This would be equivalent to 182 micrograms for a 70 kg human as a tolerable daily intake (TDI) for carcinogenic levels. The TDI for neurotoxicity was found to be higher, at 40 micrograms per kg per day, or 2,800 micrograms per day for a 70 kg human.
Both levels vastly exceed levels estimated by various national agencies or studies. Health Canada, for example, estimates the average exposure of adults to acrylamide in food to be between 0.3 and 0.4 micrograms per kilogram of body weight per day, while a study from Sweden estimated intakes of about 0.5 micrograms per kilogram of bodyweight. The US Food and Drug Administration (FDA) estimated intakes to be around 0.4 micrograms per kilogram of bodyweight per day.
The study, funded by the Grocery Manufacturers Association (GMA), used a state-of-the-art physiologically-based toxicokinetic model to compare doses of acrylamide and its metabolite glycidamide in humans and rats.
The researchers, led by Robert Tardiff from the Sapphire Group Inc. in Bethesda, Maryland, report their findings in Food and Chemical Toxicology.
“Overall, we conclude that the TDIs and margins of exposure for average exposures to acrylamide in cooked foods provide an adequate margin of safety to preclude neurotoxicity as well as tumor formation,” wrote the researchers.
“The certainty in our conclusions is relatively high because of reliance on relying on findings from our updated human internal dosimetry model and a reasonable understanding of acrylamide’s modes of action,” they added.
Acrylamide is a suspected carcinogen that is formed during by heat-induced reaction between sugar and an amino acid called asparagine. Known as the Maillard reaction, this process is responsible for the brown colour and tasty flavour of baked, fried and toasted foods.
Despite being a carcinogen in the laboratory, many epidemiological studies have reported that everyday exposure to acrylamide in food is too low to be of concern.
The compound first hit the headlines in 2002, when scientists at the Swedish Food Administration first reported unexpectedly high levels of acrylamide, found to cause cancer in laboratory rats, in carbohydrate-rich foods.
Since the Swedish discovery a global effort has been underway to amass data about this chemical. More than 200 research projects have been initiated around the world and their findings co-ordinated by national governments, the EU and the United Nations.
Source: Food and Chemical Toxicology
Published online ahead of print, doi: 10.1016/j.fct.2009.11.048
"Estimation of Safe Dietary Intake Levels of Acrylamide for Humans"
Authors: R.G. Tardiff, M.L. Gargas, C.R. Kirman, M.L. Carson, L.M. Sweeney.