Article by Athini Amarasiri.
What is a Chemical Contamination in Food?
Chemical contamination refers to substances that are not a natural part of the food and may be poisonous. They may have contaminated the food through carelessness or poor handling, the environment, equipment, or from natural sources. They include toxins, dangerous chemicals and residue of excess chemicals used in food processing.
Examples of a chemical contamination:
- Antibodies, food additives
- Disinfectants, detergents, sanitisers
- Food allergens
- Heavy metals such as mercury, zinc, cadmium, lead
- Mycotoxins, marine toxins
- Pesticide, insecticide, fertiliser residues
Chemical contamination of food is possible at any point of the food chain from farming of the food materials to the final production of the packaged finished product.
Chemicals are often used for various useful purposes throughout the food chain. For example, pesticides on crops, sanitisers in food manufacturing facilities or food additives in food production. When used at the correct dosage and when following the required procedures, the use of chemicals can be beneficial to the food. Chemicals become a hazard when inadequately or negligently used.
Within the FSANZ Code, the following schedules offer limitations to residues:
- Schedule 19 Maximum levels of contaminants and natural toxicants
- Schedule 20 Maximum residue limits
- Schedule 21 Extraneous residue limits
There are three main types of chemical hazards:
- Naturally occurring chemical hazard
- Intentionally added chemical hazards
- Unintentionally added chemical hazards
 Naturally Occurring Chemical Hazards
Naturally occurring chemical hazards are toxins produced by plants, animals or microorganisms. Despite their origin, they are usually considered as chemical hazards to distinguish them from microbial hazards such as bacteria, yeast, mould and viruses. They usually enter the food before or during harvest, but they can reach hazardous levels due to inappropriate storage conditions.
The common naturally occurring chemical hazards are:
- Aflatoxins associated with peanuts, maize, tree nuts and certain spices
- Poisonous neurotoxins in mushrooms
- Scrombotoxins in fish
Currently, food authorities are studying the health risks associated with Ochratoxin A in food.
Food allergens are also identified as chemical hazards in food which can cause dangerous reactions in people who are susceptible.
Within HACCP plans allergen risks assessments are normally separated from chemical risks assessments.
To the left are the 10 allergens that food within Australia must be clearly labeled with. This poster can be downloaded from the FSANZ website.
 Intentionally Added Chemical Hazards
Chemicals are intentionally added to food to achieve certain properties of the food. It is important that food manufacturers correctly add these chemicals at the appropriate dosage to prevent a chemical contamination.
Chemicals used in food production may include:
- Food additives
- Any other chemical added as a part of the finished product formulation. g.: Vitamins
There are two aspects that these chemicals become potentially hazardous.
- If the chemicals are added to food that are beyond the acceptable limits established by FSANZ.
E.g. High level of sodium nitrite, Vitamin A, sulfiting agents
This can lead to cause reactions in people who are sensitive to these chemicals.
- If the chemicals are used inadequately, the safety of the food product might be compromised.
E.g. If a preservative is added to stop the microbial growth, only the right quantity would serve the purpose. If the right quantity of the preservative is not added, microbes would continue to grow, and the food product can be unsafe to consume.
 Unintentionally Added Chemical Hazards
These are the chemicals that can accidentally contaminate the food during
processing. Unintentionally added chemical hazards include:
- Drug residues in animal products. g.: Antibiotics
- Environmental pollutants
- Heavy metals in food produce from growing soil, water
- Industrial chemicals, such as machinery lubricants
- Pesticides in crops
- Residues after the cleaning and sanitising process
These chemical hazards can prevent or reduce to the acceptable level by adopting a food safety management system.
How to Control Chemical Hazards?
Chemical hazards can be screened, or ingredients may be tested by an approved laboratory. If the food manufacturer follows good manufacturing practices, chemical hazards can be prevented or controlled.
Chemical hazards should be addressed in every step of food processing:
- Storage of chemicals (cleaning agents, sanitisers, dangerous chemicals)
- Receival (raw material and packaging material)
- During processing (avoid cross contamination)
- Finished products (storage and transport)
Care must be taken by the food manufacturer to ensure all the chemicals used in and around the facility meet the required specifications.
Proper storage and handling practices play a vital role in controlling chemical hazards. The most effective chemical hazard control is prevention. Establishing an effective chemical control program in the food manufacturing facility can reduce chemical hazards in food to an acceptable level or eliminate chemical hazards in food.
Effective Chemical Control
- Conduct frequent audits and reviews on current procedures of chemical use
- Ensure food-contact packaging is fit for the food industry
- Ensure there is a cleaning and sanitising process after machinery maintenance
- Establish an approved supplier program to minimise introduction of chemical hazards into the facility
- Label or colour code containers and tools used to handle chemicals and ensure that they are used only for the chemicals
- Maintain an inventory of all chemicals
- Maintain good storage practices
- Perform adequate inhouse testing and quality inspections
- Pest control should be performed by professionals and chemicals in use fit for the food industry
- Provide adequate and regular employee training on safe handling of chemicals
- Provide procedures on how to use cleaning and sanitising chemicals
- Regularly evaluate the recipes to ensure that they meet most updated regulatory requirements including restricted ingredients and additives, and labelling requirements
- Store allergens separately from non-allergens
- Store chemicals separately from food, packaging materials and food contacting surfaces
- Use approved chemicals fit for the food industry
- Use designated tools for handling allergens
Download me: Chemical Hazards ed 01 – 21-05-20