Toxicologia, Ecotoxicologia e Petróleo

A Ecotoxicologia é uma forma de associação entre os saberes da Toxicologia e da Ecologia com vistas a entender e evitar o que poderíamos chamar de intoxicações ambientais. Como ciência, a Ecotoxicologia serve-se, de um lado, do conhecimento da dinâmica ecológica de biomas e de ecossistemas e, de outra parte, do conhecimento da ecotoxicidade de substâncias e produtos químicos. Por ecotoxicidade entenda-se a toxicidade de tais agentes para organismos vivos constituintes das teias de vida dos ecossistemas.

Não avaliar com perícia e dentro das melhores práticas possíveis a ecotoxicidade de produtos químicos que serão intencionalmente adicionados a ambientes é erro grave no que se refere ao gerenciamento do risco toxicológico.
fA análise de risco para tais casos possui metodologia definida e é, em si, também uma ciência. O açodamento ou a irreverência em não se fazer o certo, isto é, a avaliação protocolarmente correta da ecotoxicidade, pode levar a novos desastres ambientais. No caso de produtos químicos que estão sendo empregados para mitigar um desastre por derrame já ocorrido, o resultado pode ser o inverso do que o esperado pela boa intenção.
Assim, interessante debate estabeleceu-se em torno do uso de dispersantes no famigerado desastre por vazamento de petróleo no Golfo do México. Vejamos matérias recentemente divulgadas a esse respeito na imprensa norte-americana.

Scientists: BP dispersants have made spill more toxic

Group working for law firms suing BP cites ‘compelling evidence’

By Amna Nawaz, Rich Gardella and Lisa Myers, NBC News
NBC News Investigative Unit
updated 7/30/2010 7:46:36 PM ET

Editor"s note: Lisa Myers" report on oil dispersants will air Friday on NBC Nightly News.
Amid growing concern about the use of dispersants in the Gulf of Mexico, a group of scientists working for law firms suing BP says their testing indicates that the dispersants being used to break up the oil are making this spill even more toxic to marine life.

Dr. William Sawyer, a toxicologist, is part of a team of scientists hired by law firms — led by Smith Stag of New Orleans — that are representing Louisiana fishermen and environmentalists.

The scientists collected and analyzed globs of oil, sand, and water from more than a dozen sites in four states along the Gulf.

Sawyer told NBC News that the findings are troubling. "We now have compelling evidence that the dispersant has enhanced and increased the toxicity from the spill," he said.

Last week, a group of independent scientists called for an "immediate halt" to the use of dispersants. In what was called a "consensus statement," they warned that dispersants pose "grave risks to marine life and human health."

Spreading the damage?

So far, the federal government has approved use of more than 1.8 million gallons of dispersant in the Gulf. Most of it is Corexit 9500.

One reason relatively little oil is now on the surface of the Gulf"s waters is the use of such a vast quantity of dispersants. The dispersant spreads the oil over a much larger area, which some scientists worry makes it hard for marine life to avoid it.

Studies also have shown that when the dispersant breaks up the oil, it can free the most toxic components — certain hydrocarbons — and spread them throughout the water, exposing marine animals to more toxic components than if the oil hadn"t been dispersed.

Sawyer said their tests show that is now happening in parts of the Gulf. "What we found is a pattern of highly toxic hydrocarbon components that are not normally soluble in seawater, and at levels that are toxic to the marine environment," he said.

Sawyer said these toxic hydrocarbons can be especially harmful to early stages of marine life.

NBC News shared Sawyer"s findings with Dr. Moby Solangi, a biologist at the Institute for Marine Mammal Studies, who has studied how oil spills impact marine life.

Solangi called the findings "very concerning." "The way he [Sawyer] has theorized that the toxicity of the combination of both [oil and dispersant] is of some concern — that needs to be looked at very carefully," Solangi said.

Other scientists told NBC that Sawyer"s theory appears valid, but can"t be proven conclusively without testing the mixture of oil and dispersant on marine life.

Story: Oil dispersants an environmental ‘crapshoot’

A toxic brew

Most recent scientific research has found that combining dispersants with oil makes the oil even more toxic. A review of more than 400 studies since 1997 showed that 75 percent of them found that the combination of oil and dispersant actually increased the toxic effects of the oil.

"I think we all agree that the dispersed oil is more likely to be toxic than the crude oil by itself," says Dr. Joe Griffitt, a toxicologist at the University of Southern Mississippi.

However, so far, the scientific community has not reached any conclusion on whether oil mixed with dispersant is increasing the danger to marine creatures in the case of this particular spill. Part of the problem is that so little is known about use of dispersants in such great amounts or at this depth — 5,000 feet.

BP points out that the federal government has approved its use of dispersants, and that they"ve been "very effective in keeping oil from reaching shore." BP says it"s working closely with the government to monitor the environmental impact, and has committed to spend $500 million over 10 years to study the impact on the Gulf environment.

Nalco, which makes Corexit, says the EPA has concluded that use of Nalco"s dispersants "has not significantly affected the marine environment" and that federal officials have said they resulted in "no harm to aquatic life."

The EPA says "no federal agency has said these products cause no harm to aquatic life","but that its testing so far shows no "significant impact."

Because of potential litigation, the EPA hasn"t seen all of Sawyer"s data. But the agency says it"s now conducting its own tests to determine just how toxic dispersants mixed with oil are to life in the Gulf.

To read statements to NBC News about the use of dispersants from BP, EPA and Nalco, as well as link to a statement from independent scientists opposed to the use of dispersants, click here .

© 2010 MSNBC Interactive.

Statements from BP, EPA, Nalco and scientists on dispersants

TODAY
updated 7/30/2010 12:58:12 PM ET

Below are statements to NBC News from BP, EPA and Nalco regarding BP’s use of dispersants on oil spilled in the Gulf of Mexico, as well as a link to a recent statement on the subject from a group of independent scientists:

BP statement to NBC News:

With regard to the use of dispersants,

- We are working closely with EPA and the Coast Guard to monitor the effect of dispersants on the environment. Dispersants have never been used underwater in this way and we have been working with the agencies to gather as much data as possible to understand the current situation and for the future.

- They have been very effective in keeping oil from reaching the shore.

- Scientists say that given the light quality of the oil, the uses of dispersant, and the natural bioremediation effect of 5,000 feet of water, the oil is extremely weathered when it gets to shore, and the toxic components have greatly if not completely been reduced.

- BP has committed to spend $500 million over 10 years to study the impact of the oil spill on the Gulf environment and will be here for the long run.

EPA statement to NBC News:

There have been no "conclusions" reached about any of this — EPA"s monitoring and research into dispersant is ongoing specifically because we want more information about this chemical"s impact on the environment. No federal agency has said these products cause no harm to aquatic life — what our ongoing sampling tells us, is that — to date — they have not had a significant impact on aquatic life. And the issue is not the dispersant"s ingredients or constituents — which Nalco only released after considerable prodding from EPA — but the way those ingredients are mixed together to form dispersants.

Throughout this crisis, EPA scientists have consulted with all groups, including representatives from academia, non-governmental organizations, industry and other federal and state agencies to ensure we have access to the best available science. These independent scientists have been open and very willing to share their research and data, and it is very unfortunate that this scientist is unwilling to share his full report with EPA.

Still, we hope to have an opportunity to review his full study and discuss the results. EPA continues to conduct its own independent testing into dispersants, and the Agency released data from the first round of testing on June 30 to ensure outside scientists and the public have access to the same data EPA has. The next phase of EPA"s testing is focused on the acute toxicity of multiple concentrations of Louisiana Sweet Crude Oil alone and combinations of Louisiana Sweet Crude Oil with each of the eight dispersants for two test species.

Nalco statment to NBC News:

1. As the EPA said last week, it"s important to remember that oil is enemy number one in this crisis.
2. The EPA has concluded that the use of Nalco"s dispersants — to break apart the oil — has been effective and has not significantly affected the marine environment.
3. Federal officials have repeatedly stated, based on continual air and water sampling and other tests:
a. No harm to aquatic life
b. No indication of any impact in the atmosphere
c. No evidence of worker illness due to dispersant use
4. All of the ingredients contained in the Nalco dispersants are found in common household products, such as food, packaging, cosmetics, and household cleaners. It has been compared to dishwashing detergent by Federal officials.
5. Soon after oil began leaking on April 20, the government requested dispersants from the approved NCP list to help minimize the effects of the accident. Not a drop of Corexit dispersant has been used without the express approval of the federal government.

Consensus statment from independent scientists:

To read a consensus statement from independent scientists opposed to the use of dispersants, click here.

© 2010 MSNBC Interactive.

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