Long-term effects of a cross-linked polyacrylate superabsorbent in the hamster

Male and female Syrian Golden hamsters breathed respirable (< 10 microns) cross-linked polyacrylate dust (0.3, 1.0 or 10 mg m-3) for 6 h a day, 5 days per week for 28 exposures and were then held for 42 and 46 weeks. The animals appeared healthy during and immediately following the exposure; there were no differences in body weight at any dose, nor were there any deaths. Foreign material was detected in the lungs 42 and 46 weeks post-exposure. There was a slight increase in alveolar macrophages, which appeared to be dose related, and there was a slight increase in inflammatory cells at the highest dose. There was no evidence of fibrosis in any group either 42 or 46 weeks post-exposure. The first animal (male, control) died 12 weeks post-exposure and mortality increased from 21 weeks post-exposure. The deaths were not dose related but were distributed equally across all groups and appeared to be part of the normal mortality patterns for hamsters. These results indicate that repeated exposure of Syrian Golden hamsters to low concentrations of cross-linked polyacrylate dust in particle sizes capable of reaching deep lung structures does not cause pulmonary fibrosis at a later time in the life-cycle. When combined with our earlier results, these data indicate that the test material is continuously cleared from the lung following termination of the exposure.