Seascapes - What are the facts about oil pollution?- By BIMCO

Shipping is the most environmentally-friendly form of mechanised transport, but when the man or woman thinks of "tankers", the words "oil pollution" flash up in lights. This is hugely unjustified, for 99.9997 per cent. of all oil carried by sea is delivered safely with not a drop spilt. It is a remarkable record, with 7,000 tankers with the capacity of some 350 million tonnes at sea and the amount of oil carried rising by some 5 per cent. per annum.Even more remarkable is the fact that despite this growth, the amount of oil spills that are attributable to ships has been steeply reduced, by technical developments, good housekeeping and the avoidance of accidents. Operational pollution, which was once caused by ships washing out their tanks has been reduced to a negligible amount, modern tankers never having any need to mix water into their cargo oil tanks. It is also worth remembering that all ships - not just tankers - carry oil fuel for their own consumption, and in recent years the number of incidents involving tankers was substantially less than those where ships other than tankers spilt oil into the sea. A large containership could carry several thousand tonnes of bunker oil.
But it is also important to note that most pollution of the sea does not come from ships at all. More than 60 per cent. of the total oil that escapes into the sea comes from industrial wastes, from industry, sewage, and dumping into rivers, harbours, bays and the open sea. Shipping by contrast contributes around 7 per cent. of the total.
Accidents do happen, and it is the spectacular oil spill that is highly visual and kills sea and bird life that makes the headlines. But where oil enters the sea, the damage it causes tends to be a short term phenomenon, with the oil broken down by natural organic and chemical processes, weathering and evaporating. Oil is, after all, a natural substance, even though it is toxic to wildlife and unpleasant when it reaches the shore. Most crude oils and light or white oils cause only temporary damage to the environment. Fuel oils, on the other hand, are more difficult to treat.
Recent years have seen great efforts by the shipping industry to reduce the risk of oil pollution. Structural changes have been required of tanker owners to ensure that they have a double hull around their oil cargo compartments and all new tankers entering service are configured in this fashion, giving substantial protection in a low-impact grounding or collision that might hole a single skinned ship. Ballast tanks, which are necessary to keep the ship at an optimum draught, when no cargo is aboard are now separate from oil tanks and there is careful monitoring of any water pumped overside to ensure that there are no oil traces in it. When oil is loaded and discharged, or moved about the ship, it is done with the utmost care, with sophisticated instrumentation monitoring quantities pumped and the position of valves.A whole range of measures have been implemented by the industry to minimise the risk of pollution and to promptly compensate those affected if pollution is caused. There are heavy liabilities for polluters