Carbonyl sulfide (COS) as a fumigant for stored products: progress in research and commercialisation

Carbonyl sulfide (COS) is a potential new fumigant for stored products, patented worldwide by CSIRO Australia. It may replace methyl bromide for many applications on durable commodities and be used as an alternative to phosphine when there is a significant problem with insect resistance. Laboratory and field studies have shown that COS is effective on a wide range of pests at all life stages, at reasonable concentrations (<100 g/m3) and exposure times (1–5 days) at 10–25 ̊C. Quality studies indicated no adverse effects on canola oil composition or colour, quality of bread, noodles or sponge cake made from wheat, malting or brewing characteristics of barley, or germination or plumule length of wheat, oats, barley or canola. Sorption, penetration, desorption, decay of residues to natural levels, and interaction with other materials have all been shown to be consistent with being a practical fumigant for most commodities. Because COS in naturally present in a great variety of raw and processed foodstuffs, and is produced in mammals during the metabolism of some sulfur-containing compounds, it is argued that the low residues of COS remaining postfumigation do not appear to pose a risk to human health. Similarly, the widespread and abundant natural occurrence of COS in the air, soil, and live and decaying vegetation suggests that COS does not present a tangible environmental hazard. COS has been trademarked in Australia as COSMIC®, and a global licence agreement has been signed for manufacture and distribution of COS.