific metabolites remains to be confirmed.