What are the tradeoff considerations being weighed regarding the impact of fish and wildlife when making decisions about the subsea use of dispersants?
Dispersants are generally less toxic than oil. When considering the use of a dispersant in the deep ocean, the federal government weighs the effectiveness of the dispersant in breaking down the oil at such depths, the benefits of preventing the oil from rising to the surface and eventually hitting the shore where it is likely to do significant damage to birds, wetlands and aquatic life, and the long term impacts of the dispersant mixed with oil in deeper waters. We have a monitoring and sampling plan in place to track the movement of the oil and we reserve the right to stop the use of these dispersants at any time based on the results.
Are any human health effects expected as a result of using the dispersants?
People working with dispersants are strongly advised to use a half face filter mask or an air-supplied breathing apparatus to protect their noses, throats, and lungs, and they should wear nitrile or PVC gloves, coveralls, boots, and chemical splash goggles to keep dispersants off skin and out of their eyes. CDC provides more information on reducing occupational exposures while working with dispersants during the Gulf Oil Spill Response.
What effects could the use of dispersants have on marine life?
- Material Safety Data Sheet (MSDS) for Corexit 9500A (PDF) (11pp., 88 K, )
- Material Safety Data Sheet (MSDS) for Corexit 9527A (PDF) (11 pp., 132 K, )
It’s important to understand that the use of dispersants is an environmental trade-off. We know dispersants are generally less toxic than the oils they breakdown. We know that surface use of dispersants decreases the environmental risks to shorelines and organisms at the surface and when used this way, dispersants breakdown over several days. However the long term effects on aquatic life are unknown, which is why EPA and the Coast Guard are requiring BP to implement a robust sampling and monitoring plan.
The federal response is intended to ensure that these operations are constantly monitored for any short or long term adverse effects that may outweigh the benefit of using dispersants.
How will we know the future and total effects on marine life of dispersant use?
It is too early in the process to know what the scope of the natural resource damage will be. Look to federal partners such as NOAA and DOI for information on impacts to fish, shellfish, marine mammals, turtles, birds and other sensitive resources as well as their habitats, including wetlands, beaches, mudflats, bottom sediments, corals and the water column.
Apart from marine life, has the Unified Command been able to make an assessment on the effects of the dispersant on the environment?
The harm or toxicity of dispersed oil in the environment is generally associated with the oil rather than with the dispersant alone. However, use of dispersants breaks up a slick of oil on the surface into smaller droplets that can go beneath the surface. When applied on the surface before spills reach the coastline, dispersants will potentially decrease exposure for surface-dwelling organisms (such as sea birds) and intertidal species (such as mangroves and salt marshes), while increasing exposure to a smaller population of aquatic life found deeper in the water. It is unknown if dispersed oil has toxic implications to the human population because bioaccumulation through the food chain has not been evaluated.
To ensure nearby residents are informed and protected, the EPA is constantly monitoring air quality in the Gulf area through air monitoring air craft, and fixed and mobile air stations. EPA is also monitoring the water along the coast for indicators of water quality and toxicity to aquatic life. Following major oil spills, NOAA conducts annual damage assessments to determine and monitor long term effects on shoreline wildlife and spawning habitats.
How will the government ensure the protection of the environment when dispersants are used?
The authorization given to BP to use dispersants on oil stemming from the BP Oil Spill included specific conditions to ensure the protection of the environment and the health of residents in the affected areas. BP, through the Unified Command, continues to monitor the environment for effects of dispersant use. In addition, EPA is collecting air and water quality data daily.
Under the Oil Pollution Act, state, Tribal and federal Natural Resource Trustee agencies are responsible for assessing the injury, loss or destruction of natural resources due to spills. The trustees will also assess any lost human uses of these resources, for example, fishing, hunting, and beach recreational closures. The trustees are also assessing the efficacy of evaluating impacts from the response, including burning, and surface and sub surface dispersant use.