
Bird footprints over tarball, taken on 19 Aug 2010, Mississippi Sound (Petit Bois Island).
In research published online November 2011 in the journal EcoHealth, Auburn University microbiologist Cova Arias and colleagues discovered that Deepwater Horizon tar balls found months after the spill contained high levels of bacteria, including 10 times the level of Vibrio vulnificus as found in the surrounding sand, a finding first reported by the Associated Press. V. vulnificus is the leading cause of seafood-borne disease fatalities nationwide, and it has a fatality rate of 20 to 30 percent when it infects skin wounds.
"We don't know what the real risk is at this point," Arias told LiveScience. But to be safe, beachgoers should avoid handling the tar balls, she said.
About 4.9 million barrels of oil, or 205 million gallons, spilled from a riser pipe in the seafloor after the Deepwater Horizon rig exploded and sank in late April 2010. Some of that oil persists in the Gulf in the form of tar balls.











