Effect of electrostatic charge on the contamination of plastic food containers by airborne bacterial spores.

Electrostatic charge of approximately -10 kv was produced by friction on polystyrene food container samples. This charge quickly decayed to a lower, more stable, level. Exposure of samples to positively charged red and negatively charged green fluorescent particles resulted in a particle-distribution pattern on the plastic surface. The dynamic attraction of fluorescent particles was illustrated by time-lapse photography. Similar distribution patterns of airborne bacterial spores were shown to develop. In controlled bacterial aerosol exposure tests, an increase in surface contamination of the plastic samples was found to be quantitatively related to an increase in negative electrostatic charge on the plastic. Static charge was found to accumulate on plastic food containers during their manufacture, and to remain indefinitely on many of the finished products. This charge was of the intensity and polarity to attract positively charged bacterial cells if such particles were present in the air.