Exposure to acrylamide and trace metals in food: still a cause for concern

What are trace metals and why are they found in our food?

Morgane Champion: Many trace metals, some of which are better known as "heavy metals", are found in our food: cadmium, lead, mercury, nickel and so on.

Why? Firstly because they occur naturally in the environment. For example, cadmium is found in soil and easily penetrates plants through their roots. But also because human activities – agriculture, industry, road traffic, etc. – use or produce trace metals, which then end up in soil, water or air.

In this first part of TDS3, we studied five trace metals – silver, cadmium, lead, aluminium and mercury – as well as acrylamide. The results on our dietary exposure to other trace metals, such as cobalt and nickel, will come later. 

The presence of certain contaminants in food has fallen compared with the results of previous TDSs. Does this mean that the situation is improving?

Véronique Sirot: It's true that TDS3 did actually show a reduction in the average concentrations of acrylamide, silver, aluminium, cadmium and lead in food. 

However, this was not the case for all foods. In fact, increases were observed in certain food groups. This was the case, for example, with certain cereal-based products such as bread, sweet biscuits, fine bakery wares, pasta, etc. These are the foods that contribute most to our dietary exposure to aluminium, cadmium and lead. Concentrations of these contaminants in certain vegetables have increased, although this does not call into question the indisputable nutritional benefits of eating them. On the other hand, sweet biscuits and fine bakery wares, as well as being contaminated with certain trace metals and acrylamide, have little nutritional benefit.

Furthermore, for most of the contaminants studied in this first part, the conclusions of the population risk assessment remain the same as those formulated in TDS2: exposure to acrylamide, cadmium, lead, aluminium and methylmercury is still too high for all or part of the population.   

What are the new results for mercury?

Morgane Champion: More detailed analysis has enabled us to rule out the risk associated with inorganic mercury, whereas it had not been possible to reach a definite conclusion in TDS2. 

With regard to methylmercury, which is mainly found in fish of all kinds, contamination and exposure levels were similar to those observed in TDS2. Predatory fish at the end of the food chain, such as tuna, have the highest concentrations of methylmercury. However, consumption of fish has undeniable nutritional benefits. To optimally meet nutrient requirements, we recommend eating two servings of fish a week, including one of oily fish, while varying the species and source of supply. Any species of fish can be consumed, as long as these recommendations – which limit the risk of overexposure to methylmercury – are followed.

Is water still a major source of lead exposure?

Véronique Sirot: Dietary exposure to lead has fallen by an average of between 27% and 41% in children and between 37% and 49% in adults compared with TDS2, which is good news. This clearly shows the effect of public health policies that have been in place for many years now, such as the ban on lead in petrol, water pipes and paint, etc.

While water is still a major contributor to our exposure to lead, it is not the only one: bread and vegetables also play a part, as well as alcoholic drinks for adults. 

What foods contain acrylamide and why is it a problem?

Morgane Champion: Acrylamide is not a trace element. It is a heat-induced organic compound that appears during high-temperature cooking processes (above 120°C) such as frying or roasting. Acrylamide is formed in foodstuffs rich in starch or certain other sugars, or in certain amino acids such as asparagine. French fries, sautéed potatoes, crisps and biscuits are the foodstuffs most likely to be contaminated with acrylamide.

Compared with TDS2, we have seen a decrease in average acrylamide concentrations for the foods that were the most contaminated and the main contributors to exposure. This was the case for coffee, in which acrylamide is no longer detected. 

These reductions seem to reflect the effectiveness of the mitigation measures taken by the food sector in recent years to reduce the presence of acrylamide in foodstuffs. However, consumer exposure remains too high. Efforts therefore need to continue to reduce concentrations in food, particularly in French fries and sautéed potatoes, which, as well as being of little nutritional value are the main contributors to our exposure. 

Cadmium contamination of food has been in the news recently. What did you actually find?

Véronique Sirot: The main food groups contributing to cadmium exposure were similar to those identified in TDS2: bread and other wheat-based products such as pasta, fine bakery wares, cakes and biscuits, as well as potatoes and vegetables, and, for those who eat them regularly, molluscs and crustaceans. 

We will shortly be publishing an expert appraisal detailing the population's overall exposure to cadmium, not just that due to food. This work will prioritise the actions to be taken to reduce cadmium contamination of the French population. 

What happens next?

Morgane Champion: These initial results form part 1 of TDS3. The parts on the other food contaminant groups will be published over the next few years. These include other trace elements, substances from food contact materials such as bisphenols and phthalates, pesticide residues, PFAS, etc. For each group, we will be formulating specific recommendations aimed mainly at reducing exposure to contaminants.