In-Transit Shipboard Fumigation of Corn on a Tanker Vessel

Corn aboard a tanker vessel was fumigated in transit with aluminum phosphide tablets at the rate of 1.06 g/m3 and with Detia gas bag blankets at the rate of 1.17 g/m3 Gas concentrations were always highest on the surface of the grain; however, some gas was detected at all sample points during the first half of the 44-day fumigation. The ship’s stripper pump was used to facilitate rapid penetration of phosphine in one fumigated tank, but the gas channeled downward directly to the rose box and was not uniformly distributed. To assess safety to the crew, phosphine was monitored in transit three times daily at 26 selected locations throughout the living and working areas of the ship. After fumigation, one tank was found to have a cracked bulkhead, and phosphine levels exceeding the threshold limit value were observed in an adjacent forward locker room. These concentrations dissipated quickly and completely after the locker room door was opened. Although live insects were on-loaded in the com, none were found during unloading. Phosphine residues were lowest on corn fumigated with bag blankets; residues exceeding the tolerance of 100 ppb were found on samples taken from the surface of the com in tanks treated with tablets.