The toxic chemicals acrylonitrile and methyl acrylate are carried by rail from Dublin Port through some of the city's northern and western suburbs en route for Killala, County Mayo, with empty trains running in the reverse direction. Strict safeguards are in place to minimise the risk of a spillage in the operation of chemical trains. All of these trains are subject to special operating instructions including a speed limit of 40 miles per hour, 35 miles per hour in places, and all persons concerned in the carriage of the chemicals are given special training. The tank containers in use comply with relevant International Union of Railways (UIC) specifications and the trains are operated generally in accordance with the exacting provisions of the Regulations concerning the international carriage of dangerous goods by rail promulgated under the COTIF Convention.