By DOTTY NIST
A year after the BP Deepwater Horizon oil spill, updates from officials on the safety of gulf beaches and seafood are encouraging, but it is evident that the public still has questions about the matter.
Results from reports on oil and dispersant impacts of the oil spill were presented at the Destin City Hall Annex on March 29, with approximately 70 community members in attendance.
Gary Petrae of the National Oceanic and Atmospheric Administration (NOAA) provided a summary of sampling and monitoring activities and findings by the Operational Science Advisory Team (OSAT). Composed of representatives and members of various agencies, OSAT was an advisory board created by the U.S. Coast Guard and enlisted to assimilate data related to the BP oil spill, identify areas where sampling was necessary to guide oil removal, and assess the presence of dispersants.
Petrae noted that as part of the OSAT investigations approximately two dozen vessels were tasked with taking samples and looking for oil that could be removed, along with dispersants. In deep water, investigators looked for depressed oxygen, an indication of the presence of naturally-occurring microbes that consume oil.
Results showed “no oil beyond the shorelines,” Petrae reported.
Among other key findings were no exceedances of the U.S. Environmental Protection Agency (EPA) benchmarks for human health or dispersant levels. However, since August 2010, one percent of water samples taken and approximately one percent of sediment samples exceeded EPA polycyclic aromatic hydrocarbon (PAH) benchmarks for aquatic life. PAHs are toxic substances that are among oil’s hundreds of compounds—but also come from other sources.
Petrae explained that, in all areas outside of three kilometers from the wellhead, where the PAH benchmark was exceeded, “it was from another source” other than oil.
He theorized that the “top kill” attempted to stop the flow of oil had resulted in damage to the well that caused oil to be discharged and settle in the area within three kilometers surrounding the wellhead.
A second OSAT (OSAT-2) was created to investigate health concerns and environmental impacts associated with potential effects of oil residue and provide a benefit analysis of removing that residue versus leaving it in place.
Petrae explained that the National Park Service was interrested in the latter issue with regard to submerged weathered oil on their “nonamenity” beaches, meaning ones where there is little human interaction. He said the park service had requested an analysis of impacts of “intrusive cleaning” that would be required to clean weathered oil off some of these beaches as measured against those of letting the buried oil remain.
Among the key findings of OSAT-2 were that weathered oil samples showed an 86 to 98-percent depletion in its toxicity in the form of PAHs. The study also indicated minimal risk of buried oil on these beaches leaching into groundwater, due to the factors of oil location and its continuing weathering and biodegradation. OSAT-2 further reported that study models predicted that toxicity of most of the oil in question would decrease to 20 percent of current levels within five years.
Regarding human health, OSAT-2 calculated “potential cancer and non-cancer health effects from short and long-term exposure” to the weathered oil at a level below acceptable U.S. Environmental Agency risk and hazard levels.
Petrae said these calculations were based on the assumption of exposure to the oil for 120 days with 40 percent of the body covered with the oil and it being left on the body for 24 hours.
Regarding “aquatic and wildlife resources” OSAT-2 concluded that further cleanup of oil would likely pose a “greater threat” to these resources than from the weathered oil if it were to remain on the beaches.
However, the study noted the potential for “elevated risks” for turtle eggs and hatchlings and “subsurface-probing sea birds” associated with leaving the weathered oil in place on the beaches. Monitoring and further study were recommended to evaluate these risks and develop mitigation strategies….
Read the full story in the April 7, 2011 edition of the Herald Breeze.