15 { 
several major, oil spills occur every year. For example, in the first half 
of 1973 the Coast Guard reported 800 oil spills in the mid-Atlantic 
region alone, ranging from one gallon to 450,000 gallons, and ex- 
pected there to be 12,000 oil spills nationwide in 1973. The Coast 
Guard classifies a spill over 10,000 gallons in coastal areas and over 
1,000 gallons in inland waters as ‘‘major.”’ Public awareness of the 
scope of ocean pollution was further heightened when Thor Heyerdal 
was quoted in the New York Times, saying there is “‘a continuous 
stretch of at least 1400 miles of open Atlantic polluted by floating 
lumps of solidified asphalt-like oil.”” Previously most public concern 
focused on specific spills or local oil pollution disaster areas such as 
resulted from the Torrey Canyon accident or the Santa Barbara 
Channel blowout. 
Petroleum is essential to the world economy. Of the total tonnage 
of all commodities moving by sea in world trade, petroleum represents 
nearly 70 percent. More than 1300 million tons of crude oil and oil 
products are transported by sea each year and even loss of a small 
fraction of this could have a serious impact on marine environments. 
Some petroleum seeps into the oceans naturally. Two natural seeps 
have long been known off southern California and seven are charted _ 
in. the Gulf of Mexico. Natural seeps may represent a significant 
amount of the total amount of petroleum entering the marine environ- 
ment (Table X). It has been estimated that 50 to 100 times as much oil 
has been lost to the environment through natural seeps as now exists in 
reservoirs. Pollution from offshore drilling is estimated to amount to 
less than 4 percent of the amount entering the sea by ship operations. 
One of the largest and most difficult to estimate losses to the sea 
annually is from vaporization of petroleum products during their use 
or transport and subsequent .precipitation at sea. Another major 
source of petroleum contamination in the oceans is from sewage 
effluent and surface runoff. One study of New York City sewer water 
found oil and grease concentrations from 9 to 53 ppm in dry weather 
and up to 9,000 ppm in wet weather periods.”° 
Marine plants and animals also produce hydrocarbons, but generally 
these differ from petroleum hydrocarbons in some important respects. 
Some petroleum hydrocarbon compounds, especially those of low 
molecular weight, are toxic to marine ecosystems. Marine organisms 
do, however, incorporate petroleum hydrocarbons into their systems. 
This has some beneficial effect in providing a slow, gradual clean up 
of an oil spill, but it has the associated short term problem of incorpora- 
tion of petroleum hydrocarbons into the food chain. 
However, there is no evidence to date of food-web magnification of 
petroleum comparable to that observed with DDT. The ultimate 
consequences of petroleum uptake are not yet known. Fish retain 
petroleum compounds in their fatty tissues but metabolize most of 
them within two weeks. Taste tainting has already been a problem to 
the shellfish industry. Very small concentrations of petroleum hydro- 
carbons, in the order of 10 ppb, can produce this effect in filter feeders. 
Sub-lethal amounts of oil pollutants can, over a period of time, 
annihilate a species by disturbing its ability to reproduce. As little as 
10 to 100 ppb of petroleum components has been found to disrupt the 
2 Environmental Protection Agency. Combined sewer overflow study for the Hudson River Conference. 
EPA-R2-73-152, January, 1973: 287 p. 
