Didecyldimethylammonium chloride (
DDAC), an
antimicrobial agent, has been reported to induce pulmonary toxicity in animal studies.
DDAC is frequently used in spray-form household products in combination with
ethylene glycol (EG). The purpose of this study was to evaluate the toxic interaction between
DDAC and EG in the lung.
DDAC at a sub-toxic dose (100 μg/kg
body weight) was mixed with a non-toxic dose of EG (100 or 200 μg/kg
body weight), and was administrated to rats via intratracheal instillation.
Lactate dehydrogenase activity and total
protein content in the bronchoalveolar lavage fluid (BALF) were not changed by singly treated
DDAC or EG, but significantly enhanced at 1 d
after treatment with the mixture, with the effect dependent on the dose of EG. Total cell count in BALF was largely increased and polymorphonuclear leukocytes were predominantly recruited to the lung in rats administrated with the mixture. Inflammatory
cytokines,
tumor necrosis factor-alpha and
interleukin-6 also appeared to be increased by the mixture of
DDAC and EG (200 μg/kg
body weight) at 1 d post-exposure, which might be associated with the increase in inflammatory cells in lung. BALF
protein content and inflammatory cell recruitment in the lung still remained elevated at 7 d after the administration of
DDAC with the higher dose of EG. These results suggest that the combination of
DDAC and EG can synergistically induce pulmonary cytotoxicity and
inflammation, and EG appears to amplify the harmful effects of
DDAC on the lung. Therefore pulmonary exposure to these two chemicals commonly found in commercial products can be a potential hazard to human health.