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Archive for the ‘Grumpy Toxicologist’ Category

Ok, I’m almost done with HepB, I swear. Just a couple of things that have been bouncing around since I posted the first bit, but haven’t had a chance to cover.

When you google for info on the HepB vaccine, or any vaccine, and include any vaguely negative modifiers (e.g., negative effects, risks, delay, and any disorders under the sun), you end up with gads of hits like mercola.com, or nvic.com, that have a lot of articles that are kind of terrifying. Mercola is outrageously sensational, to the point of being ridiculous, to me at least. NVIC concerns me more, because it has a more even tone – so the misinformation is even more insidious. A couple of the ideas these websites purport in relationship to the HepB vaccine are that it is linked to autism, sudden infant death syndrome (SIDS), and autoimmune disorders.

Autism: the headlines read “Hepatitis B Vaccine triples the risk of autism to infant boys,” in no uncertain terms, and the articles have no discussion of the limitations of the study it’s based on. I read the study, because I’m charitable like that, and here is some additional information. First off, the major findings of the study: the rate of autism in a group of boys who received the HepB vaccine win the first month of life was three times higher than the rate of autism in a group of boys who did not receive the vaccine in the first month of life. Sounds scary, right? Well what isn’t made clear is that the sample sizes are small. The total number of autistic boys considered for that claim was 30. That’s … not very many. The study was a case-control study, which is a particular kind of epidemiological study ideal for identifying associations between disease and exposure; they cannot identifying causality. Additionally, they are ideal for diseases that are very rare. Autism is not particularly rare, at this point, and 30 boys is rather a paltry sample size for such sweeping statements of risk. Additionally, while working on this study, the authors noted that HepB vaccination seemed to exert a protective effective on infant girls, but the sample size is small, so… *shrug*. I draw attention to that only to underscore the absurdity of their headline grabbing claims.

SIDS – I actually can’t find any scientific studies claiming a link between HepB vaccines and SIDS. On mercola.com, this is chalked up to under reporting, and government conspiracy. I can’t argue with crazy, so … I’m sorry if you think there is a government conspiracy. *Head pat* here are some publications talking about how there is no association.

Autoimmune disorders – such as lupus, multiple sclerosis, etc. Now this is actually interesting. Autoimmune disorders occur when the immune system freaks out and starts attacking the body it’s supposed to be defending, in various ways. Scientists don’t fully understand how the immune system ends up getting confused, but there are a couple of popular theories. One theory is based on the fact that some autoimmune disorders are strongly correlated with exposure to a particular antigen, such as with Guillan-Barré and Campylobacter jejuni. This mechanism makes sense – dysfunction of the immune system in autoimmunity is basically an exaggerated, inappropriate response to an antigen, or misdirected response at some autoantigen (some normal part of the body, like peripheral neurons). Molecular mimicry can be the issue here – the autoantigen looks like an actual antigen, and the immune system gets hoodwinked, and over reacts like a crazed toddler. Another theory holds that some host tissue insult causes the body’s immune cells to incorrectly imprint on autoantigens released due to an injury.

So, it kind of makes sense that you could see an increase in autoimmune issues after vaccination – vaccines can cause inflammation, they are designed to elicit an immune response. In some small segment of the population, that response could be overblown or misdirected. Ok so is this correlation actually happening? Well, no, it does not seem to be. There have been some reports of relapse and aggravation in adults subsequent to HepB vaccines, but controlled epidemiological studies have not been able to establish any formal associations (reviewed in Millet et al., 2009).

In summation: HepB vaccines for everyone! Down with hepatitis!

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For ages I’ve wanted to write a post about science and epidemiology of vaccines, the illnesses they prevent, and the adverse reactions that can occur because of them. I am gathering information to finally do this, but it is going to take a lot of time. I’ve spent several hours yesterday and today wading through literature just on one vaccine – Hep B. I think I’m going to do this piecemeal, and then hopefully do a wrap up when it’s all said and done; otherwise, between my actual paying job and my family, it’s never going to happen. I could write books on each of them – people have written books.

My goal here is to try to put the risks of vaccination into perspective with the risks of choosing not to vaccinate. My general disclaimer stands – while I am a scientist, I am not a medical doctor. I am also not an epidemiologist, or a public health professional, or a statistician. I do my best to provide source material for the numbers I give and the statements I make, and if you want me to explain something more, just ask. I am focusing my discussion primarily on incidence data from the U.S.; this is partially because it’s easier for me, and partially because it’s more relevant to the rampant fear of vaccines in this country. My personal stance on vaccines is not the point of this, but you can read more about that here, if you want.

HepB – The Hepatitis B Vaccine

HepB is a three dose series, given at birth, 1-2 months, and 6-18 months (source: CDC vaccine schedule). It reduces the transmission of hepatitis B, a virus transmitted primarily by contact with infected blood and bodily fluids.

In my personal discussions with pregnant moms, I heard a lot of skepticism as to why HepB is routinely administered to all infants, when hepatitis B infection occurs primarily in certain high risk segments of the population – people who have unprotected sex, IV drug users, etc. A lot of people said, well, that’s not me and it’s unlikely to be my child, so why should I put my newborn at risk of an adverse reaction to the vaccine?

Ok, so that’s the rub: the HepB vaccine is incredibly safe. The primary adverse reaction is anaphylaxis (severe allergic reaction to the vaccine), which occurs in an estimated 1 in 1.1 million doses. Anaphylaxis is serious, but treatable – and because the vaccine is administered in a medical setting, the risks are even lower. No deaths have occurred because of the HepB vaccine, in the U.S. or elsewhere. HepB is part of a routine schedule of vaccinations in 179 countries – a LOT of people have been vaccinated (source)!

So what about deaths and adverse outcomes from hepatitis B? Yeah – a LOT. Before the vaccine was introduced in the mid 1980s, annual new hepatitis B infections were increasing rapidly, peaking at 26,654 new cases in 1986 (source). It is estimated that 700,000 – 1,400,000 people are currently infected with the hepatitis B virus, most of whom do not know they are infected (source). Now that HepB vaccine is administered to most newborns and young children, the rate of new infections has dropped dramatically, to 3350 cases in 2010 (source). The number of people in the U.S. who die each year because of hepatitis B infection (as in, the official cause of death) is hovering around 1700 for the last few years (source).

Most of the deaths from hepatitis B are in older people – that is, not infants dying of acute infections. Hepatitis B can cause a serious acute infection, or a chronic illness. The chronic infection and resulting liver inflammation can lead to cirrhosis and cancer – hepatitis B is one of the leading causes of primary liver cancer. So, when an infant is vaccinated, it reduces the transmission from mother to infant, as well as reducing the rates of subsequent infection later in the child’s life. As more generations of infants and children are vaccinated with HepB, the rates of hepatitis B incidence and related deaths will continue to drop.

To sum up, hepatitis B kills thousands of people every year, while the vaccine kills ZERO. Hmm.

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When I was in graduate school, I spent a semester as a teaching assistant in an introductory public health course. My duties consisted primarily of proctoring exams and leading discussion groups, but I also attended the class, mostly sitting in the back and working on my dissertation during lectures. One day, I heard the instructor, who was then heavily pregnant with her first child, begin her lecture by asking for a show of hands – who here was planning on vaccinating their children? My ears perked up immediately, as this has always been a pet subject of mine. She went on to say that she wasn’t sure, herself; shed been hearing a lot about their link to autism. Then, hand to god, she showed a YouTube video of Andrew Wakefield, proselytizing about the dangers of vaccinations. To a public health class of college freshman.

* * *

Vaccinations are the hill that I will die on, the line in the concrete, the one thing I refuse to even debate. The subject my familiars know not to bring up, not least because there is a sign that says as much in my kitchen. The thing I cannot listen to differing opinions about, because I don’t think it’s in the realm of opinion. I think it is black and white, right and wrong.

I probably shouldn’t write a word about it, but it’s a central tenant of my existence. There is a very VERY limited set of scenarios in which it is acceptable not to vaccinate. It includes people who have had serious reactions to specific vaccinations, and people who are immunodeficient in specific ways.

The efficacy of vaccinations is based on the principle of herd immunity – that, if a certain proportion of the population is immune to a communicable disease, the remainder of that population is extended some measure of immunity simply because the pathogen cannot find enough vulnerable bodies to infect.

So when someone chooses not to vaccinate their child for personal reasons, that choice can affect entire communities and populations. Herd immunity is compromised. The most vulnerable people – infants and children too young to be vaccinated, or those who are medically unable – suffer the greatest consequences, as these (preventable!) illnesses are much more serious, even deadly, for them. So – when someone chooses not to vaccinate, not only are they relying on herd immunity to cover their child’s ass, they are endangering everyone else’s kids too.

I cannot believe that this is still a topic of discussion. The autism bullshit has been so thoroughly debunked, even the media slowly (so goddamn slowly) seems to have cottoned on. And yet, there is a pertussis EPIDEMIC in my state. People (BABIES) have died. Totally preventable. Makes me sick.

And one of reasons it makes me so viscerally upset is that I know that, at least to some degree, the blame lies with the scientific community. Not just the quacks (Wakefield et al.), but the rest of us too. For failing to communicate effectively, failing to make bold statements. Scientists hate to make definitive statements – it’s not scientifically accurate to claim something is wholly true or false. Rather, we say that “evidence suggests” or “no significant elevation was observed” or something that sounds similarly evasive or inconclusive to the layman’s ear.

That basic misunderstanding between scientists and laypeople, mixed with a sensationalist media and a litigious society is a recipe for disaster. Or a pertussis epidemic, I guess.

Here are some infographics that help communicate some of the issues surrounding vaccinations:
http://thumbpress.com/the-immunization-debate-infographic/
http://www.good.is/post/infographic-vaccination-nation/
http://www.jhsph.edu/research/centers-and-institutes/ivac/resources/vaccine-cost-effectiveness.html
http://www.behance.net/leon_farrant/frame/2878481

And here is a fantastic book recommendation:
Autism’s False Prophets: Bad Science, Risky Medicine, and the Search for a Cure, by Paul Offit (amazon).
Offit has another book out that I’m psyched to read, but I gotta finish Broken Harbour first. You know how it is.

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This is the next installment of Snoozical Rambles about Toxicology, which may or may not becomes a weekly theme.  If you are new here, you should go read my disclaimer.  

Today, I’m all jazzed about artificial sweeteners, specifically aspartame.  This is a subject near and dear to my heart, which is to say: don’t fuck with my diet coke, man.  More often than not, when people find out I’m a toxicologist, they give me the side eye and ask me why I’m drinking that diet soda because don’t I know that aspartame will make holes in my brain or give me cancer etc.??

Nope!  No it won’t!  Aspartame is so, so, SO non-toxic.  “But wait! Susie, you said before that the dose makes the poison! And I’ve seen you down a two liter in one evening!”  Yes, you are correct – the dose DOES make the poison – and aspartame doesn’t become a poison unless you are drinking ridiculous volumes.  Here are some numbers: the FDA acceptable daily intake (ADI) for aspartame is 50 mg per kg of body weight.  That equates to over 3 grams of pure aspartame per day for a 135 pound human, on up to 4.5 g for a 200 lb person.  There are about 125 mg of aspartame in a 12 oz can of diet coke, my drink of choice – so that’s about 10.4 mg per ounce.  In order to reach my daily limit of aspartame, I’d need to drink nearly 300 ounces of diet coke.  In a day. I’ve tried, I’ve done some serious focused work, and the most I’ve ever had in a day is two 2 liters.  That’s ~135 ounces. I had to use a bendy straw, and I had several people cheering me on.

Ok, so maybe you’re thinking, wait, that’s not that far from the limit! 135/300, that’s almost halfway there! Right, so that 300? That is equivalent to the 50 mg/kg/day FDA ADI.  That number is health protective, i.e., well below an exposure that could be expected to cause any toxicity in humans – you could ingest that much, every day, for your whole life and experience no health effects.

The ADI is based on a LOT of science: a host of epidemiological studies of humans, as well as long term exposure studies in animal models.  Taking the animal studies first: the National Toxicology Program, an actual reputable research organization, conducted life time exposure studies in rodents  with daily intakes spanning

In acute studies in rodents, no effects were observed at doses exceeding 10,000 mg/kg.  That’s the equivalent of a rat pounding 20 cans (240 oz) of diet coke at once.  Or a human drinking 5600 cans of diet coke. THAT IS A LOT OF DIET COKE, even for me. In chronic, lifetime cancer bioassays in rodents, they fed doses up to 12,000 mg/kg/day for periods up to two years (the lifetime of most rodents), and were unable to detect effects.  NO EFFECTS.  You have to believe me when I say that this INSANE – laboratory rodents LOVE getting tumors, and they just WOULDN’T DO IT.

Epidemiological studies in humans have been similarly boring – no effects, no significance, nothing, nothing.  There was one by Olney et al. (1996) that tried to correlate aspartame with brain tumors, but that study has been roundly dismissed due to wonderful, ethical things like fudging and misrepresenting data. Every other study, and there have been MANY, has found no effects. NO EFFECTS.

Aspartame: the least toxic substance ever, except maybe water.

All the cold hard facts (numbers) in here came from the 2007 Safety Evaluation by B.A. Magnuson et al.  Here is the evaluation summary, and here is the evaluation itself (though you’d have to pay or have journal access to read it).

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