['INBIFO', 'Institut', 'fur', 'biologische', 'Forschung', '-', 'KéIn', 'DOCUMENTATION', 'P', '0500/5061', 'MNO69RA17', '6218', 'PAGE', '1-8', ' ', 'The', 'irritative', 'effects', 'of', 'the', 'test', 'substances', 'were', 'compared', 'at', 'an', 'effect', 'level', 'of', '15', 'percent', 'decrease', 'of', 'the', 'C02', 'exhalation', 'during', 'test', 'substance', 'exposure.', 'The', 'CO2', 'response', 'at', 'this', 'level', 'is', 'consid-', 'ered', 'to', 'be', 'a', 'test', 'substance', 'dependent', 'physiological', 'effect.', 'Corresponding', 'to', 'a', 'short-time', 'evaluation,', 'where', 'the', 'C02', 'exhala-', 'tion', 'during', '5', 'to', '30', 'minutes', 'after', 'the', 'start', 'of', 'test', 'substance', 'exposure', 'was', 'compared', 'with', 'that', 'during', 'the', 'last', 'hour', 'of', 'the', 'preexposure,', 'this', 'effect', 'level', 'was', 'reached', 'approx.', 'at', 'a', 'concentra-—', 'tion', 'of', '12', 'micrograms', 'formaldehyde/liter,', '14', 'micrograms', 'acrolein/', 'liter,', '900', 'micrograms', 'ammonia/liter', 'and', '3400', 'micrograms', 'acetalde-—', 'hyde/liter', 'respectively.', 'These', 'concentrations', 'correlate', '(r', '=', '0.945)', 'with', 'the', 'RD50', 'values', 'of', 'the', 'test', 'substances', 'in', 'mice.', 'For', 'isoprene', 'the', '15', 'percent', 'effect', 'level', 'was', 'not', 'reached', 'even', 'when', 'an', 'extremely', 'high', 'isoprene', 'concentration', 'of', 'approx.', '40000', 'micrograms/liter', 'was', 'examined.', 'In', 'spite', 'of', 'toxic', 'effects', 'the', 'CO2', 'exhalation', 'of', 'the', 'isoprene-exposed', 'rats', 'was', 'scarcely', 'impaired.', 'Therefore', 'isoprene', 'is', 'characterized', 'as', 'a', 'test', 'substance', 'with', 'a', 'negligible', 'sensory', 'irritant', 'activity.', 'Regarding', 'the', 'concentration', 'causing', 'a', '15', 'percent', 'decrease', 'of', 'the', 'cO2', 'exhalation,', 'formaldehyde', 'and', 'acrolein', 'are', 'the', 'strongest', 'irritating', 'single', 'test', 'substances.', 'The', 'irritative', 'potency', 'of', 'both', 'components', 'is', 'about', 'the', 'same,', 'With', 'regard', 'to', 'the', 'irritative', 'potency', 'ammonia', 'takes', 'an', 'intermediate', 'rank', 'followed', 'by', 'acetal-', 'dehyde.', 'Ammonia', 'is', 'about', '80', 'times', 'and', 'actaldehyde', 'about', '280', 'times', 'less', 'irritative', 'than', 'formaldehyde.', 'Taking', 'into', 'account', 'the', 'different', 'concentrations', 'of', 'the', 'test', 'substances', 'in', 'SS,', 'an', 'estimation', 'of', 'the', 'irritative', 'effects', 'of', 'the', 'single', 'test', 'substances', 'and', 'the', 'mixture', 'relative', 'to', 'SS', 'based', 'on', 'concentration-response', 'relationships', 'where', 'the', 'test', 'substance', 'concentration', 'was', 'expressed', 'as', 'CO', 'concentration', 'of', 'equivalent', 'SS', '(a).', 'From', 'the', 'position', 'of', 'the', 'corresponding', 'concentration-response', ',', '(a)', 'The', 'irritative', 'effects', 'of', 'the', 'examined', 'test', 'substances', 'and', 'SS', 'were', 'compared', 'indirectly', 'because', 'the', 'results', 'were', 'obtained', 'in', '2', 'different', 'studies', 'with', 'different', 'conditions.', '3285', '669ZErSoSz']