Our friends at the UK P&I Club have issued a warning about improperly declared shipments of thiourea dioxide, predominantly emanating from China.

Thiourea dioxide (or formamidine sulphinic acid) is an odourless white to pale yellow crystalline powder. It is used in the paper and textile industry as a bleaching and reducing agent and is listed under UN No. 3341 in class 4.2 of the IMDG code. It is normally packed in sealed drums since it readily oxidises in air and may generate enough heat to cause ignition when in contact with moisture. The cargo may only be stowed on deck.

According to the UK Club, there have been several instances recently of shippers naming the product as "Thiourea D" or "Thiourea De" and claiming that it is stable. One such shipment decomposed violently in a container, producing sulphur dioxide that contaminated neighbouring containers and necessitating expensive decontamination, clean-up and disposal operations. Subsequent chemical analysis confirmed that the cargo was, indeed, thiourea dioxide.

The Club warns that neither "Thiourea D" nor "Thiourea De" is a recognised shipping name. If any cargoes with these or similar descriptions are offered to members, even if the shippers claim that they are not hazardous, they should be refused.