Thank you Judith - well phrased, and thanks to the others for the toxicological perspective.
Two other factors that could be contributing to the increased toxicity of the oil with the dispersants have not been discussed: 1. The lighter oils in the dispersants can act to facilitate biological uptake and increase bioavailability of the heavier oils and of other organic co-contaminants that are present in the Gulf, albeit not necessarily being released by the gusher. This mechanism would act to increase body burdens of the heavier oils and the co-contaminants. 2. The oils in the top layer of the water (which tends to be lighter oils and smaller oil droplets) are exposed to sunlight. Sunlight can cause a photolytic change in the oils which usually causes the oils to be more toxic (ie it's a photoactivation process). And to add to other comments about metabolism - EROD activation is not inherently considered a toxic effect - it's more of an indication of exposure to chemicals (like PAHs) that induce those enzymes. However, even this effect can be down-regulated over time. Some evidence in the literature says that the down-regulation may be due to damage to the enzymes from the bioactivated metabolic product. A second point about EROD induction comes from the cigarette literature - a link has been made between EROD induction and cancer, and that for the chemical(s) tested, the EROD induction was in the direct pathway between exposure to the known carcinogen and the observation of the carcinogenic effect. (Sorry for not looking up the articles here, I do not have easy access to a search engine nor to my office computer from where I am.) Diane Henshel On Wed, Aug 11, 2010 at 9:14 PM, Esat Atikkan <[email protected]> wrote: > It remains incontravertible that there is a new ecological 'baseline' in > the regions of the Gulf that have been affected by the oil eruption. The > breadth of the area affected is still to be assessed, the extent and > duration also still to be assessed. Then again all ecosystems go through > shifting baselines. Now it remains to be seen what the new baseline is and > how it compares to the preceding one. > > E. Esat Atikkan, Ph.D. > Adj. Prof., Biology > Montgomery College, Rockville > Rockville, MD, 20850 > USA > > --- On Wed, 8/11/10, David M. Lawrence <[email protected]> wrote: > > > From: David M. Lawrence <[email protected]> > Subject: Re: [ECOLOG-L] Good news from the Gulf? not so fast... > To: [email protected] > Date: Wednesday, August 11, 2010, 3:22 PM > > > "Metabolize" is not the same as saying their bodies break down the > chemicals with no negative effects. All is says is their bodies process > the chemicals -- but the act of processing the chemicals or their > breakdown products may very well have harmful effects either right away > or at some point in the future. > > I would ask Peterson to explain precisely what he means here. > > Dave > > On 8/11/2010 1:02 PM, Wendee Holtcamp wrote: > > When I went on my Great Gulf Coast Road Trip recently, I visited with > several biologists at the Gulf Coast Research Lab in Ocean Springs MS and > one of them, Mark Peterson, told me that most fish actually metabolize oil > (PAH). This abstract says " These experiments confirm that the use of oil > dispersants will increase the > > exposure of ovoviviparous fish to hydrocarbons in oil." Now I'm not a > physiologist and so now that I've seen the abstract below, and started to > think about it, I'm not quite sure whether that means that they break it > down into less toxic substances and it does NOT really impact them > negatively, or that their gut is now exposed to this PAH/oil and that could > potentially be harmful? Maybe I need to read the paper... > > > > Does anyone know? I'll be writing about this soon so I'd love to talk to > someone who knows a bit more about it (and yes I can follow up with Mark as > well). > > > > I also met with Harriet Perry the lady who discovered that virtually ALL > the blue crab larvae (zoea) she was collecting daily had a little droplet of > oil under their carapace. They get it in there when they molt. So this > raises the possibility of it getting into the food chain. So that makes me > curious - if fish can metabolize PAH/oil in a way that does not harm them > directly (as Mark suggested to me), what about invertebrates like shrimp, > squid, crabs etc? Is there any evidence that they can metabolize PAH, and/or > that there are any sublethal impacts people should be looking for? > > > > Best > > Wendee > > > > > > Blogs for Nature from the Bering Sea ~ http://tinyurl.com/2ctghbl > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Wendee Holtcamp, M.S. Wildlife Ecology ~ @bohemianone > > Freelance Writer * Photographer * Bohemian > > http://www.wendeeholtcamp.com > > http://bohemianadventures.blogspot.com > > ~~ 6-wk Online Writing Course Starts Sep 4 (signup by Aug 28) ~~ > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > I’m Animal Planet’s news blogger - > http://blogs.discovery.com/animal_news > > > > > > -----Original Message----- > > From: Ecological Society of America: grants, jobs, news [mailto: > [email protected]] On Behalf Of Geoffrey Patton > > Sent: Wednesday, August 11, 2010 11:12 AM > > To: [email protected] > > Subject: [ECOLOG-L] Good news from the Gulf? > > > > > > In response to Bill's discussion points, I would like to suggest the > following paper: > > > > Jee Hyun Jung, Un Hyuk Yim, Gi Myeong Han, Won Joon Shim > > Comparative Biochemistry and Physiology, Part C 150 (2009) 218–223 > > Biochemical changes in rockfish, Sebastes schlegeli, exposed to dispersed > crude oil > > Abstract: > > This paper describes the response of the ovoviviparous rockfish, Sebastes > schlegeli, to hydrocarbons in the water-accommodated fraction (WAF) of crude > oil, in the presence or absence of oil dispersants. Concentrations > > of cytochrome P-450 1A (CYP1A) and levels of its catalytic activity > ethoxyresorufin O-de-ethylase (EROD) in rockfish exposed to WAF at > concentrations of 0.1% and 1% were significantly increased by the addition > of a dispersant, Corexit 9500 after 48 h exposure. After 72 h exposure, the > levels of CYP1A and EROD activity were significantly increased in 0.1% and > 0.01% chemically enhanced WAF (CEWAF) (Corexit 9500 and Hiclean II > > dispersant). Bile samples from fish exposed toWAF alone had low > concentrations of hydrocarbon metabolites, exemplified by 1-hydroxypyrene. > After 72 h exposure, hydrocarbon metabolites in bile from fish exposed to > > WAF in the presence of either Corexit 9500 or Hiclean II were > significantly higher compared with fish exposed to WAF alone or control > fish. These experiments confirm that the use of oil dispersants will > increase the > > exposure of ovoviviparous fish to hydrocarbons in oil. > > > > > > > > Cordially yours, > > > > Geoff Patton, Ph.D. > > 2208 Parker Ave., Wheaton, MD 20902 301.221.9536 > > > > --- On Wed, 8/11/10, William Silvert<[email protected]> wrote: > > > > > > From: William Silvert<[email protected]> > > Subject: Re: [ECOLOG-L] Good news from the Gulf? > > To: [email protected] > > Date: Wednesday, August 11, 2010, 4:58 AM > > > > > > I confess that I posted this in large part because I was curious to see > the reactions. As expected, all replies (on- and off-list) were critical and > skeptical. However, although some responses were based on scientific > arguments about issues like long-term burial in sediments, many seemed to be > based on a deep suspicion of any good news about environmental issues and > some relied on conspiracy theories and guilt by association. Curiously no > one mentioned that although lighter fractions of oil dissipate more rapidly > than heavier tars, they tend to be much more toxic. > > > > While I agree that the article paints an incomplete and misleading > picture, I am concerned about a broader issue, namely the willingness of the > scientific community to investigate the possibility that things may not > always be as bad as they seem. For example, some time ago a team of my > colleagues investigated the benthic impacts of bentonite (drilling mud) > around off-shore rigs. To their great surprise they found that the effects > were minor and very localised. I am sure that if they had found something > serious they could have published in Science mag, perhaps even with a press > conference, but as it was I don't even recall whether the work made it past > an internal report. > > > > Work on the benthic impacts of fishing has produced some very surprising > and counter-intuitive results. One colleague in the UK set out to study the > impacts of shellfish dredging, in which massive quantities of sand are > sucked up, pushed through a sieve, and dumped back on the ocean floor. Not > only could he not see anything worth reporting, but after 24 hours he > couldn't even see any evidence of the dredging - the smaller infauna were > all present and seemed fine! > > > > On the other hand, marks from the otter board of a trawler on the > sediments of the Bay of Fundy persist for months in this extremely energetic > environment. I was skeptical of this until I participated in some field work > in an area where the tides are fast and the tidal range is up to 16 m and it > is impossible to moor any kind of enclosure. We did monthly sampling, and > when we returned to the site we could see the marks made by our boots the > month before. It works both ways. > > > > So while I agree in scientific terms with all the criticisms of the > article I posted, I am not comfortable with all the attitudes expressed. I > think we need to be more open-minded and not prejudge the impacts of events. > > > > Bill Silvert > > > > > > ----- Original Message ----- From: "William Silvert"<[email protected] > > > > To:<[email protected]> > > Sent: sábado, 7 de Agosto de 2010 11:44 > > Subject: [ECOLOG-L] Good news from the Gulf? > > > > > > The following article from TIME magazine offers an unusually optimistic > view of the BP spill which I suspect many will disagree with, but which is > worth considering. Bill Silvert > > > > Thursday, Jul. 29, 2010 > > The BP Spill: Has the Damage Been Exaggerated? > > By Michael Grunwald / Port Fourchon, La. > > President Obama has called the BP oil spill "the worst environmental > disaster America has ever faced," and so has just about everyone else. Green > groups are sounding alarms about the "catastrophe along the Gulf Coast," > while CBS, Fox and MSNBC are all slapping "Disaster in the Gulf" chyrons on > their spill-related news. Even BP fall guy Tony Hayward, after some early > happy talk, admitted that the spill was an "environmental catastrophe." The > obnoxious anti-environmentalist Rush Limbaugh has been a rare voice arguing > that the spill - he calls it "the leak" - is anything less than an > ecological calamity, scoffing at the avalanche of end-is-nigh eco-hype... > > > > > > > > > > -- > ------------------------------------------------------ > David M. Lawrence | Home: (804) 559-9786 > 7471 Brook Way Court | Fax: (804) 559-9787 > Mechanicsville, VA 23111 | Email: [email protected] > USA | http: http://fuzzo.com > ------------------------------------------------------ > > "All drains lead to the ocean." -- Gill, Finding Nemo > > "We have met the enemy and he is us." -- Pogo > > "No trespassing > 4/17 of a haiku" -- Richard Brautigan > > > > > -- Diane Henshel Indiana University 1315 E 10th #340 Bloomington, IN 47405 812 855-4556 P 812 855-7802 F [email protected]
