Tuesday, 24 January 2017

Acrylamide: FSA Concerns May Well Be Half-Baked.

I arrived at work today to encounter several colleagues discussing the risk eating roast potatoes and overcooked foodstuff like toast posed to developing cancer. I jumped to an immediate conclusion that a tabloid news outlet, likely the Daily Mail, had misrepresented a study in some way. As the day went on I discovered the BBC were also running the story without a hint of cynicism and was shocked to discover that the source seemed to be the UK food standards agency (FSA) themselves. The elevated cancer risk is attributed to the concentration of acrylamide in foods cooked at high temperatures, with foods such as burnt toast and roast potatoes being of particular concern. This isn't the first time the compound has been linked with cancer, but it's usually by alternative health websites such as Daily Health Post. For a serious and well-regarded organisation to be repeating these claims, there must something to them... Right?
The New Scientist gives us this description of acrylamide:
"Acrylamide is made by something called the Maillard reaction, which browns cooked foods and gives them their pleasing flavour. As sugars and amino acids react together, they produce thousands of different chemicals. Particularly high levels of acrylamide are found in starchy foods, like potatoes and bread, when cooked at temperatures over 120 oC. In the body, acrylamide is converted into another compound, glycidamide, which can bind to DNA and cause mutations."-New Scientist
Acrylamide has been considered a potential cancer risk for some time so one may ask why the sudden concern? What evidence does it have that acrylamide poses a more serious health than previously believed?

The FSA website states:
"Biological effects of acrylamide exposure include cancer and damage to the nervous and reproductive systems. Most of the evidence is based on effects seen in experimental animals or cells studied in a laboratory. Whether or not acrylamide will cause these effects in humans will depend upon the level of exposure."
The strongest link between acrylamide and cancer thus far, has been found in studies concerning rodents, not humans. This is an area of confusion to the public and concern to science, as it's very tricky to extrapolate results from animal studies to human beings. Firstly animal research is often very poorly conducted and reviews and summaries of methodologies and results have been found to be inadequate in many cases.  Key problems with animal studies are summarised in a 2004 study by Pandora Pound et al published in the BMJ:

  • Disparate animal species and strains, with a variety of metabolic pathways and drug metabolites, leading to variation in efficacy and toxicity
  • Different models for inducing illness or injury, with varying similarity to the human condition
  • Variability in animals for study, methods of randomization, choice of comparison therapy (none, placebo, vehicle)
  • Small experimental groups with inadequate statistical power; simple statistical analyses that do not account for confounding; and failure to follow intention-to-treat principles
  • Nuances in laboratory technique that may influence results, for example, methods for blinding investigators, being neither recognized nor reported
  • Selection of outcome measures, which being surrogates or precursors of disease, of uncertain relevance to the human clinical condition
  • Variable duration of follow up, which may not correspond to disease latency in humans
    -(Pound, et al, BMJ, 2004)
So there's a very pertinent question of whether animal research can be extrapolated to humans based on both biological differences and methodological flaws in the studies themselves, but even putting this aside, do the studies that FSA reference even suggests what the body has inferred?
" EFSA published its first full risk assessment of acrylamide in food, which confirms that acrylamide levels found in food potentially increases the risk of cancer for all age groups."
The FSA statement above seems to be based on one study from the European Food Safety Authority, Scientific Opinion on acrylamide in food (Working Group on Acrylamide in Food, 2015) does indeed show a higher risk of cancers in rats and mice exposed to acrylamide, but the level of exposure is far greater than that in the human diet. The paper gives us relevant levels of exposure. High human consumption is stated as up to 3.4 µg/kg b.w. per day, whilst mice showing signs of neoplastic effects were exposed to 0.17 mg/kg b.w. per day. In other words, the rodents were exposed to up to 50 times what even a high consumer of acrylamide, referred to as AA in the report, would be exposed to.

The report concludes
"The Panel concluded that the current levels of dietary exposure to AA are not of concern with respect to non-neoplastic effects... the epidemiological associations have not demonstrated AA to be a human carcinogen..."
But also the margins of exposure may mean a greater risk in the industrial uses of acrylamide. The paper also suggests the need for more research into the human effects of dietary consumption of acrylamide.
"Evidence from human studies that dietary exposure to acrylamide causes cancer is currently limited and inconclusive."
Contrast this with what the FSA are telling the British public the study and the EFSA conclude about acrylamide and it's actually quite shocking.

 Have any studies been conducted with regards to acrylamide and cancer occurrence in humans and what have they found, if we are disregarding animal studies? Yes, in Sweden in 2003 and the FSA reference that too. And again they don't exactly get the contents of the study correct.The study, Dietary acrylamide and cancer of the large bowel, kidney, and bladder: Absence of an association in a population-based study in Sweden (Mucci, et al, 2003) published in the British Journal of Cancer states in its conclusion:
"We found reassuring evidence that dietary exposure to acrylamide in amounts typically ingested by Swedish adults in certain foods has no measurable impact on risk of three major types of cancer. It should be noted, however, that relation of risk to the acrylamide content of all foods could not be studied."
The FSA are conducting their own research regarding acrylamide and it all pertains to studying which foods contain the highest concentrations and how to reduce this factor in cooking. None of it seems to be focused on establishing a strong causal link between acrylamide and cancer. They tell us, in their "Go for gold" initiative, for instance, to toast our bread to golden rather than brown, but give no indication of the different concentrations of acrylamide in the different states of toast. I doubt there's a difference of a factor of 50 in a golden piece of toast and even a charred piece, the factor which the study they cite is indicative of elevated cancer risk. That's if we're to take that study at face value which they clearly have!

So, what's the issue here? Acrylamide may well cause cancer and more research is definitely needed, maybe cutting down isn't such a bad idea. The problem is that scare stories such as this turn the public off to science. There's a general perception of scientists as lofty, aloof and removed from the general public, passing down decrees about what foods should and shouldn't be consumed. Scares stories like this are also used to downplay the risk of factors which have been conclusively shown to cause cancer. In her statement to the press regarding this issue Emma Sheilds of Cancer Research UK attempts to refocus the debate on these issues:
“Although evidence from animal studies has shown that acrylamide in food could be linked to cancer, this link isn’t clear and consistent in humans. It’s important to remember that there are many well-established factors like smoking, obesity and alcohol, which all have a big impact on the number of cancer cases in the UK,”