Off The Menu: Using Restaurants To Fill In Missing Fisheries Data

To manage modern fisheries, scientists have to quantify and monitor populations of animals that live hidden in the vast depths of our oceans. Simply getting the data needed to get a glimpse of what is there now can be difficult, but it’s downright maddening when they try and look backwards to understand how populations of species have changed over time. Some areas have detailed catch records—others, don’t. Sometimes you get a few good decades of government data followed by long gaps in information. But that doesn’t mean the data aren’t out there; sometimes, information is hiding where you least expect it. Scientists have collected fisheries data from photographs, newspapers, and local cultural leaders. Now, a trio of ecologists have tapped another unexpected resource to fill in a 45 year gap in fisheries data in Hawaii: restaurant menus.

Continue reading “Off The Menu: Using Restaurants To Fill In Missing Fisheries Data”

The Very Thick Line Between Raising Concerns And Denialism

The real question is, which side of the line are studies that lack scientific rigor on?
Image credit: silent47

Recently, Kara Moses asked Guardian readers: “Should we wait for conclusive scientific studies before becoming concerned about an issue?” Her personal answer was no; that special interest groups should perform and publicize their own findings. “I believe they should be given a voice,” she concluded, “not dismissed out of hand for lacking the scientific rigour demanded by professional scientists.”

Quick to support her was Treehugger writer Chris Tackett. “The point here is that scientific proof matters in science, but it shouldn’t necessarily be what determines our actions,” he wrote. “We can intuit that some things are unwise or dangerous or against our values without needing reams of scientific data to back up our concerns.” While Kara’s piece talked only about the use of glyphosate (the pesticide known by its brand name RoundUp), Chris used it to attack both the pesticide’s use and Monsanto GM crops.

I understand where they are coming from, but the hair on the back of my neck bristled reading those words. I think they’re both getting into very dangerous territory (or, in the case of Chris’ comments later, happily dancing around in it). The trouble is, it’s one thing to notice a potential danger and raise a few alarm bells to get scientists to investigate an issue — it’s a whole other to publicize and propagandize an unsubstantiated fear despite evidence against it. The former is important, as Kara suggests, and should occur. I have no problem with non-scientists raising honest concerns, if their goal is to have the concerns considered — so long as they’re actually willing to hear what the evidence has to say. The latter, on the other hand, is denialism. You see, once scientists have weighed in, you have to be willing to listen to them. Continue reading “The Very Thick Line Between Raising Concerns And Denialism”

Esteemed Journal Nature Dedicates Issue To GMOs, Defends Technology

Anyone who reads this blog regularly knows I have a big bone to pick with the organic movement, particularly with their constant attack on genetic engineering. I applauded when Prop 37 failed in California, and have put out post after post explaining why GMOs aren’t the root of all evil. That’s not to say I’m pro Monsanto, or think every GMO is science’s gift to humanity. But the universal fear and demonization of all genetic technology is, simply put, damaging and unfounded.

Turn that frown upside-down — the newest Nature issue defends GMOs. Cover image provided by Nature.

Now, the top-tier scientific journal Nature has weighed in. In their “GM Crops: Promise & Reality” issue this week, several articles explore “the messy middle ground.” With titles like “Tarnished Promise” and “A Hard Look At GM Crops,” you might think they attack genetic engineering, but in fact, the entire issue does the opposite, standing in support of crop genetic engineering technologies and pleading to rethink the knee-jerk reaction against them. Even the “Hard Look” concludes, “Tidy stories, in favour of or against GM crops, will always miss the bigger picture, which is nuanced, equivocal and undeniably messy. Transgenic crops will not solve all the agricultural challenges facing the developing or developed world… But vilification is not appropriate either. The truth is somewhere in the middle.”

Which is exactly what I’ve been saying all along.  Continue reading “Esteemed Journal Nature Dedicates Issue To GMOs, Defends Technology”

‘Mystery meat’ takes on a whole new meaning

100% beef… if horses count as beef.

In case you didn’t hear, the big news in the food industry this week is the fact that — *gasp* — horsemeat has been detected in Burger King burgers and Ikea’s Swedish meatballs. Noses worldwide are turning up in disgust at the use of such crude ingredients in ground beef products.*

There’s no doubt that a good part of the fuss is that, for some of the Western world, horsemeat is taboo. Many people have an immediate, visceral reaction to the notion of eating horse, just like Americans generally react strongly to the idea of eating dogs. While our preferences are culturally rooted, the recent labeling exposures don’t just offend our palates. As consumers, we rely on retailers and restaurants to give us accurate information about which foods we are buying — whether it be to avoid allergies, follow religious preferences, choose more sustainable options, or count calories. Now, DNA barcoding is exposing just how often we are duped. Continue reading “‘Mystery meat’ takes on a whole new meaning”

Prop 37 Loses, Scientists Cheer

It comes as no surprise to anyone who reads my blog regularly, follows my Twitter or Facebook feeds, or has talked with me in person lately that I’m pleased to see that Proposition 37 has failed to pass in California. I firmly believe that passing this legislation—as it was proposed—would have been a mistake.

The rallying cry for supporters of this proposition has been “The Right To Know.” It sounds so simple: why shouldn’t people know if their food is genetically modified? What does Monsanto have to hide? But couching the issue in terms of knowledge assumes one thing: that labeling will be in any way informative. In the case of Prop 37, it simply wouldn’t have been. Michael Eisen put it perfectly:

This language reflects the belief of its backers that GMOs are intrinsically bad and deserve to be labeled – and avoided – en masse, no matter what modification they contain or towards what end they were produced. This is not a quest for knowledge – it is a an attempt to reify ignorance.

The simple fact is that there is no evidence that GMOs, as a blanket group, are dangerous. There’s a simple reason for this: not all GMOs are the same. Every plant created with genetic technology contains a different modification. More to the point, if the goal is to know more about what’s in your food, a generic GMO label won’t tell you. Adding Bt toxin to corn is different than adding Vitamin A to rice or vaccines to potatoes or heart-protective peptides to tomatoes. If Prop 37 was really about informed decisions, it would have sought accurate labeling of different types of GMOs so consumers can choose to avoid those that they disapprove of or are worried about. Instead, anti-GMO activists put forward a sloppily written mandate in a attempt to discredit all genetic engineering as a single entity. The legislation was considered so poorly worded that most Californian newspapers rallied against it, with the LA Times calling Prop 37 “problematic on a number of levels”.

By all means, boycott Monsanto, or any food containing their products. Despite rumors to the contrary, I do not support Monsanto in any way (nor do they, in any way, support me). Like many big companies, I think they have had shady business practices at times and are more concerned with their own bottom line than the good of the people or the environment. I’ve already come out strong against RoundUp Ready crops. But my lack of love for Monsanto doesn’t tarnish the fact that GMOs have the potential to dramatically benefit people across the world by providing balanced nutrition and enhancing production in struggling areas. GMOs aren’t inherently evil, and they have the potential to address many of the very real concerns about our current and future food supply.

There’s also another reason that GMOs aren’t considered dangerous: decades of scientific research support their safety. As Pamela Ronald, a UC-Davis plant geneticist, phrased it last year in Scientific American: “There is broad scientific consensus that genetically engineered crops currently on the market are safe to eat. After 14 years of cultivation and a cumulative total of 2 billion acres planted, no adverse health or environmental effects have resulted from commercialization of genetically engineered crops.” Or, as Ingo Potrykus, career plant scientist, put it in a review article for the Journal of Plant Biochemistry and Biotechnology, “GE-technology has an unprecedented safety record and it is far more precise and predictable than any other “traditional” and unregulated breeding technology.”

And, despite the call to arms against GMOs on environmental grounds, a 20 year study published in Nature found that some GM crops can actually improve biodiversity. Because Bt crops reduce pesticide spraying, scientists saw increases in populations of ladybugs, lacewings and spiders. Even more impressive, these benefits weren’t just seen in Bt fields—these upsides spread to the fields near them. And it’s just one of many studies refuting the ecological argument against GMOs.

Based on the growing body of scientific literature, numerous scientists and scientific organizations have come out in defense of genetic engineering technologies and against labeling initiatives like Proposition 37, including the American Association for the Advancement of Science (AAAS), the American Medical Association, the National Academy of Sciences and the World Health Organization. The AAAS statement put it succinctly: “Legally mandating such a label can only serve to mislead and falsely alarm consumers.”

The proponents of Prop 37 sought to use rhetoric and language to sway against science. They used the word “right” to smother dissent—after all, how can anyone debate against someone’s “rights”? They tried to capitalize on people’s lack of knowledge of the science of genetic engineering to push their own political agenda. Instead of stimulating discussion and understanding of genetically modified foods, they sought to guilt or scare people into making rash decisions. So yes, I’m happy to see that they have failed. Californians have stood in defense of science, and should be applauded for it.

Are lower pesticide residues a good reason to buy organic? Probably not.

A lot of organic supporters are up in arms about the recent Stanford study that found no nutritional benefit to organic foods. Stanford missed the point, they say—it’s not about what organic foods have in them, it’s what they don’t. After all, avoidance of pesticide residues is the #1 reason why people buy organic foods.

Yes, conventional foods have more synthetic pesticide residues than organic ones, on average. And yes, pesticides are dangerous chemicals. But does the science support paying significantly more for organic foods just to avoid synthetic pesticides? No.

A Pesticide Is A Pesticide

 

I’m not saying that pesticides, herbicides, and insect repellants aren’t toxic. I certainly wouldn’t recommend drinking cocktails laced with insect-repelling chemicals, for without a doubt, they can be bad for you. Pesticide exposure has been linked to all kinds of diseases and conditions, from neurodegenerative diseases like Parkinson’s to cancer. What we do know, though, is that natural isn’t synonymous with harmless. As a 2003 review of food safety concluded, “what should be made clear to consumers is that ‘organic’ does not equal ‘safe’.”

I’ve said it before and I’ll say it again: there is nothing safe about the chemicals used in organic agriculture. Period. This shouldn’t be that shocking – after all, a pesticide is a pesticide. “Virtually all chemicals can be shown to be dangerous at high doses,” explain scientists, “and this includes the thousands of natural chemicals that are consumed every day in food but most particularly in fruit and vegetables.”

There’s a reason we have an abundance of natural pesticides: plants and animals produce tens of thousands of chemicals to try and deter insects and herbivores from eating them. Most of these haven’t been tested for their toxic potential, as the Reduced Risk Program of the US Environmental Protection Agency (EPA) applies to synthetic pesticides only. As more research is done into their toxicity, however, we find they are just as bad as synthetic pesticides, sometimes worse. Many natural pesticides have been found to be potential – or serious – health risks, including those used commonly in organic farming.

In head-to-head comparisons, natural pesticides don’t fare any better than synthetic ones. When I compared the organic chemicals copper sulfate and pyrethrum to the top synthetics, chlorpyrifos and chlorothalonil, I found that not only were the organic ones more acutely toxic, studies have found that they are more chronically toxic as well, and have higher negative impacts on non-target species. My results match with other scientific comparisons. In their recommendations to Parliament in 1999, the Committee on European Communities noted that copper sulfate, in particular, was far more dangerous than the synthetic alternative. A review of their findings can be seen in the table on the right (from a recent review paper). Similarly, head to head comparisons have found that organic pesticides aren’t better for the environment, either.

Organic pesticides pose the same health risks as non-organic ones. No matter what anyone tells you, organic pesticides don’t just disappear. Rotenone is notorious for its lack of degradation, and copper sticks around for a long, long time. Studies have shown that copper sulfate, pyrethrins, and rotenone all can be detected on plants after harvest—for copper sulfate and rotenone, those levels exceeded safe limits. One study found such significant rotenone residues in olives and olive oil to warrant “serious doubts…about the safety and healthiness of oils extracted from drupes treated with rotenone.” Just like with certain synthetic pesticides, organic pesticide exposure has health implications—a study in Texas found that rotenone exposure correlated to a significantly higher risk of Parkinson’s disease. The increased risk due to Rotenone was five times higher than the risk posed by the synthetic alternative, chlorpyrifos. Similarly, the FDA has known for a while that chronic exposure to copper sulfate can lead to anemia and liver disease.

So why do we keep hearing that organic foods have fewer pesticide residues? Well, because they have lower levels of synthetic pesticide residues. Most of our data on pesticide residues in food comes from surveys like the USDA’s Pesticide Data Program (PDP). But the while the PDP has been looking at the residues of over 300 pesticides in foods for decades, rotenone and copper sulfate aren’t among the usual pesticides tested for—maybe, because for several organic pesticides, fast, reliable methods for detecting them were only developed recently. And, since there isn’t any public data on the use of organic pesticides in organic farming (like there is for conventional farms), we’re left guessing what levels of organic pesticides are on and in organic foods.

So, if you’re going to worry about pesticides, worry about all of them, organic and synthetic. But, really, should you worry at all?

You Are What You Eat? Maybe Not.

 

We know, quite assuredly, that conventionally produced foods do contain higher levels of synthetic chemicals. But do these residues matter?

While study after study can find pesticide residues on foods, they are almost always well below safety standards. Almost all pesticides detected on foods by the USDA and independent scientific studies are at levels below 1% of the Acceptable Daily Intake (ADI) set by government regulators. This level isn’t random – the ADI is based on animal exposure studies in a wide variety of species. First, scientists give animals different amounts of pesticides on a daily basis throughout their lifetimes and monitor those animals for toxic effects. Through this, they determine the highest dose at which no effects can be found. The ADI is then typically set 100 times lower than that level. So a typical human exposure that is 1% of the ADI is equivalent to an exposure 10,000 times lower than levels that are safe in animal models.

Systematic reviews of dietary pesticide exposure all come to the same conclusion: that typical dietary exposure to pesticide residues in foods poses minimal risks to humans. As the book Health Benefits of Organic Food explains, “while there is some evidence that consuming organic produce will lead to lower exposure of pesticides compared to the consumption of conventional produce, there is no evidence of effect at contemporary concentrations.” Or, as a recent review states, “from a practical standpoint, the marginal benefits of reducing human exposure to pesticides in the diet through increased consumption of organic produce appear to be insignificant.”

Reviews of the negative health effects of pesticides find that dangerous exposure levels don’t come from food. Instead, non-dietary routes make for the vast majority of toxin exposures, in particular the use of pesticides around the home and workplace. A review of the worldwide disease burden caused by chemicals found that 70% can be attributed to air pollution, with acute poisonings and occupational exposures coming in second and third. Similarly, studies have found that indoor air concentrations of pesticides, not the amount on foodstuffs, correlate strongly to the amount of residues found in pregnant women (and even still, there was no strong correlation between exposure and health effects). Similarly, other studies have found that exposures to toxic pyrethroids come primarily from the environment. Children on organic diets routeinely had pyrethroids in their systems, and the organic group actually had higher levels of several pyrethroid metabolites than the conventional one. In other words, you have more to fear from your home than from your food.

Your home probably contains more pesticides than you ever imagined. Plastics and paints often contain fungicides to prevent mold—fungi that, by the way, can kill you. Your walls, carpets and floors also contain pesticides. Cleaning products and disenfectants contains pesticides and fungicides so they can do their job. Ever used an exterminator to get rid of mice, termites, fleas or cockroaches? That stuff can linger for months. Step outside your house, and just about everything you touch has come in contact with a pesticide. Insecticides are used in processing, manufacturing, and packaging, not to mention that even grocery stores use pesticides to keep insects and rodents at bay. These chemicals are all around you, every day, fighting off the pests that destroy our buildings and our food. It’s not surprising that most pesticide exposures doesn’t come from your food.

That said, there are some studies that have found a link between diet and exposure to specific pesticides, particularly synthetic organophosphorus pesticides. Lu et al. found that switching children from a conventional food diet to an entirely organic one dropped the urinary levels of specific metabolites for malathion and chlorpyrifos to nondetectable levels in a matter of days. But, it’s important to note that even the levels they detected during the conventional diet are three orders of magnitude lower than the levels needed in animal experiments to cause neurodevelopmental or other adverse health effects.

While it might seem that decreasing exposure to pesticides in any way could only be good for you, toxicologists would differ. Contrary to what you might think, lower exposure isn’t necessarily better. It’s what’s known as hormesis, or a hormetic dose response curve. There is evidence that exposure to most chemicals at doses significantly below danger thresholds, even pesticides, is beneficial when compared to no exposure at all. Why? Perhaps because it kick starts our immune system. Or, perhaps, because pesticides activate beneficial biological pathways. For most chemicals, we simply don’t know. What we do know is that data collected from 5000 dose response measurements (abstracted from over 20,000 studies) found that low doses of many supposedly toxic chemicals, metals, pesticides and fungicides either reduced cancer rates below controls or increased longevity or growth in a variety of animals. So while high acute and chronic exposures are bad, the levels we see in food that are well below danger thresholds may even be good for us. This isn’t as surprising as you might think—just look at most pharmaceuticals. People take low doses of aspirin daily to improve their heart health, but at high chronic doses, it can cause anything from vomiting to seizures and even death. Similarly, a glass of red wine every day might be good for you. But ten glasses a day? Definitely not.

No Need To Fear

 

To date, there is no scientific evidence that eating an organic diet leads to better health.

What of all those studies I just mentioned linking pesticides to disorders? Well, exactly none of them looked at pesticides from dietary intake and health in people. Instead, they involve people with high occupational exposure (like farmers who spray pesticides) or household exposure (from gardening, etc). Judging the safety of dietary pesticide intake by high exposures is like judging the health impacts of red wine based on alcoholics. A systematic review of the literature found only three studies to date have looked at clinical outcomes of eating organic – and none found any difference between an organic and conventional diet. My question is: if organic foods are so much healthier, why aren’t there any studies that show people on an organic diet are healthier than people eating conventionally grown produce instead?

More to the point, if conventional pesticide residues on food (and not other, high exposure routes) are leading to rampant disease, we should be able to find evidence of the connection in longitudinal epidemiological studies—but we don’t. The epidemiological evidence for the danger of pesticide residues simply isn’t there.

If dietary exposure to pesticides was a significant factor in cancer rates, we would expect to see that people who eat more conventionally grown fruits and vegetable have higher rates of cancer. But instead, we see the opposite. People who eat more fruits and vegetables have significantly lower incidences of cancers, and those who eat the most are two times less likely to develop cancer than those who eat the least. While high doses of pesticides over time have been linked to cancer in lab animals and in vitro studies, “epidemiological studies do not support the idea that synthetic pesticide residues are important for human cancer.” Even the exposure to the persistent and villainized pesticide DDT has not been consistently linked to cancer. As a recent review of the literature summarized, “no hard evidence currently exists that toxic hazards such as pesticides have had a major impact on total cancer incidence and mortality, and this is especially true for diet-related exposures.”

The closest we have to studying the effects of diet on health are studies looking at farmers. However, farmers in general have high occupational pesticide exposures, and thus it’s impossible to tease out occupational versus dietary exposure. Even still, in this high-risk group, studies simply don’t find health differences between organic and conventional farmers. A UK study found that conventional farmers were just as healthy as organic ones, though the organic ones were happier. Similarly, while test-tube studies of high levels of pesticides are known to cause reproductive disorders, a comparison of sperm quality from organic and conventional farmers was unable to connect dietary intake of over 40 different pesticides to any kind of reproductive impairment. Instead, the two groups showed no statistical difference in their sperm quality.

In a review of the evidence for choosing organic food, Christine Williams said it simply: “There are virtually no studies of any size that have evaluated the effects of organic v. conventionally-grown foods.” Thus, she explains, “conclusions cannot be drawn regarding potentially beneficial or adverse nutritional consequences, to the consumer, of increased consumption of organic food.”

“There is currently no evidence to support or refute claims that organic food is safer and thus, healthier, than conventional food, or vice versa. Assertions of such kind are inappropriate and not justifed,” explain scientists. Neither organic nor conventional food is dangerous to eat, they say, and the constant attention to safety is unwarranted. Worse, it does more harm than good. The scientists chastise the media and industry alike for scaremongering tactics, saying that “the selective and partial presentation of evidence serves no useful purpose and does not promote public health. Rather, it raises fears about unsafe food.”

Furthermore, the focus on pesticides is misleading, as pesticide residues are the lowest food hazard when it comes to human health (as the figure from the paper on the right shows). They conclude that as far as the scientific evidence is concerned, “it seems that other factors, if any, rather than safety aspects speak in favor of organic food.”

If you don’t want to listen to those people or me, listen to the toxicologists, who study this stuff for a living. When probed about the risk that different toxins pose, over 85% rejected the notion that organic or “natural” products are safer than others. They felt that smoking, sun exposure and mercury were of much higher concern than pesticides. Over 90% agreed that the media does a terrible job of reporting the about toxic substances, mostly by overstating the risks. They slammed down hard on non-governmental organizations, too, for overstating risk.

What’s in a Name?

There’s good reason we can’t detect differences between organic and conventional diets: the labels don’t mean that much. Sure, organic farms have to follow a certain set of USDA guidelines, but farm to farm variability is huge for both conventional and organic practices. As a review of organic practices concluded: “variation within organic and conventional farming systems is likely as large as differences between the two systems.”

The false dichotomy between conventional and organic isn’t just misleading, it’s dangerous. Our constant attention to natural versus synthetic only causes fear and distrust, when in actuality, our food has never been safer. Eating less fruits and vegetables due to fear of pesticides or the high price of organics does far more harm to our health than any of the pesticide residues on our food.

Let me be clear about one thing: I’m all for reducing pesticide use. But we can’t forget that pesticides are used for a reason, too. We have been reaping the rewards of pesticide use for decades. Higher yields due to less crop destruction. Safer food because of reduced fungal and bacterial contamination. Lower prices as a result of increased supply and longer shelf life. Protection from pests that carry deadly diseases. Invasive species control, saving billions of dollars in damages—and the list goes on. Yes, we need to manage the way we use pesticides, scrutinize the chemicals involved and monitor their effects to ensure safety, and Big Ag (conventional and organic) needs to be kept in check. But without a doubt, our lives have been vastly improved by the chemicals we so quickly villainize.

If we want to achieve the balance between sustainability, production outputs, and health benefits, we have to stop focusing on brand names. Instead of emphasizing labels, we need to look at different farming practices and the chemicals involved and judge them independently of whether they fall under organic standards.

In the meantime, buy fresh, locally farmed produce, whether it’s organic or not; if you can talk to the farmers, you’ll know exactly what is and isn’t on your food. Wash it well, and you’ll get rid of most of whatever pesticides are on there, organic or synthetic. And eat lots and lots of fruits and vegetables—if there is anything that will improve your health, it’s that.

Before you say otherwise and get mad at me for mentioning it, rotenone is currently a USDA approved organic pesticide. It was temporarily banned, but reapproved in 2010. Before it was banned, it was the most commonly used organic pesticide, and now—well, without public data on pesticide use on organic farms, we have no idea how much it is being used today.

Food picture from FreeFoto.Com

Fish with Melanoma – Our Enduring Environmental Legacy

We’ve all heard the horror stories. Melanoma is one of the most dangerous kinds of skin cancer, killing around 50,000 people worldwide every year. If caught early enough, it can be cured, but once it invades past the skin, it’s deadly. On the advice of doctors, we try to protect ourselves, donning floppy hats and coat upon coat of SPF 50 sunblock. We pick over our bodies in the mirror regularly, looking for dark, irregularly-shaped spots. The recent rise in the incidence of skin cancer, though, is our own fault. It is the result of our environmental hubris, a combination of a chemically-depleted ozone layer and our pathological obsession with a tanned physical appearance. Now, we’re becoming increasingly aware that our choices don’t just impact our own species. The rest of life has to deal with our poor decisions, and studies are just now determining the wide-ranging consequences of our actions.

Histology of healthy skin (left) and melanoma-

diseased skin (right) from coral trout

Unable to slather on sunscreen, the creatures on our planet are much more limited in their ability to deal with the sun’s radiation. Some, like the red seabream, are able to tan much like we do, increasing the melanin content in their skin to defend against damaging rays. But most animals are not so lucky, and are ill-equipped to deal with drastic changes in UV radiation. Yet drastic changes in UV radiation are exactly what occurred in the late 20th century, when chemicals we used as refrigerants and in aerosol sprays quickly depleted one of the most UV-protecting molecules, ozone, from our atmosphere. From 1972 to 1992, places like Australia saw a 20% increase in UV radiation levels, and colder areas like Antarctica saw ozone decreases of 50 percent or more, creating large ozone holes which allow more than double the normal level of UV radiation to pass through.

In the late 1970s, scientists began to realize that certain chemicals we were producing, called chlorofluorocarbons, or CFCs, were making their way into the stratosphere. These chemicals release chlorine atoms which, when combined with cold temperatures, begin a destructive chain reaction that turns UV-blocking ozone into oxygen. By 1987, there was so little protective ozone in the stratosphere over Antarctica that global lawmakers decided CFCs were too dangerous to go unchecked. They established the Montreal Protocol, which set strict limits on the use of CFCs. In the 25 years since, the ozone layer has rebounded some, but it is still 50 to 70 years away from returning to pre-1980s levels. Now, the ozone layer is under a new threat: climate change. Scientists predict that rising carbon dioxide levels will lead to more ozone holes, as carbon dioxide and other greenhouse gasses trap heat at the surface, chilling the stratosphere, and allowing atmospheric chlorine atoms to wreak havoc.

We are only now beginning to fully document the consequences of ozone depletion. In people, the loss of ozone at the end of the 20th century was directly connected to a 16 to 60 percent increase in the incidence of skin cancer. But while we carefully documented the effects on our own species, little research has looked for health effects on other animals. Now, Australian scientists have found an entire population of fish plagued with the deadliest form of skin cancer: melanoma.

The team of researchers from Newcastle University began looking for skin cancer in the commercially and culturally important species of coral trout off Australia in 2010 when a different team of scientists studying sharks first noticed lesions. Because these other scientists from The Australian Institute of Marine Sciences were catching trout to study predator-prey dynamics, Michael Sweet and his colleagues were able to screen over a hundred coral trout (Plectropomus leopardus) for melanoma between August 2010 and February 2012. They examined lesions histologically, to determine the exact type and severity of the cancer. Lastly, they tested lesions for bacteria and viruses, to rule out a microbial cause.

A healthy coral trout (top) as compared to

trout with melanoma

A whopping 15% of the fish surveyed had melanoma. “Studying disease in wild fish populations is very time-consuming and costly so it’s hard to say how long the disease has been around,” explains lead author Michael Sweet. “What we do know is that it is now widespread in the coral trout population. We found evidence of cancer in the common coral trout, the bar-cheeked coral trout, and the blue spotted coral trout.”

While 15% sounds high, Sweet and his colleagues believe it’s only a minimum estimate. “Once the cancer spreads further you would expect the fish to become quite sick, becoming less active and possibly feeding less, hence less likely to be caught. This suggests the actual percentage affected by the cancer is likely to be higher than observed in this study.”

This isn’t the first melanoma to be found in fish, as individual cases have been identified in a wide variety of species, from catfish to nurse sharks. Never before, however, has melanoma been found population-wide. “To the best of our knowledge, cancer of any sort has never been shown in a wild marine fish population before, making this a first for science,” said Sweet

While it is a first, Sweet and his colleagues don’t think coral trout are unique. “We would not be surprised to find [melanoma] in other species as well,” he said, “including some of the smaller reef species.” So far, skin cancer in fish has likely been overlooked due to the high cost of evaluating fish for disease as well as the low likelihood of sick and weakened fish landing in fishermen’s or scientists’ hands.

Extensive laboratory analyses ruled out microbial agents as the driver of the disease, and since the fish were caught far from shore in a marine protected area, it’s unlikely that pollution factored in, either. The samples were also directly compared to UV-induced melanomas in laboratory fish, which are used as a model for human disease; the ones in coral trout looked identical to the lab-created cancers. “This combination of evidence leads us to suspect UV as the casual agent.”

If UV is the cause, then it’s really our fault. “The occurrence of this disease in today’s day and age and not before can be linked to the changes we are experiencing in our climate and the ozone hole,” explained Sweet. “It is highly likely there will be higher prevalence around areas which have these ‘ozone holes’.” While the Montreal Protocol has helped reverse some of the worst damage, Sweet is careful to note that we’re not out of the woods yet. “An increase in smaller ozone holes (other than the two large ones of the Arctic and the Antarctic) is thought to be occurring, and this has been related by other researchers to be due to climate change.”

The overall effect of skin cancer in fish populations could be devastating. In laboratory fish, melanoma cuts the lifespan of Xiphophorus species from four years to only six months, and makes them more susceptible to small changes in their environment like fluctuations in temperature. “It is unclear whether future changes in the ocean environment or climate will similarly exacerbate the effect of melanomas in wild P. leopardus populations,” write the authors, “but clearly further research is urgently needed to understand the distribution, prevalence, ecological and fisheries significance of this syndrome.”

Since lawmakers are hesitant to restrict greenhouse gasses and other pollutants, we’re stuck with whatever happens, for now – especially, as Sweet notes, when it comes to disease. “Without addressing the underlying issues, sadly, there is likely no feasible or practical cure for skin cancer in wild fish populations.” If melanoma is found in other species, too, the consequences will only magnify.

With little natural protection against UV rays, fish and most other species are at our mercy when it comes to radiation-induced disease. Skin cancer only adds to a growing list of pathological consequences to our poor ecological choices – a list which includes devastating diseases like chytridiomycosis and avian malaria. Until we change the way we treat the world around us, that list will continue to grow, while the abundance and vitality of our planet’s biodiversity shrinks.

 
Citation: “Evidence of melanoma in wild marine fish populations.” M J Sweet, N Kirkham, M Bendall, L Currey, J C Bythell, M Heupel. PLOS ONE. August 2012. DOI: 10.1371/journal.pone.0041989.g005

Histological sections from the paper; photos of coral trout by Michelle Heupel

Conservation is important – for the sake of our health

Growing up, I was one of those lucky kids who wasn’t allergic to anything. I felt like I was invincible – while my friends were pestered by pollen or peanuts, I was able to eat and play with reckless abandon. Childhoods like mine, however, are becoming more and more scarce. A recent study found that in 2008, peanut allergies in kids were three and a half times higher than a decade before, with similar trends occurring in a number of food allergies. Similarly, the prevalence of hay fever in developed countries has increased about 100 percent in each of the last three decades. It’s not just allergies – other chronic inflammatory diseases, from arthritis to asthma, continue to rise in our populations. A new paper in the Proceedings of the National Academy of Sciences suggests that perhaps the problem isn’t what we’re putting into our environment, but what we’re removing from it: that the loss of biodiversity is negatively impacting our health.

One of the most popular hypotheses to explain the rise in inflammatory conditions is known as the Hygiene Hypothesis, which says that our increasingly sterile lifestyle is to blame for our allergic reactions. We now live in a world of antibacterial soaps, instant hand sanitizer, vaccines, and antibiotics, all of which have taken over the job of protecting our children from dirt and germs. Left with nothing to do, kid’s immune systems get a little stir crazy, and start attacking even minor invaders like pollen with increased zeal. But Ilkka Hanski and his colleagues from the University of Helsinki in Finland suggest the Hygiene Hypothesis extends beyond how clean we keep our house. They put forward a Biodiversity Hypothesis, which suggests that less contact with the nature and biodiversity is adversely affecting the microbes on and in our bodies, leading to increased susceptibility to immune disorders.

To test this hypothesis, the research team investigated the relationship between biodiversity, allergen susceptibility, and skin microbial communities in a little over 100 randomly chosen teenagers in Finland. The kids grew up in a variety of settings, from tightly-packed villages to rural farmlands. For each participant, they measured how sensitive their skin was to allergens and what kind of microbes were living on there. Based on their skin’s immune reaction, they classified the students as allergen-sensitive (a condition known as atopy) or not. The researchers also roughly calculated the level of environmental biodiversity where the participants lived by looking at the amount of plant cover of their yards and the major land use types within 3 km of their homes, allowing comparisons between it and the participant’s allergy sensitivity and skin microorganisms.

The team found a strong, significant correlation between the diversity of a particular class of skin bacteria, called gammaproteobacteria, and allergen sensitivity. Though they only represented 3% of the skin bacterial community, gammaproteobacteria were the only class that showed a significant decrease in diversity in the atopic individuals. So, to get a closer look at this phenomenon, directly comparing the presence of different gammaproteobacteria with levels of an anti-inflamatory marker, IL-10, in the subjects’ blood. The presence of one gammaproteobacterial genus, Acinetobacter, was strongly linked to higher levels of IL-10 in healthy individuals but not in the allergen-sensitive ones. As the authors explain, this suggests that these microbes may help teach the immune system to ignore pesky allergens.

“The positive association between the abundance of the gammaproteobacterial genus Acinetobacter and IL-10 expression… in healthy individuals, but not in atopic individuals, is consistent with IL-10’s central role in maintaining immunologic tolerance to harmless substances.” Thus, the authors say, “the lack of association between Acinetobacter and IL-10 expression in atopic individuals in the present study might re?ect a breakdown of the regulatory mechanisms.”

How, exactly, Actinetobacter and other gammaproteobacteria influence our immune system has yet to be determined. What the authors did show is that environment a person grows up in has a strong effect on the presence and diversity of this group of bacteria. Since gammaproteobacteria are are commonly found in soil and on plants (including ?owering plants and their pollen), it may not seem that surprising to the researchers that the environmental diversity around a subject was strongly correlated to increased diversity of their skin gammaproteobacteria. But what is astounding is that this relationship held even when the researchers stepped back and looked at the overall connection between allergen sensitivity and the surrounding environment; the more natural biodiversity where the kid grew up, the less likely he or she was to be sensitive to allergens.

“The present results demonstrate that biodiversity can be surprisingly strongly associated with atopy.”

This suggests that the urban-dwelling nature of developed countries may be to blame for their increasing problem with inflammatory diseases. If so, conservation of natural spaces, including parks and other green initiatives, may be key to protecting the health of future generations. “Interactions with natural environmental features not only may increase general human well being in urban areas, but also may enrich the commensal microbiota and enhance its interaction with the immune system, with far-reaching consequences for public health.”

Since allergies cost us almost $14.5 billion annually including medical expenses, missed school and work, and over the counter drugs, there may be a strong monetary incentive to conserve our natural areas – if only for the sake of our health. That’s not even considering the other economic incentives for conservation, including water filtration and storm protection, which have been estimated at over $4.4 trillion dollars per year.

What all these studies tell us is that the cost of conservation is strongly outweighed by its benefits. Period.

 

Reference: Hanski, I., von Hertzen, L., Fyhrquist, N., Koskinen, K., Torppa, K., Laatikainen, T., Karisola, P., Auvinen, P., Paulin, L., Makela, M.J. & Environmental biodiversity, human microbiota, and allergy are interrelated, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1205624109

Image of soil and hands © Soil-Net.Com under a Creative Commons License

sciseekclaimtoken-4fb07e8178ad6

Mounting Evidence Suggests Sharks Are In Serious Trouble

Can you imagine oceans without sharks? We may soon have to, as new research suggests may already be 90% of the way there.

Studying shark populations can be tricky. As David Shiffman explains well, while there are a number of methods that can be used to study shark populations, quantifying just how far their numbers have fallen can be difficult. However, recent research out of the University of Hawaii suggests that the presence of humans has a severe and strong negative impact on sharks, driving down numbers by over 90%.

Sharks play a vital role in coral reef ecosystems. Yet every year, millions are killed for asian delicacies and disproven cancer cures. There is no question our shark fishing habits have devastated their populations; the only questions that remain are how much of an effect are we having, and can the sharks recover.

In an effort to answer the first, the research team crunched data from 1607 surveys from the NOAA Coastal Reef Ecosystem Division (CRED) to calculate the effect of human habitation on shark populations. The CRED team counted sharks throughout the Pacific using towed diver surveys, the most efficient and effective way to study open ocean creatures on a large spatial scale, and compared their counts with local human population numbers. Their results were clear – and sobering.

“Around each of the heavily populated areas we surveyed — in the main Hawaiian Islands, the Mariana Archipelago and American Samoa — reef shark numbers were greatly depressed,” said Marc Nadon, lead author of the study. “We estimate that less than 10% of the baseline numbers remain in these areas.”

The team also looked at other factors that might be affecting shark populations, including temperature and reef productivity. However, while sharks preferred warmer waters full of potential prey, the negative impact of humans dwarfed these effects. “Our results suggest humans now exert a stronger influence on the abundance of reef sharks than either habitat quality or oceanographic factors,” the authors wrote.

The team estimated that less than 100 people is enough to cut shark populations by 20%. Even 1,000 people – which is much less than the population of many small islands in the Pacific – was enough to decrease shark populations by 60%. As Nadon put it, “In short, people and sharks don’t mix.”

The findings are consistent with other research in the field. A 2003 paper, for example, found that shark populations in the Northwestern Atlantic dropped over 65% between 1986 and 2000. Similarly, a 2010 paper estimated that shark populations in the Chagos Archipelago had declined 90% since the 1970s. The more we study sharks, the worse the picture becomes, and the stronger the case becomes for conservation efforts. We simply cannot continue to treat these animals the way we do now, for all scientific evidence suggests the day is fast approaching when there will be no sharks left to exploit.

Reference: Nolan et al. Re-Creating Missing Population Baselines for Pacific Reef Sharks. Conservation Biology; DOI: 10.1111/j.1523-1739.2012.01835.x

Reflections On The Gulf Oil Spill: Conversations With My Grandpa | Observations

Two years ago, an explosion on the Deepwater Horizon oil platform led to the spilling of almost five million barrels of oil in just a handful of months. I wrote the following post in June of that year, two months after the spill began. Even now, we still don’t really know how much of an effect the oil spilled and the subsequent cleanup efforts will have on the Gulf ecosystem. At least, as I conclude in this post, I hope we have learned our lesson.

Oil supplies the United States with approximately 40% of its energy needs. Billions upon billions of gallons are pumped out of our wells, brought in from other countries, and shipped around to refineries all over the states. 1.3 million gallons of petroleum are spilled into U.S. waters from vessels and pipelines in a typical year. Yes, it would be great if we never spilled a drop of oil. No matter how hard we may try, though, the fact is that nobody is perfect, and oil spills are an inevitable consequence of our widespread use of oil. The question is, once the oil is out there, how do we clean it up?

Nowehere is this issue more glaring than in the Gulf of Mexico right now, where 35,000 to 60,000 barrels of oil are spewing out of the remains of the Deepwater Horizon drilling rig every day. The spill has enraged an entire nation. But perhaps my grandfather put it best, when I asked him what he thought about how BP and the US is responding to the spill.

“They’re friggin’ idiots.”

Ralph Bianchi.jpgMy grandfather, Ralph Bianchi, knows a thing or two about oil spills. He spent thirty years in the oil spill cleanup business. His company, JBF Scientific (now a part of Slickbar), developed new technologies for cleaning up spills, including a skimming method called the Dynamic Inclined Plane (DIP). In 1970, they sold their first skimmer to the U.S. Environmental Protection Agency. The next year, the U.S. Navy purchased forty $250,000 DIP skimmers and stationed them at major naval installations throughout the world. When word of how well his designs worked for the government, private oil companies started buying DIP skimmers, too.

In 1987, my grandfather’s company, JBF Scientific, received a call from the Alyeska Pipeline Service Company. The company, based in Alaska, was formed in 1970 and charged with the duty of designing, constructing, operating and maintaining the pipeline which transports oil from the fields in Alaska. It is owned by the major oil companies that operate the Trans-Alaska Pipeline System, including a couple you may have heard of: BP and Exxon Mobil.

The DIP Skimming System

Part of Alyeska’s job is to clean up any spills which occur in the process of the movement of oil to, from and through the pipeline. What they wanted from my grandfather was a DIP skimmer larger than he’d ever constructed – a boat over 120 feet long. JBF drew up plans for a massive DIP skimmer capable of removing 2,500 barrels of oil per hour. But when my grandfather told them how much it would cost – an estimated $4 to $5 million at the time – Alyeska instead decided to try another company’s cheaper model, which turned out to be close to useless in the kelp-filled waters of the Northwest.

Of course, everyone knows what happened next. In 1989, the Exxon Valdez ran aground on Prince William Sound’s Bligh Reef and spilled an estimated 250,000 barrels of crude oil, creating one of the worst environmental disasters in history. The spill itself was bad enough, but Alyeska, Exxon and the country were entirely unprepared to deal with a cleanup of that nature. Despite months of cleanup efforts, less than 10% of the spilled oil was recovered, and 20 years later, the ecosystems in the area had still yet to recover.

the Valdez Star Oil Skimming Vessel.jpgAfter the spill, Alyeska bought my grandfather’s skimmer. The boat, called the Valdez Star, still operates in that area today. If another spill the size of the Exxon Valdez occurred now, picking up that volume of oil would only be a few days’ work for the Valdez Star and two aluminum oil recovery boats the company also bought. Only a few days work.

If only the cooperative in Alaska had been willing to spend a little more on their cleanup equipment! Other areas, however, were and are much better about their cleanup planning. One of the first privately owned groups to embrace the DIP skimmers was the oil cooperative in Puget Sound. Puget Sound and the Northwest Straits are among the busiest shipping lanes in the world, with billions of gallons of oil moving across the waters of Puget Sound every year. The Sound may have many environmental issues, including stormwater runoff and pollution, but it kicks butt at cleaning up oil spills.

Despite the fact that oil spills occur there fairly frequently, you don’t hear about them much. That’s because in Puget Sound, they have what my grandfather calls a “firehouse mentality.” The cooperative bought the first privately owned DIP skimmer, The North Sounder, from JBF in the late 1980s. After the Exxon spill, they purchased three more similar skimmers, and a 600 ton skimmer like the Valdez Star called The Shearwater. These skimmers are among a fleet of equipment and trained personnel ready at a moment’s notice to deal with any spill. They run drills to practice different methods of cleanup. They know the currents and wind data and predict where and when the oil will hit. They’ve identified sensitive shore areas like shell fish beds, bird feeding and nesting ground and yachting harbors, and have stationed containment and deflecting booms, storage barges, and skimmers at those areas. And all of it is funded by the state and the oil companies and other shippers whose oil could be spilled. In Washington, the state Ecology Department has a budget of $16 million, while companies spend roughly $41 million a year there preparing for spills.

Bianchi Oil Cleanup 1972.jpgOil spill cleanup using my grandpa’s technology in 1972; my uncle Robert Bianchi on the left, a family friend Mark Mendano in the center, and my uncle Raimond Bianchi on the right.

In Puget Sound, when a spill happens, they jump into action. Just like firefighters responding to an alarm, trained teams of workers immediately assess the situation and combat the spreading problem. They contain the oil if they can, and if they can’t, they protect the areas that are most vulnerable to oil’s damaging effects. Similar oil cleanup crews are now in place in a number of harbors around the country.

So I asked my grandfather how many skimmers he sold to companies in the Gulf.

“None.”

comparing skimmer models.pngBP now claims that 400 or so skimmers are now working to clean up the oil spilling in the gulf. One of their spokesmen, Mark Proegler, says skimmers are only able to collect about 10-15 percent of the oil. “They essentially scoop up the oil and water mix in the water for later separation,” he explained, “and that mix is about 10 percent oil and 90 percent water.”

But that’s because they aren’t using DIP skimmers, or other, better skimming technologies that have been developed over the past few decades. The resultant oil percentage of the fluids that are picked up by these skimmers is more than five times higher. When deciding how well prepared an area is for an oil spill, the government tends to operate on a 20% rule of thumb (33 CFR 155, Appendix B, Section 6) – that is, they assume that any skimmer will operate at only 20% the efficiency that the manufacturer claims. For JBF DIP models, however, they assume 74% to 94% efficiency.

What my grandfather wants to know is why the Valdez Star and the Shearwater, as well as the other large, high-quality skimmers, aren’t in the Gulf right now. Better boats are out there, which could clean up more oil and faster.

It’s not just that BP and other Gulf companies hadn’t embraced the newer, better cleanup technologies before this disaster occurred. It’s that they aren’t prepared at all for any kind of large spill. That’s what the US government discovered when they performed exercises in the early 2000s to see how companies would respond to a major spill. The After Action report of the 2004 Spill of National Significance (SONS) exercise concluded that, in the Gulf of Mexico:

Oil spill response personnel did not appear to have even a basic knowledge of the equipment required to support salvage or spill cleanup operations…. There was a shortage of personnel with experience to fill key positions. Many middle-level spill management staff had never worked a large spill and some had never been involved in an exercise.

What’s even more sobering is that of the oil spills within the Coast Guard’s jurisdiction (i.e., marine and coastal areas), approximately 50% of the incidents, both in number and the volume of oil spilled, occur in the Gulf of Mexico and its shoreline states.

Why doesn’t the Gulf have the “firehouse mentality” of areas like Puget Sound? Why haven’t they identified the most vulnerable areas and stationed cleanup equipment there, provided up to date training for cleanup personnel, and generally prepared for this kind of disaster?

The answer is simple. As my grandpa phrased it, “they’re cheap bastards.”

The lack of foresight and constant corner cutting by BP led to this disaster. But what’s worse is that they continue to botch the containment and cleanup of the billions of gallons of oil that their mistakes have spilled.

“The real issue,” my grandfather explained to me, “is that they don’t care about solving the problem.” By they, he wasn’t just referring to BP. He was referring to all of the oil companies in the Gulf and the government regulators that are supposed to be ensuring that oil drilling and transport occurs safely. “They throw dispersants on the oil. Do you know what dispersants do? They make the oil neutrally buoyant. Dispersed oil winds up in the water column and, therefore, cannot be deflected by floating booms or harvested with oil skimmers. They make the surface look cleaner, but they don’t do a damned thing to actually clean up the oil.”

Essentially, dispersants are soaps. They emulsify oil, breaking up up and allowing it to mix into water. The idea behind dispersants is that by breaking up the oil and putting it in the water column, it will be degraded faster by the microorganisms that naturally degrade oils and keeping the oil from coating the shoreline.

Starting in May, the US has been spraying oil dispersants at the spill like mad, despite concerns raised by many related to potential dispersant impact on wildlife and fisheries, environment, aquatic life, and public health. The EPA further approved injection of these dispersants directly at the the leak site to break up the oil before it reaches the surface. By the end of may, over 600,000 gallons of dispersants have been applied on the surface, with another 55,000 gallons applied underwater. The two main dispersants being used, Corexit EC9500A and EC9527A are neither the least toxic, nor the most effective, among the dispersants approved by the Environmental Protection Agency. In fact, the UK has banned their use entirely. When BP was asked why they aren’t using better dispersants, they said that Corexit was ‘what they had available.’

The bigger question, though, is why are they using dispersants at all. Multiple studies after the Exxon Valdez spill found that dispersants, detergents, and hot water cleaning of shoreline cause substantially more mortality than oil itself. Even before the Exxon spill, scientists knew that “dispersant-oil mixtures are more toxic than the dispersant alone, and many-fold more toxic than the crude oil.” While better and safer detergents are being developed, their long-term toxicity and effectiveness is still completely unknown, making them risky to use in such high quantities as BP is.

The way my grandpa sees it, the so-called cleanup of the Deepwater Horizon Oil Spill isn’t about being effective or safe, it’s about looking like they’re doing something. The goal is to make it less visible so the public forgets that it’s happening. It’s all about PR.

I think he’s right.

What needs to happen, in the Gulf of Mexico and throughout the United States, is a change of mindset. We’ve already started moving away from oil to other, more responsible and sustainable energy technologies, but that is only a small part of the solution. The truth is, we’re likely never going to have a zero demand for oil. We certainly won’t do it in the next fifty or a hundred years – it’s just not feasible. While we need to continue to research alternatives, we need to deal with how we handle and regulate oil now, too.

Oil companies have been taking advantage of loose regulations for too long. They need to be forced to prepare for the damage their products can cause. You would think that after the disaster in Alaska that we would have learned our lesson – that anywhere where oil is drilled, pumped or transported would have put in place well trained emergency response teams and extensive equipment ready to react to large spills. But apparently, we haven’t learned from our mistakes. This time, I hope that we do.

This post was chosen as an Editor's Selection for ResearchBlogging.orgThis post has been chosen as a Research Blogging Editor’s Selection, featured in the 33rd edition of Scientia Pro Publica, and now won the Post with the Most!

PS: For amazing coverage of the oil spill in general, check out my blog-buddies over at Deep Sea News and the growing list of fantastic posts/feeds/etc from Southern Fried Science

Citations:

  • Jonathan L. Ramseur (2010). Oil Spills in U.S. Coastal Waters: Background, Governance, and Issues for Congress Congressional Research Service , 7-5700 (RL33705)
  • USCG Spill Compendium (2005). Cumulative Data And Graphics For Oil Spills (1973-2004)
  • Ralph A. Bianchi, Edward E. Johanson, & James H. Farrell (1973). The Application of Skimmers, Piston Films,and Sorbents for Open Water Spills Offshore Technology Conference
  • U.S. Department of Homeland Security, & U.S. Coast Guard (2004). California SONS 2004 After Action Report
  • Paine, R., Ruesink, J., Sun, A., Soulanille, E., Wonham, M., Harley, C., Brumbaugh, D., & Secord, D. (1996). TROUBLE ON OILED WATERS: Lessons from the Exxon Valdez Oil Spill Annual Review of Ecology and Systematics, 27 (1), 197-235 DOI: 10.1146/annurev.ecolsys.27.1.197
  • SWEDMARK, M., GRANMO, A., & KOLLBERG, S. (1973). Effects of oil dispersants and oil emulsions on marine animals Water Research, 7 (11), 1649-1672 DOI: 10.1016/0043-1354(73)90134-6
  • CM Tarzwell (1971). Toxicity of oil and oil dispersant mixtures to aquatic life. Water pollution by oil. London, The Institute of Petroleum. P. Hepple (Ed.) , 263-272