Oil Is More Toxic Than We Thought, Study Finds

Bad news for the Gulf of Mexico: a study released this week sheds new light on the toxicity of oil in aquatic environments, and shows that environmental impact studies currently in use may be inadequate….

The key finding involved the embryos of Pacific herring that spawn in the [San Francisco Bay, which was hit by an oil spill in 2007]. The fish embryos absorbed the oil and then, when exposed to UV rays in sunlight, physically disintegrated. This is called phototoxicity, and has not previously been taken into account when talking about oil spills.

Photos from a UC Davis/NOAA study show the effects of phototoxicity in Pacific herring embryos. Embryos on the left are unexposed to oil; those on the right have been in oil and then exposed to sunlight and show cells destroyed.

After the BP oil disaster, I wrote about the toxicity of oil (see “BP’s dispersants are toxic — but not as toxic as dispersed oil“).  Turns out oil is even more toxic than we thought, as a new study from the UC Davis Bodega Marine Laboratory in collaboration with NOAA finds.

The Proceedings of the National Academy of Sciences study is titled, “Unexpectedly high mortality in Pacific herring embryos exposed to the 2007 Cosco Busan oil spill in San Francisco Bay” (subs. req’d).  That spill occurred when a “tanker hit the San Francisco-Oakland Bay Bridge and spilled 54,000 gallons of bunker fuel into the bay.”

Here’s more from the L. A. Times on the phototoxicity study:

“This phenomenon had been observed in the laboratory, but had never been observed in the field, and there were even some skeptics out there wondering if this was just a phenomenon that people would see under lab conditions,” said Gary Cherr, director of the marine lab and professor of environmental toxicology.

“One of the real take-home messages from our study was: yes, in fact, it definitely happens in the real world.”

This is another big jump in understanding the real damages from oil spills. Studies of the 1989 Exxon Valdez spill created an entirely new understanding of oil damage when it was found that oil was toxic in minute quantities measured in parts-per-billion and even parts-per-trillion – much lower than previously recognized. This finding of phototoxicity, however, presents a new challenge.

Phototoxicity is a phenomenon that is well known to human users of certain antibiotics, which can cause a rash if the person is exposed to direct sunlight. It has also long been associated with crude oil and creosote, which can cause a nasty redness on human skin when combined with sun exposure.

“It’s kind of a new paradigm in thinking about the toxicity of oil,” adds Cherr. “Up until now, there has been this awareness of it in the laboratory studies, but it has not been taken into account in the real world, in environmental analyses, and certainly in regulating the amounts of oil that are spilled.”

In the wake of BP’s 2010 Deepwater Horizon blowout in the Gulf of Mexico, for example, much of the spilled oil stayed at depth, but that which did rise through the water column could have produced phototoxic effects that are still unknown and unstudied.

The bottom line:  We need to prevent the oil spills in the first place with strong oversight.

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7 Responses to Oil Is More Toxic Than We Thought, Study Finds

  1. Raul M. says:

    mineral oil is photo toxic. Mineral oil is a common ingredient of sun tan oils.
    Personally, I like the good health effects of flax seed oil. It’s omega fatty acid is good for all body cell types.

  2. catman306 says:

    “Never put anything on your skin that you wouldn’t eat.” -health proverb (that works)

  3. Raul M. says:

    Still haven’t found reference for the third ingredient that combines with glucosimine and chondrotine which when combined clears the walls of arteries and veins.
    Did see that the third combiner is found in some vegetables my guess is onions.
    But, many of the health ingredients are derived from ocean life.
    As in glucosimine and chondrotine one from cartilage and the other from particular type of crustations.
    Sorry fir the spelling errors.

  4. Joan Savage says:

    Sigh. How can we be surprised, when basic undergraduate lessons in life sciences explain so much of this?
    One of the most basic lessons in organic chemistry is about C=C bonds, and how they respond to different wavelengths of light.
    One of the most basic lessons in biology is the necessity of a lipid bilayer to form a cell membrane.
    Crude oil is a mix of alkanes, cycloalkanes and various aromatic hydrocarbons. The aromatic hydrocarbons all have C=C bonds and some of the alkanes also. The petroleum can adhere to the lipid and the integrity of the cell membrane is altered or destroyed.
    Add light radiation that affects the C=C bonds, and why wouldn’t it get even more difficult for the living cell?

  5. Bluestocking says:

    Interesting, isn’t it, that so many of the things which humans do turn out to be more harmful than we had thought far more often than they turn out to be more beneficial than we had thought?

    Frankly, if anything, the fact that people were skeptical of phototoxicity despite the existence of real-life analogs (such as the redness which appears on human skin when it comes in contact with crude oil and then exposed to sunlight) suggests that that oil was not really “more toxic than we thought” as much as “more toxic than we wanted to and were prepared to accept.” To quote one of my favorite authors, “Man is not a rational animal — he is a rationalizing one.”

  6. Susan Anderson says:

    Pretty much as expected. But will the public learn about it? I doubt it.

    Please do take a look at The Big Fix trailer (#4 Prokaryotes link, thanks).

    [Raul, I take glucosamine/chondroitin every day for my (thankfully former) joint troubles, and suffer when I forget (years). No ill effects yet. Label says shellfish ingredients, but you’ll find it at any vitamin display in drugstores; it’s made me mobile again.] AFAIK it’s not harmful to humans.