PRIORITIZING TESTING OF ORGANIC-COMPOUNDS DETECTED AS GAS-PHASE AIR-POLLUTANTS - STRUCTURE-ACTIVITY STUDY FOR HUMAN CONTACT ALLERGENS

Organic compounds that are used or generated anthropogenically in larg e quantities in cities can be identified through their presence in the urban atmosphere and in air pollutant source emissions. Compounds ide ntified by this method were screened to evaluate their potential to ac t as contact allergens. The CASE and MULTICASE computer programs, whic h are based on the detection of structure-activity relationships (SAR) , were used to evaluate this potential. These relationships first are determined by comparing chemical structures to biological activity wit hin a learning set comprised of 458 compounds, each of which had been tested experimentally in human trials for its sensitization potential. Using the information contained in this learning set, CASE and MULTIC ASE predicted the activity of 238 compounds found in the atmosphere fo r their ability to act as contact allergens. The analysis finds that 2 1 of 238 compounds are predicted to be active contact allergens (proba bility >0.5), with potencies ranging from mild to very strong. The com pounds come from chemical classes that include chlorinated aromatics a nd chlorinated hydrocarbons, N-containing compounds, phenols, alkenes, and an S-containing compound. Using the measured airborne concentrati ons or emission rates of these compounds as an indication of the exten t of their use, together with their predicted potencies, provides an e fficient method to prioritize the experimental assessment of contact s ensitization of untested organic compounds that can be detected as air pollutants.