Editing Ship (section)

===Oil spills===
{{Main|Oil spill}}
[[File:OilCleanupAfterValdezSpill.jpg|thumb|right| The tanker [[Exxon Valdez oil spill|''Exxon Valdez'' spilled]] {{convert|10800000|USgal|impgal L|sigfig=4}} of oil into Alaska's [[Prince William Sound]].<ref>{{cite web|title=Frequently asked questions about the Exxon Valdez Oil Spill |url=http://www.evostc.state.ak.us/History/FAQ.htm |publisher=State of Alaska |url-status=dead |archive-url=https://web.archive.org/web/20060925163639/http://www.evostc.state.ak.us/History/FAQ.htm |archive-date=2006-09-25}}</ref>]]
Oil spills have devastating effects on the environment. Crude oil contains [[polycyclic aromatic hydrocarbons]] (PAHs) which are very difficult to clean up, and last for years in the [[sediment]] and marine environment.<ref name="Panetta" /> Marine species constantly exposed to PAHs can exhibit developmental problems, susceptibility to disease, and abnormal reproductive cycles.

By the sheer amount of oil carried, modern oil tankers must be considered something of a threat to the environment. An oil tanker can carry {{convert|2|Moilbbl|m3|sigfig=4}} of crude oil, or {{convert|84000000|USgal|impgal L|sigfig=4}}<!-- See [[Talk:ship#conversions]] -->. This is more than six times the amount spilled in the widely known [[Exxon Valdez oil spill|''Exxon Valdez'' incident]]. In this spill, the ship ran aground and dumped {{convert|10800000|USgal|impgal L|sigfig=4}} of oil into the ocean in March 1989. Despite efforts of scientists, managers, and volunteers, over 400,000 [[seabirds]], about 1,000 [[sea otters]], and immense numbers of fish were killed.<ref name="Panetta" />

The International Tanker Owners Pollution Federation has researched 9,351 accidental spills since 1974.<ref name="itopf" /> According to this study, most spills result from routine operations such as loading cargo, discharging cargo, and taking on fuel oil.<ref name="itopf" />  91% of the operational oil spills were small, resulting in less than 7&nbsp;tons per spill.<ref name="itopf" /> Spills resulting from accidents like collisions, groundings, hull failures, and explosions are much larger, with 84% of these involving losses of over 700&nbsp;tons.<ref name="itopf" />

Following the ''Exxon Valdez'' spill, the United States passed the [[Oil Pollution Act of 1990]] (OPA-90), which included a stipulation that all tankers entering its waters be [[Double-hulled tanker|double-hulled]] by 2015. Following the sinkings of ''[[Erika (tanker)|Erika]]'' (1999) and ''[[Prestige oil spill|Prestige]]'' (2002), the [[European Union]] passed its own stringent anti-pollution packages (known as Erika I, II, and III), which require all tankers entering its waters to be double-hulled by 2010. The Erika packages are controversial because they introduced the new legal concept of "serious negligence".<ref name="EuroP" />