Estimation of the acute inhalation hazards of chemicals based on route-to-route and local endpoint extrapolation: experience from bulk maritime transport.

Data on acute lethal inhalation toxicity from animal studies are commonly required for assessing the hazards to human health of volatile, gaseous and dusty chemicals or their mixtures. The International Maritime Organisation (IMO) made the provision of acute inhalation toxicity data a mandatory requirement for the carriage of bulk liquid chemicals transported by sea in tank ships, thereby creating the need for inhalation data on many hundreds of chemicals in bulk maritime transport. Taking note of previously published proposals for estimating acute inhalation toxicity hazards for chemicals, and the paucity of measured experimental data, an extrapolation method has been developed by the Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) to partly fulfil this need. This method should be seen as a pragmatic approach to the challenge of missing measured experimental test data, with the added benefit of reducing tests in experimental animals. The method is based on a route-to-route (i.e. between-route) extrapolation of information on acute oral and/or dermal toxicity, in combination with data on the potential for irritation and/or corrosion to skin and eyes. The validation of this method was based on the individual evaluation of inhalation toxicity studies for 330 chemicals, including mixtures and many important chemical groups, for which the IMO holds public and industry-confidential data. The authors contend that this extrapolation method offers a reliable basis for hazard evaluation in the context of bulk maritime transport, and the 'GESAMP inhalation toxicity extrapolation method' has become part of the IMO regulatory system for the carriage of bulk liquids (i.e. noxious liquid substances) on board tank ships.