While the daily updates of oil trajectories, continued leaking of oil and fisheries closures may be quite unsettling to many coastal fishermen, they are necessary. Fisheries closures and associated fairways (safety/buffer zones) are an effort to protect consumers, sportsmen and subsistence fishermen from contaminated seafood. Even though petroleum is organic in origin, it is composed of a myriad of hydrocarbon compounds. Polycyclic Aromatic Hydrocarbon (PAH) compounds are the most dangerous, because of their detrimental health effects such as cancer and neurological impacts.
As soon as oil is released in the environment, it begins to break down. That change is described as weathering. As the oil weathers, its chemical properties change. Early weathering includes evaporation of volatile compounds and emulsification, which is the suspension of oil in water. Oil further breaks down through biodegradation by naturally occurring bacteria, photo-oxidation by sunlight and sedimentation. When compared to the Exxon Valdez spill in the cold waters off Alaska, the oil from the Deepwater Horizon spill is weathering faster due to the warm temperatures.
Many state and federal agencies are coordinating an intense sampling and analysis program to ensure that all seafood coming from the Louisiana coastal area is safe to eat. Enforcement of closure areas is also being stepped up. All it would take is one illness outbreak, or for some “tainted” seafood from the Gulf to reach the market place to ruin consumer confidence and cause a reduction in market demand for Gulf seafood. This would have long term economic impacts on the entire region.
The potential for contamination among sea creatures varies. For example, wild finfish are unlikely to become contaminated or tainted because they are either not exposed or exposed only briefly. Wild finfish are mobile and can avoid the oil. Additionally, they rapidly eliminate petroleum compounds taken up. Regulators consider these factors when deciding if seafood is at risk of being contaminated.
Seafood also is evaluated for oil contamination using two methods. Sensory analysis is used to detect off odor or off flavor, which is referred to as tainted seafood. Specially trained inspectors use their sense of smell and taste to detect tainted seafood from a variety of sources including oil spill. Experiences screeners can detect levels of PAH as low as 10 ppm. Further testing of sensory detected seafood is conducted by chemical analysis using sophisticated equipment called gas chromatography and mass spectrometry. This equipment can detect oil compounds at very low levels and can even match it to a source.
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