Skip main navigation

Chemicals are present in foods and drinks that shouldn’t be there

Chemicals are present in our foods and drinks that should not be present. Where could they possibly come from ?
A cartoon with our avatar whose name is Shopper-Vicky, pushing a supermarket trolley. This represents the consumers.
© University of Turin

Chemicals are present in our foods and drinks.

When we eat a good meal, we can certainly comment “excellent” or “well cooked” or “well garnished”, etc. But we are not able to taste the presence of molecules present at low doses. Our mouth is full of receptors for many natural chemicals, and resembles and works like an analytical chemical instrument: the main job is to detect all pleasant components in food/drink, as well as those potentially dangerous. The sensitivity of our natural instrument, the mouth, is not suitable to detect low doses of chemicals and this is why we can get ill with poisonous mushrooms.

Chemicals present in foods/drinks that are not meant to be there take the acronym of NIAS, which stands for Not Intentionally Added Substances. These substances are not declared on the label among all the ingredients and additives (including colorings, preservatives, antioxidants, etc.) because they are not supposed to be there.

Oh, Hi Shopper-Vicky. Do you have a question?

YES, I’d like to know where these chemicals come from.

By the way, Shopper-Vicky is our avatar representing consumers.

NIAS are molecules that are generated naturally or artificially in some step of the food production and processing chain. Indeed they can originate from the spontaneous decay of a natural or non-natural substance, from its bacterial biomodification or perhaps they are contaminants from the initial producer (think about pesticides, herbicides, veterinarian medicines, animal food supplement, etc).

Let’s also think about the industrial processes, all those huge machineries which manipulate food and drinks: they may use specific coating products, may not be perfectly cleaned, or their surfaces might not be totally inert. After all, also these machines can be considered FCM, and thus chemicals from the processing chain can evidently end up in the final product.

During transportation from producers to retailers, light, heat and mechanical stress can promote the chemical modification of substances present in packaging and in food. Many chemicals are not fully stable when subjected to light, heat, non-neutral pH.

In addition, another class of molecules to be kept under control are those implicated in packaging-to-food migration. Migration is defined as the ability of a chemical to “jump” from the packaging (or other origin) to what’s packaged inside, our food/drink. Let’s give you some example:

Plastic water bottles Water plastic bottles are everywhere and are used by billions of people, they are often made of PET (Polyethyleneterephthalate). Migration occurs when the container loses small amounts of PET or of terephthalic acid – which is used as plasticizing agent.

Pan cooking In our kitchenware the anti-adherent coating can turn us into a skilled chef. There are however some concerns in the usage of low-quality, cheap anti-adherent kitchenware, since the coating is a thin layer of silicone or PTFE (Polytetrafluoroethylene), or other chemicals. If the process of coating during pan production is not perfect, at high temperatures a minimal amount of PTFE polymer (or other chemicals) leaves the coating and migrates into cooked food.

Microwavable plastic packagings Also in this case the heating has a key role. There are lots of microwave readymade dishes that can be heated quickly in the microwave oven, but since the plates are made of plastics their chemicals can migrate. Such a release must be monitored, controlled and minimized.

Assessing migration by quantitating these chemicals, prior and after contact and cooking, is the only way to get to know the phenomenon. Analytical chemistry becomes essential. At the top of this article we told you about our mouth as a chemical instrument, its receptors and its analytical role in protecting us. You have understood that our mouth is not sensitive enough for detecting the chemicals which are only present in trace amounts.

Sensitivity is the capability of detecting small quantities of a substance: this is a key factor in analytical chemistry and it is linked to the concept of selectivity: the capability to discriminate between analytes. An instrument capable of good sensitivity and high selectivity is ideal for analytical quantitation, which is then required to determine the concentration of a given chemical in our meal.

Concentration is the ratio of the amount of a chemical species over the total volume of a liquid solution which contains it. Concentration is often expressed as weight/volume, as reported by the agency IUPAC (International Union of Pure and Applied Chemistry).

In biological and toxicological fields, the concentration takes a slightly different meaning, mostly oriented to its activity. The concentration of a medicine in a living organism as a pure chemical measurement is not informative about its beneficial or toxic effects, since our body reacts in different ways to different chemicals. Instead, we should rather talk about the bioactivity of a medicinal drug.

Can we avoid migration? Current knowledge indicates that tollal prevention is unlikely. There will always be a trace of FCM molecules in foods/drinks. So the real question is: are these traces potentially unhealthy? This is the question that scientists are trying to answer for each chemical substance. Before running into conclusions, we should have a more complete knowledge.

© University of Turin
This article is from the free online

Consumer and Environmental Safety: Food Packaging and Kitchenware

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education