THE adequacy of the US Coast Guards regulations governing oil spills will be known only after they have been tested under actual spill conditions, says a shipping executive. Mr Michael Naess, is chairman of the Petrobulk Group, said tanker owners, operators and charterers were concerned as to what would happen after August 18 when the regulations came into force. ''Most of those which have already been issued, and there are more to come, are very specific in nature,'' he said in a talk entitled US Environmental Legislation: Latest Trends for Tanker Operations at last week Intertanko's annual meeting. He suggested that the vessel response plans of tankers to oil spills would have to be modified if the US Coast Guards changed or amended their regulations after testing them under actual spill conditions. The question of whether these regulations would survive the test under actual spill conditions was a concern to the industry, he said. Mr Naess said the real teeth in the Oil Pollution Act 1990 was the liability provisions which would come into force on August 18. Even if owners, operators and charterers were satisfied with the written and workable vessel response plans to oil spills, the capability of the sub-contractors to meet such emergencies had still to be tested, he said. In the event of a spill, if they turned out to be improperly equipped and could not respond, the responsibility would remain with the owners, operators or charterers, he added. Mr Naess warned that this could result in heavy fines, or in unlimited liability and even criminal penalties.