Wednesday, March 15, 2017

Dear Mr. Pruitt, let's talk about lead

Dear Mr. Pruitt,
Last week I wrote to you about DDT. This week let’s consider lead. Like DDT, another jaw-dropper for my environmental toxicology undergrads. You may not remember leaded gasoline. It was phasing out just as you were probably hitting the road. But I do, and I remember feeling good about asking for “unleaded” at the pump. Those were the days when the tetra-ethyl lead added to gas was called just “ethyl.” The manufactures, a combination of Dupont, Standard Oil and General Motors, branded their new company and their product with a young woman’s name, leaving out the second half – the lead — that literally drove men crazy if not to their death. The chemical helped gas burn more efficiently; a good thing. And it helped the oil industry dominate the automobile industry by pushing aside other possible fuels or fuel additives, like ethanol.
Lead is another opportunity to discuss the  struggle between those who tried to protect Americans and the nation’s workers and an industry that values profit over all. A struggle that is now something you must face almost daily. In this case Alice Hamilton, a tireless and pioneering advocate for worker health who, along with others, tried to get the lead out as early as 1925. This was just a year after workers at the so-called House of Butterflies died; one of them in a straitjacket, his brain poisoned by the additive. There is also the story of how tetra-ethyl, a product of American Industry, helped launch the Nazi Related imageLuftwaffe (leaded fuel was a necessity for their airplanes). And the story of how the industry, when asked by the surgeon general if public health impacts of the new additive had been considered, apparently assured him, sans any data, that the streets would be “…so free from lead that it will be impossible to detect..”*
Industry assurances and oil politics aside, I don’t need to exaggerate, advocate or hammer home the benefits of chemical regulation when it comes to lead.
Despite Hamilton and colleagues’ best efforts, the industry went on to use, at its peak in 1970, some 250,000 tons of lead in gasoline. That is hundreds of thousands of tons of lead pried from the earth’s crust and spewed into our air, water and soil. The sheer magnitude of lead used in gasoline was another shocker for students alerted to the problem of lead more recently via the recent news from Flint, Michigan and elsewhere. A generation who now equates lead with old pipes and drinking water. Those were the days when there was an average of 2-3 gramsof lead in every gallon of gasoline. My mother’s Country Squire, the old wood paneled station wagon, much like today’s Escalades, Land Cruisers and Suburbans (which have only slightly improved mileage) burned through about a gallon of gasoline every twelve miles. Living in the suburbs our family contributed plenty of lead to our neighborhood, the back streets of Boston and points north and south. (Back of the envelope: 10,000 miles of travel per year, 833 gallons of gas meant roughly 2000 grams, or 70 ounces of lead, a year.) Over the courses of my childhood, my mother’s car added a little less than my own body weight at the time, ninety pounds of lead,  to our environment. And that was just one car — my dad’s black VW bug (roughly 20 MPG) contributed it own fair share. I don’t think these  are numbers anyone could be proud of. No matter who you are, where you live or what political party you belong to.
Label for Ethyl Gasoline AdditiveBy the 1960’s the national average for lead in blood rose to somewhere around 600 parts per billion (we can’t blame this all on ethyl, our homes – inside and out – were coated in the stuff as well.) It’s likely that my sisters and I carried in our blood, lead levels that would now be considered high  – although most likely,  we were better off than kids living in the city. Today, we worry about children with blood lead over 50 parts per billion. We also know that aside from the more immediate poisonous effects, even in small amounts lead can lower children’s I.Qs and alter their behavior.
That my students were clueless about leaded gasoline, is, in large part thanks to the EPA. When your agency ordered manufacturers to phase-out lead and find a replacement, it was not only an EPA victory, but a victory for all Americans. Here is Carol Browner as the final nails hit the lead coffin in 1996:
The elimination of lead from gas is one of the great environmental achievements of all time. Thousands of tons of lead have been removed from the air, and blood levels of lead in our children are down 70 percent. This means that millions of children will be spared the painful consequences of lead poisoning, such as permanent nerve damage, anemia or mental retardation.
Why even talk about leaded gasoline? Because like DDT, this was another triumph of your agency. Another victory over powerful industries that put profits over human health. Lead is clearly still a problem – particularly for municipalities and homes with aging pipes and in too many cases lead paint – legacies from our earlier generations, that sadly keep on giving. But we all still use gasoline. And, both the automobile industry and the oil industry have retained if not grown in power over the decades. I would love to provide my students with current examples of good Corporate Citizens. I’d like to say, “That was then, this is now.” There is plenty of opportunity for the corporations that impact the quality of the air we breath and must hold  responsibility for our health and for our changing climate (I understand you disagree here – so I won’t belabor this point). With nearly a century of exposure to oil combustion products – the health-science is indisputable.  As you advocate for a smaller EPA, and consider the current CAFE (fuel economy) standards, I would very much appreciate some examples to share with my public health students, so that they can rest assured that they won’t be telling their students jaw-dropping stories from the time that EPA handed its authority over to big oil and the auto industry.
Featured Image: Sign on an antique gasoline pump, advertising gasoline additive (tetraethyl lead) by the Ethyl Corporation. Photo taken at the highway rest stop on I-94 westbound, east of Bismarck, North Dakota, USA. Plazak, 2010.
*Midgley, T. Jr., 1922, Letter to Cumming, National Archives Record Group 90, 30 December 1922

Friday, March 10, 2017

Dear Mr. Pruitt, today we talked about DDT

Dear Mr. Pruitt,
I teach an introductory environmental toxicology class to undergraduate public health majors. Each week we talk about different issues from mercury to DDT and nanomaterials. And each week, inevitably, we talk about the EPA. I am a child of the 1960s, the age when it finally dawned on us that for all the benefits of modern industrial chemicals – from plastics to mosquito-free evenings — maybe there was a dark side to welcoming these new products into our homes and releasing billions of tons of new chemicals into our environment. We talk about what happened, or didn’t, before the EPA reined in pesticides, air pollutants, water pollutants. This week’s topic was DDT and the beginning of pesticide regulation.
DDT
Life Magazine ad, meant to show safety of DDT
First I need to tell you, I am not someone who eats all organic all the time. I realize that until we have better solutions, some growers will use pesticides to save their crops. And not everyone can grow (or buy,) organic. I know that not all pesticides are problematic, and more often it is over-reliance or over-use that is the problem. But I can also say this with some level of comfort because these pesticides are registered and regulated by our federal agencies, most importantly the EPA. Though, I have add that there is plenty of room for improvement! I’ve seen only a couple of applications for pesticide registration and I think even you would be surprised by the amount of missing information.
As the new administrator, I am sure you know the history of DDT, Silent Springand the emergence of the EPA. But did you know that some of the first pesticide regulations (pre-EPA) focused on “immediate” harm rather than long-term? Then the EPA began to require consideration of other “adverse” effects and environmental effects. Eventually DDT and similar pesticides were banned. Even so, we still live with their legacy. A recent study has linked DDE exposure at a young age (or even possibly in utero) with an increased incidence of breast cancer in women.
While it would be nice to be able to say “of course, we know so much more now, that can’t happen again.” That there won’t be another DDT. My students know that some day in their life-time there will be another DDT. Maybe it won’t be a pesticide. Maybe it won’t accumulate in the environment. But, some new miracle chemical or maybe even gene product will have effects that could — without pressure by agencies like yours – cause the next generation to look back with disbelief, asking how could this happen?
Making new pesticides, safer pesticides is costly with all the hoops and testing that must be done. And we’ve learned so much from past mistakes. I haven’t read much about what your intentions are towards pesticide regulation and enforcement – but the cuts proposed in EPA’s budget and some of your past efforts seem like you might lean towards deregulation. If that is the case do you really honestly believe, that this current generation and their kids, will be better off without federal regulation of pesticides? I would love to believe that industry would regulate itself – but they haven’t a good track record for self-regulation.We can learn from past mistakes, but then we have to apply what we learn. If you have some examples that show otherwise, I would love to share them with my class.
By their very nature, there will always be things we don’t know about new products. The qualities that make them useful is often their novel activity (nanochemicals are a great example of that.) Look, in the beginning, no one knew DDT would hang around for decades. Or that humans would end up with more DDT in their bodies than was permitted in the food they ate. Or that it might cause breast cancer decades later. But had producers been pushed to ask some of these questions – we might be free of these chemicals today, rather than having molecules produced over half a century ago still jiggling around in  our love handles and muffin tops.
Your family as well as mine and this current generation of college kids are all better off today than in the days before the EPA. This is thanks in large part, to your predecessors and all those who now work for you. Let’s move forward together, rather than backwards.
Best, Emily

Monday, January 23, 2017

About Twelve Percent

Ok, I’ve had it. Too many times on the news, I’ve heard something like this, “after all, 53% of white women voted for Donald Trump.” Or, "42% of women voted for Trump."  WRONG. What they mean of course is the percentage of those who actually voted. But too often that part is dropped. Like here in the New York Times "About 53 percent of white women voted for Mr. Trump, according to exit polls." As my husband says, that's asking a reader to do some work to realize that doesn't mean 53% of all white women who are eligible to vote. 
Consider that only 59% of total eligible voters in our country voted. And assume that also means roughly 59% of women  (more women than men voted so could be a little more) for which we match up woman to man almost 1:1 if not a bit more, depending on the state. And OF THOSE 42% voted Trump. Which means, about 12% or so (like I said, a little more if there are more women than men) of all women who can vote in our country voted Trump.
Or approximately: 0.59*0.5*0.42=0.123. (This also means that, roughly, only 16% of women in our country who could vote, voted for Clinton.)
One friend suggests that maybe the media is trying to hold us voters accountable when they throw around figures (for so few voting in general). Which may be the case. But with all the fake news today, it's more important than ever to be accurate with our numbers. Let's not take the percentages out of context.

Tuesday, January 10, 2017

Trump's war on science, a shot over the bow

I was hoping that maybe Trumps anti-vax statements would be one of those things he backtracked on (I have in my head the little tune from Scrubs, Wrong, wrong, wrong, wrong,); but his recent ask, this one to Robert Kennedy Jr, a well-know anti-vaxxer who  maintains that the MMR vaccine causes autism (despite the overwhelming science), to chair "a commission on vaccination safety and efficacy," suggests otherwise. I don't know why I'm surprised. Says Kennedy, "We ought to be reading the science and debating the science." 
I've been writing about vaccines for a few years in different contexts. Below is an excerpt from my upcoming book. The book is about how we can reduce our dependence on drugs and chemicals like pesticides, by relying on natural allies. One of those allies is our own immune response, this excerpt from a chapter about tech advances in vaccine development includes a bit about Maurice Hilleman, the virologist who developed the vaccine anti-vaxxers love to hate (along with many other vaccines):
The concept of a vaccination is simple enough: vaccines provoke immunity by exposing individuals either to pathogens that have been weakened or killed so that they can no longer cause full-on disease, or to bits of pathogens. But pathogens are wildly diverse, and a vaccine strategy that works for one disease may not work for others. Some are fairly straightforward—for example, injecting weakened or killed polio virus provides lasting protection. (Since 2000, the United States has used only killed polio virus.) When I was vaccinated as a kid, I likely received the next best thing to a natural infection: live but weakened versions of polio, mumps, and measles. A generation later, most of my children’s shots were filled with inactivated or killed viruses, or bits of microbes.[i] Kids today do still receive some attenuated (weakened) virus vaccines, notably against mumps, measles, and rubella.
Many of these twentieth-century vaccines began with Maurice Hilleman, a virologist and vaccine developer who spent most of his career at Merck Pharmaceutical. The mumps vaccine my kids received may even be traced back to the 1963 mumps virus that once infected Hilleman’s own daughter, Jeryl Lynn. As he tells the story, one night she woke complaining of a sore throat. “Oh my god,” said Hilleman, pointing to the glands under his chin and holding out his hands, “her throat was like this.” Though rare, a mumps infection can have serious complications, from permanent hearing loss to life-threatening brain swelling. There was no vaccine. So Hilleman raced to the lab and grabbed some swabs. Three years later, he treated his one-year-old daughter Kirsten with a vaccine he had developed from Jeryl Lynn’s virus. “Here was a baby being protected by a virus from her sister, and this has been unique in the history of medicine. . . . It was a big human-interest story.”[ii] Hilleman, who passed away in 2005, is credited not only with developing dozens of vaccines but also saving more lives than any scientist before him. But, as the authors of an article in Science about twenty-first-century vaccine development pointed out in 2013, “By the latter part of the twentieth century, most of the vaccines that could be developed by direct mimicry of natural infection with live or killed/inactivated vaccines had been developed.”[iii] In other words, the most manageable pathogens, like mumps, were under control. What’s left for vaccine makers are the problem pathogens.... They are also confronted with a growing trend of distrust in vaccines. Ironically, vaccination critics are part of a population that has benefited greatly from vaccines, largely avoiding the raft of infectious diseases that plagued earlier generations.
Yet no matter how many lives vaccines save, there is no skirting the issue. Vaccination is a medical intervention. We inject newborns and toddlers—the most vulnerable members of society, who cannot decide for themselves. Some parents worry about their kids receiving too many vaccines at once. Others are concerned by the small amounts of toxic chemicals like formaldehyde and ethyl mercury used to kill or to preserve vaccines. Some believe conspiracy theories about vaccines spreading disease. And many have been frightened by a now-discredited study accusing the MMR vaccine (also developed by Hilleman) of causing autism. Some of these concerns contain an unsettling kernel of truth. A portion of the polio vaccines that my generation—millions of children—received were contaminated with the monkey virus, SV40. Until the 1960s, polio vaccine was grown and isolated from green monkey cells. Hilleman and a colleague discovered the virus; a couple of years later, another researcher showed that the virus caused cancerous tumors in hamsters. By the time vaccine makers had replaced monkey-cell cultures with human cell cultures, an estimated 100 million of us baby boomers had been vaccinated. Fifty years later, despite much suspicion and study, the virus has not yet been shown to cause cancer in humans.[iv]...
While there may always be unintended consequences of vaccines, the role they have played (and continue to play) in saving lives over the past century has been huge. Now vaccine makers have the tools to develop increasingly safer vaccines, effective against some of the most obstinate pathogens—and they can do so more rapidly.
Adapted from  Natural Defense: enlisting bugs and germs to protect food and health (Island Press, Spring 2017)

[i]. Centers for Disease Control and Prevention, “U.S. Vaccines,” Appendix B-2, April 2015, http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/B/us-vaccines.pdf, accessed August 9, 2016.
[ii]. For a video story by Maurice Hilleman, see: The College of Physicians of Philadelphia, “Mumps: Jeryl Lynn Story,” The History of Vaccines, October 29, 2004, http://www.historyofvaccines.org/content/mumps-jeryl-lynn-story, accessed August 9, 2016.
[iii]. Wayne C Koff et al., “Accelerating Next Generation Vaccine Development for Global Disease Prevention,” Science 340 (2013) doi:10.1126/science.1232910, accessed August 9, 2016, 2.
[iv]. Vicent Rancaniello, Virology (blog), http://www.virology.ws/2010/04/13/poliovirus-vaccine-sv40-and-human-cancer/, accessed October 2016.
[v]. Polio Global Eradication Initiative, “Vaccine-Derived Polio Viruses,” http://www.polioeradication.org/polioandprevention/thevirus/vaccinederivedpolioviruses.aspx, accessed August 9, 2016.

Monday, December 19, 2016

Toxic Textiles: Book review of Fake Silk

Book Review. Below is an excerpt from my recent review of:Fake Silk The Lethal History of Viscose Rayon Paul David Blanc, Yale University Press. The review first appeared in Science, 25 Nov 2016:Vol. 354, Issue 6315, pp. 977
In this slim, action-packed book, Paul David Blanc takes the reader on a historical tour that touches on chemistry, occupational health, and the maneuverings of multinational corporations. Our guide is a small, “elegant” molecule called carbon disulfide—a compound that is a key ingredient in the making of viscose (better known as rayon) and is also insidiously toxic, having devastated the minds and bodies of factory workers for more than a centuryFake Silk: The Lethal History of Viscose Rayon unveils a story that, in Blanc’s words, “deserves to be every bit as familiar as the cautionary tale of asbestos insulation, leaded paint, or the mercury-tainted seafood in Minimata Bay.” Who knew that the fabric that has had its turn on the highfashion runway, as a pop-culture joke (remember leisure suits?), and more recently as a “green” textile had such a dark side?
Rayon is a cellulose-based textile in which fibers from tree trunks and plant stalks are spun together into a soft and absorbent fabric. First patented in England in 1892, viscose-rayon production was firmly established by the American Viscose Company in the United States in 1911. Ten years later, the factory was buzzing with thousands of workers. “Every man, woman, and child who had to be clothed” were once considered potential consumers by ambitious manufacturers.
However, once the silken fibers are formed, carbon disulfide—a highly volatile chemical— is released, filling factory workrooms with fumes that can drive workers insane. Combining accounts from factory records, occupational physician’s reports, journal articles, and interviews with retired workers, Blanc reveals the misery behind the making of this material: depression, weeks in the insane asylum, and in some cases, suicide. Those who were not stricken with neurological symptoms might still succumb to blindness, impotency, and malfunctions of the vascular system and other organs. For each reported case, I could not help but wonder how many others retreated quietly into their disabilities or graves.
Yet, “[a]s their nerves and vessels weakened, the industry they worked for became stronger,” writes Blanc.  In Fake Silk, he exposes an industry that played hardball: implementing duopolies and price-fixing and influencing federal health standards. For more see here. (Though you may need a subscription or library to access the rest.)

Thursday, December 15, 2016

An antibiotic alternative? Hope through science.

Antibiotic resistance test. Image: Dr. Graham Beards
A toddler suddenly becomes deathly ill. In the ER she is diagnosed with dysentery, caused by a rare but particularly aggressive form of Salmonella. One antibiotic after another fails because the strain, picked up when her family was traveling across parts of Asia, resists multiple antibiotics; but there is an alternative new drug. Like a guided missile, the drug targets only the disease causing Salmonella. Not only that, but as long as Salmonella remains, the drug particles replicate, increasing in number until the infection subsides. Despite the carnage, the toddler’s gut microbiome remains unharmed – no need for probiotics or fear of complications like C. diff.  If Salmonella responds by evolving resistance, the drug may respond in turn engaging an ages old evolutionary dance. By the next morning the color returns to her cheeks. By evening, she is cured.
While still a fantasy here is the U.S., the scenario has been playing out in Eastern European hospitals and clinics for nearly a century. The “new” drug is a virus called a bacteriophage (or simply “phage”), that attacks bacteria. It is a cure nearly as old as life; at least as old as bacteria. Microbiologists have suggested that for every strain of bacteria on earth from the oceans to those populating our own microbiomes– there is at least one, if not multiple bacteriophages.
phage
Viral phages infecting a bacterium. Image: Dr. Graham Beards
As diseases like TB, gonorrhea, E.coli, staph and other common infections increasingly evolve to resist our antibiotics, health care workers are fast becoming desperate for new antimicrobials that are both effective and cause minimal damage to our own microbiomes. Bacteriophages are potent antimicrobials. Once disparaged here in the U.S. and in western medicine in general, these bacteria infecting viruses are making their way back into academic and biotech laboratories. If all goes well, they may be coming to a pharmacy near you.
We now know that throughout our existence viruses have woven in and out of life – leaving their stamp on most if not all living things. By some accounts up to eight percent of our genetic material came to us by way of viruses. Yet for all the fear and harm we associate with viruses many (if not most) are phages, infecting bacteria, like those in our microbiome. Genomics is just beginning to reveal the diversity and representations of these entities in nature and within our bodies. But the role that phages can serve as potent antimicrobials is no mystery. As infectious agents of bacteria they are a normal and pervasive component of earth’s flora, and they have already saved countless lives. One day they just might save us or our loved ones.
This is only one solution. There are plenty of others in the works. Lets just hope they get the funding they need in the coming years.
Adapted from  Natural Defense: enlisting bugs and germs to protect food and health (Island Press, Spring 2017.) 

Tuesday, April 12, 2016

Raisin Hell (and Dogs)


20150531_162658 (2)(Cross-posted from toxicevolution.)We were closing in on the end of a glorious spring weekend when my husband discovered the bag. “Any chance you left this lying around — empty?” he’d asked holding the remnants of a one pound bag of Trader Joe’s raisins I’d purchased just the day before with images of molasses filled hermit cookies in mind. I hadn’t, nor had I made the hermits, or chewed away the corners of the bag. Apparently Ella (pictured above) had consumed every last raisin, save the two handfuls my husband snacked on before leaving the bag on the living room floor.
“I bet she won’t be feeling too good later,” he’d said, eyeing the ever expectant dog sitting at our feet, tail wagging, hoping for a few more of the sweet treats. He had no idea. Nor had I. Not really. I’d had some inkling of a rumor that raisins and grapes were bad for dogs, but never paid too much attention. It’s one of those things you hear at the same time you hear of people treating their dogs to grapes. So, to be safe (and feeling a bit sheepish that, as a toxicologist I ought to have an answer to the raisin question) I suggested he call the vet. And that is when we fell into the raisin hell rabbit hole. Five minutes later dog and husband were on their way to the doggie ER, pushed ahead of the mixed breeds and the Golden and the sad-sack blood hound and their people waiting for service.
Meanwhile I took to Google. Was this really a life or death dog emergency? If so, why weren’t we more aware? I get it, that one species’ treat can be another’s poison. Differences in uptake, metabolism, excretion. Feeding Tylenol to cats is a very bad idea (as if you could feed a cat a Tylenol tablet). And pyrethrin-based pesticides in canine flea and tick preventions are verboten in felines. The inability to fully metabolize and detoxify these chemicals can kill a particularly curious cat. But raisins in dogs? Not so clear. Googling will either send you racing off to the vet or to bed. You may even toss your best friend a few grapes for a late night treat, smug in the knowledge that those who have bought into the hysteria are hemorrhaging dollars while paying off the vet school debt of a veterinarian who is gleefully inducing their dog to vomit, while you snooze.
Even Snopes the online mythbuster was confused (though they suggest erring on the side of caution.)20160412_115827
By the time I arrived at the clinic, uncertain enough to follow up on husband and dog, Ella’s raisin packed gut under the influence of an apomorphine injection (a morphine derivative which induces vomiting in seconds) had done its thing.  While Ben and I waited for Ella’s return in the treatment room, somewhat relieved, we played, “Guess how much?”  Treatment with a drug, time with the vet, multiplied by the “after hours factor” this being a Sunday evening after all, we’d settled on something in the $300-400 range.
“Ella did great,” said the vet tech who’d taken her from Ben and hour or so earlier.  “A pile of raisins came up. Some were even still wrinkled!” Phew. Potential disaster averted.  We’d accepted that it’d likely cost a few hundred – but we’d soon be heading home with Ella in the back seat. We had a good laugh about the revisit of the raisins. But the vet tech wasn’t finished. That was just the first step. “So now we’ll give her some activated charcoal,” she continued “and you can pick her up on Tuesday.” Total estimated low-end estimate? A bit over $1000. Paid up front (I have wondered what would have happened if we couldn’t pay – but that is a whole other issue). Apparently we had underestimated the price of a good vomit.
“We can’t be sure we’ve got all the raisins. So we treat with aggressive I.V. Two days is the standard minimum.” Noting our jaws dragging on the floor, or maybe my comment “that’s a plane ticket to Europe” she added, looking at us a bit less sympathetically. Adding “well, of course you can take her tomorrow, or even tonight….if that’s what you want. But that’s what we do. You can talk about it with the Vet.” Or, sure, go ahead take your chances. Poor dog.
Emetics like apomorphine, according to the literature, are only good for purging 40-60% of a dog’s stomach contents. So, even a good barf, will likely leave some raisins behind.
Two days though? With I.V? While waiting for the vet another bout of Googling confirmed the standard treatment. Induce vomiting, charcoal, two days of IV and kidney chemistry panel. Ouch.
But, here is the kicker: no one in the whole Google universe could tell me why we were doing this. Why the fruit we take for granted in our cookies can kill our dogs. The virtual gauntlet thrown, I took the challenge. Surely the scientific literature sitting behind a pay wall would provide the answer. But even in my go to database, the Web of Science a site that normally yields more far papers than I care to even skim their titles – there were a handful of articles. Yet there was evidence of poisonings: one article reported kidney failure in a Shih Zhu and a Yorkie in South Korea.  Another wrote of a Norwegian elkhound, lab, Border collie and a Dachshund all poisoned by raisins. The most popular article, published over ten years ago focused on 43 cases of renal failure following raisin consumption drawn from a decades’ worth of reports to the AnTox database (sponsored by the ASPCA).
That study confirms renal failure following raisin ingestion. Since all dogs in the study were already presenting with symptoms the authors couldn’t provide information on what proportion are sensitive.  Though they acknowledge that there are plenty of anecdotal dogs for whom grapes and raisins are a risk-free treat. They also suggests there is no correlation between amount of raisins ingested and degree of kidney toxicity. In other words there is no dose response. That alone is enough to confound a toxicologist (dose response is a basic tenet of toxicology, the dose makes the poison and all that), and spark controversy amongst dog owners. A dog can eat a few and die. Or eat a whole 16oz bag, and get by with or without treatment depending (albeit with the upset to be expected after eating a heap of dried fruit.) Not only that, but no one know why raisins cause kidney failure. There have been plenty of guesses: fungal toxins; pesticides; something intrinsic to a particular variety; or canine genetics. But there just isn’t enough consistency to identify a mechanism of toxicity. And so vets err on the side of caution.
One vet tells me her dog went into kidney failure after eating some grapes she discarded (she managed to save the dog). Another says she’s never seen a dog with raisin toxicity (of course absence of evidence isn’t evidence of absence – but those dogs who can eat grapes and not die, won’t show up on the vet’s doorstep either.)
“Sorry to hear about your dog’s experience with raisins,” writes veterinary toxicologist John Babish writes after I’ve emailed him about Ella’s ordeal (John was my advisor while in graduate school at Cornell University) asking: what’s up with the raisins?
“The same thing can occur with grapes – all kinds and colors. Canine responses to grapes and raisins are highly variable and some dogs are not affected at all – about 30% are sensitive to very sensitive and a clear majority do okay with no effects. A negative fallout of the inconsistency of response is that some bloggers maintain that grapes/raisins are not toxic to dogs.”  Which explains blogs and websites like the Dog Place posting Snopes and ASPCA Poison Control Urban Legend; Poisoned by Grapes, NOT; Grape/Raisin Debate; or No More Vet Bills,Grapes Toxic to Dogs?
We are not used to uncertainty. We live in a high-tech age of data. We can sequence the human genome and create disease resistant rice. We can measure toxic substances down to the parts per quadrillion (trust me, that’s a really small amount,) and tease apart the inner workings of our cells in detail unimagined even a decade ago. But sometimes you have to make a decision with the information you have. We weren’t willing to bet that Ella was in the majority.
Two days later we collected our pooch, happy as ever and oblivious to the whole ordeal. We won’t ever know (I hope) if she is in the minority of dogs who can’t handle their grapes and raisins; or if that $1000 worth of purging saved her life, or simply emptied our wallet. But, just in case – that replacement bag of raisins I bought? Those will remain on the top shelf hidden away until I get the urge to make some hermits.