Whether it’s freshly harvested or artificially processed, much of the food we eat is chemically contaminated in some way. There are various types of chemical contaminants, but some common examples include mycotoxins, heavy metals (e.g. lead and mercury), acrylamide, and organic pollutants like dioxins.
While the chemical contamination of food may sound alarming, in most cases the contaminant is present at such a low level that it doesn’t pose a risk to human health. In fact, the way food is processed, handled, stored, and transported means some chemical contamination is almost inevitable.
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Environmental and food processing factors
Chemical contamination can occur as a result of various environmental factors, such as the location of the farm or body of water from where the food is harvested. The location determines what type of contaminants are potentially present in the area. For example, if the farmland is near an active volcano, the soil may be contaminated with volcanic ash particles.
Agricultural treatments like fertilisers, pesticides, and herbicides are another common cause of chemical contamination. Even if crops are washed and cleaned after they’ve been harvested, residue from these agricultural chemicals may still be present on the surface.
The way food is processed after it’s been harvested or slaughtered can also result in some contamination. The type of contaminant depends on what the food and the processing method are. For instance, meat may be cross-contaminated with bacteria during the freeze-drying process if the freeze-drying chamber hasn’t been cleaned properly. On the other hand, chemicals such as synthetic vitamins, antibiotics, and metabolites might already be present before the meat is even processed.
Regulatory measures on food contamination
The specific laws that regulate the food industry vary depending on the country or region.
However, there are international standards and industry best practices on which these laws are based. Strict protocols exist for each of the following stages:
- Farming
- Harvest or slaughter
- Processing
- Packaging
- Handling
- Storing
- Transporting
- Cooking
In the UK, several laws and regulations govern various aspects of food safety and food production. They include the following:
- The Food Standards Act 1999 – The main purpose of this law was to establish and define the functions and powers of the Food Standards Agency. It’s designed to ensure businesses comply with the regulations on food safety.
- The Food Safety Act of 1990 – This provides the framework for all food legislation in England, Wales, and Scotland. It regulates the activities of businesses that are engaged in food production and preparation. The Act includes provisions on the nutritional value of food, advertising and labelling, and quality assurance.
- Northern Ireland Food Safety Order 1991 business guide – This is an order issued by the Food Standards Agency and applies to businesses engaged in food in Northern Ireland. It covers various aspects of the food distribution chain, from harvest to food catering.
- European Council regulations – A collection of regulations relating to food production among EU members. Some of the standards, such as the acceptable levels of contaminants, have also been adopted by the UK government.
Harvesting & processing
Various regulations mandate that fresh produce must be thoroughly inspected and cleaned before being sold to the public. These protocols start with the harvesting of food products such as meat and grains. Some fresh food may also need to be treated with chemicals or radiation to ensure there are no parasites or pathogens present.
Storage & handling
Strict protocols on hygiene and safety must be followed when storing and handling food. These include making sure the facility is cleaned to the required standard and implementing approved packaging methods. For example, some types of food must be stored at a certain temperature or vacuum-packed.
Storage & transport
All food, whether it’s fresh produce or processed goods, must be transported correctly. Any containers and trucks that are used to transport food and drink products should be cleaned and sanitised regularly. Even if the proper protocols are followed, there’s still a small chance that any residual chemical pollutants in the lorry or container may contaminate the food.
What is chemical contamination?
Chemical contamination is the unintended addition or presence of unnecessary chemicals in places where they shouldn’t be. When it comes to food, chemical contaminants can range from non-harmful ingredients to toxic substances.
There are several reasons why food may be contaminated with chemicals:
- Synthetic vitamins and hormones haven’t been completely metabolised or excreted by livestock
- There are traces of pesticides and fertilisers
- Environmental pollutants such as microplastics have been absorbed by cells
- Cross-contamination has occurred due to unhygienic practices
- Proper protocols for processing and handling food haven’t been followed
- The packaging has been damaged or punctured
Health implications
Unlike biological contaminants, chemical contaminants can’t be destroyed by normal cooking methods. In some cases, cooking may even exacerbate the problem.
The health implications of chemical contamination can either be acute, chronic, or neutral – it all depends on the type of chemicals involved, their concentration and toxicity. Some chemicals can immediately cause a severe allergic reaction, while others may lead to chronic disease if someone is exposed to the contaminant over the long term.
Examples of chemical contamination of food
The chemical contamination of food is virtually inevitable; there will almost always be some trace of unintended chemicals, whether it’s fresh produce or processed food. These contaminants can be organic or inorganic and either compounds or elements.
Although many of them are non-toxic, some pose a danger to human health – especially when they’re above a certain level. That’s why these types of chemicals have an acceptable threshold of concentration as contaminants in food. Here are some examples:
Heavy metals:
- Lead – 1.5mg/kg
- Cadmium – 1.0mg/kg
- Mercury – 0.5mg/kg
Polycyclic aromatic hydrocarbons:
- Benzo(a)pyrene – 5.0µg/kg
- Sum of benzo(a)pyrene, benz(a)anthracene, benzo(b)fluoranthene and chrysene – 30.0µg/kg
Dioxin and dioxin-like PCBs:
- Sum of dioxins – 3.5pg/g wet weight
- Sum of dioxin and dioxin-like PCBs – 6.5pg/g wet weight
- Sum of PCB28, PCB52, PCB101, PCB138, PCB153 and PCB180 – 75ng/g wet weight
Chemical contaminants can also be classified based on their source:
- Industrial chemicals – these include precursors, reagents, solvents, and cleaning agents. There’s a chance these chemicals may contaminate the raw food ingredients or the finished product itself during the processing, packing, and storing stages.
- Agricultural chemicals – although fresh produce like fruit, vegetables and milk are generally considered healthy, they’re still exposed to various toxic agricultural chemicals (herbicides, fertilisers, insecticides etc.). This is why it’s important to wash fruit and vegetables before eating them. Even after they’re cleaned, traces of toxic chemicals may remain on the surface.
- Preservatives – these chemicals are intentionally added to food to extend their shelf life and include sulphites, nitrates and benzoates. However, they can become contaminants if they’re present in excess amounts or are accidentally added to food products when they shouldn’t be.
- Naturally occurring toxins – these are biochemical substances that are naturally present in living organisms. They’re often produced by marine organisms like pufferfish, crabs and shellfish as a means of protection against predators.
What are some ways to keep chemicals from contaminating food?
Although some chemical contamination is almost unavoidable, there are things you can do to minimise the risk. These tips generally apply to consumers or home food preppers and include the following:
- Properly label food and chemical containers
- Ensure packaging is tightly sealed or transfer food to containers with lids
- Wear protective gear such as gloves when handling or preparing food
- Follow the manufacturer’s instructions when preparing food
- Avoid storing acidic food in metal containers
