Corexit Nightmare

Like many people who care about the environment, I watched in disbelief as New Zealand authorities started spraying the initial 20 to 50 tonnes of heavy oil that had leaked from the grounded ship MV Rena with Corexit 9500.

My disbelief soon turned to horror when I recalled some of the sinister effects the deadly toxin has caused to the ecology and people living in the Gulf of Mexico.

There is one blessing in disguise with the bad weather; it's temporarily put a halt to the spraying of the deadly dispersant. But it's a very small blessing, being that an unknown amount of Corexit 9500 has already been used and the public has not been adequately warned of its toxicity.

COREXIT 9500 contains between 10-30% of petroleum distillates (solvent). 

Short Term Health Effects - may occur immediately or shortly after exposure:

Contact can irritate the skin and eyes with possible eye damage.
Inhalation of the vapor or fumes can irritate the nose and throat causing coughing and wheezing. Documented symptoms include nausea, vomiting, diarrhea and abdominal pain. Exposure can cause headache, dizziness, confusion, lightheadedness, and passing out.

Chronic Health Effects - The following chronic (long-term) health effects can occur at some time after exposure to 2-Butoxy Ethanol and can last for months or years:

Cancer Hazard - 2-Butoxy Ethanol may be a Carcinogen in humans since it has been shown to cause liver cancer in animals. Many scientists believe there's no safe level of exposure to a carcinogen.

Reproductive Hazard - 2-Butoxy Ethanol may damage the developing fetus.



Authorities should have warned the public and kept them away from areas where they could be exposed to the toxic substance Corexit. They did not and that is unacceptable. They should have organized the health and safety aspect as soon as they decided to use Corexit 9500, not 264 hours afterwards.

Many people have spoken out about the use of the dispersant. Yesterday, the Bay of Plenty Times reported that University of Southampton lecturer in oceanography Dr Simon Boxall told the Science Media Centre the chemicals used to disperse the oil were very toxic and had been banned by countries including Sweden. He said reports dispersants were only as toxic as dishwashing liquid were inaccurate.

Since Rena ran aground on Astrolabe Reef off Tauranga last week, an estimated 300 tonnes of heavy fuel oil has leaked from its ruptured hull. Oil is toxic at 11 parts per million (ppm) while Corexit 9500 is toxic at only 2.61 ppm. Dispersal of the oil does not eliminate it, nor does it decrease the toxicity of the oil… It just breaks it up into small particles, where it becomes less visible, and harder to clean up. Corexit can make the oil sink, where the environmental impact is prolonged.

Many people without protective clothing like PVC gloves were allowed to go down to the beach and touch that toxic oil, which is also contaminated with Corexit 9500. Health warnings were issued well after the spraying of Corexit began. Spraying was also undertaken in breach of the manufacturers guidelines, with Aerial spraying of dispersant within 3.2 km of a boat or 4.8 km of a shoreline.

A report written by Anita George-Ares and James R. Clark for Exxon Biomedical Sciences, Inc. entitled Acute Aquatic Toxicity of Three Corexit Products: An Overview (PDF) states that “Corexit 9500, Corexit 9527, and Corexit 9580 have moderate toxicity to early life stages of fish, crustaceans and mollusks (LC50 or EC50 – 1.6 to 100 ppm.

 Here is the Manufacturer Nalco's MATERIAL SAFETY DATA SHEET (PDF). 

Wikipedia information on Corexit 9500

In response to public pressure, the EPA and Nalco released the list of the six ingredients in Corexit 9500, revealing constituents including sorbitan, butanedioic acid, and petroleum distillates. Corexit EC9500A is made mainly of hydrotreated light petroleum distillates, propylene glycol and a proprietary organic sulfonate. Environmentalists also pressured Nalco to reveal to the public what concentrations of each chemical are in the product; Nalco considers that information to be a trade secret, but has shared it with the EPA.

Propylene glycol is a chemical commonly used as a solvent or moisturizer in pharmaceuticals and cosmetics, and is of relatively low toxicity. An organic sulfonate (or organic sulfonic acid salt) is a synthetic chemical detergent, that acts as a surfactant to emulsify oil and allow its dispersion into water. According to a New York Times article: Ingredients of Controversial Dispersants Used on Gulf Spill Are Secrets No More, the identity of the sulfonate used in both forms of Corexit was disclosed to the EPA in June 2010, as dioctyl sodium sulfosuccinate.