Ethylene dibromide and inorganic bromide residues in oranges after fumigation and storage

Abstract

Levels of residues of ethylene dibromide (EDB) and inorganic bromide were measured in oranges that had been fumigated by a new EDB fumigation schedule, for the control of Queensland fruit fly. This schedule is based on 24 g EDB m-3 at 20¦C for 2 hours. The fumigation was conducted in 0.28 m3 chambers with 40% loading. After fumigation the fruit was held at the fumigation temperature for 24 hours then stored at 6¦C for a further 27 days to simulate export conditions. EDB residues in excess of the 0.5 ¦g g-1 Australian NHMRC limit were recorded during the first 14 days, but by 28 days no EDB residues were detected. Inorganic bromide residues were well below the 30 ¦g g-1 NHMRC and Codex limits but after 28 days they approached, and occasionally exceeded the 10¦g g-1 USFDA limit. Fruit that is held at ambient temperatures for 24 hours and then exported at lowered temperatures should have acceptable EDB levels after two weeks although inorganic bromide levels could exceed some overseas tolerances.