A “may contain” statement is the most over-used sentence in food labelling. Applied properly it is a risk communication that lets an allergic consumer make an informed decision. Applied as a blanket disclaimer it does the opposite: it removes choice from the people it claims to protect, and it tells an auditor that you have not validated your own cleaning.
The difference between the two is a number. If you cannot produce one, the statement is a guess with legal wording around it.
When precautionary labelling is justified
Precautionary allergen labelling is justified only where a real cross-contact risk remains after your controls have been applied and validated. Three tests, in order:
- Is the allergen actually present on the line? If nothing in the facility contains it, there is no risk to communicate, and a statement invents one.
- Have the controls been applied and validated? Segregation, sequencing, dedicated equipment and a validated clean come first. A precautionary statement is not a substitute for any of them, and it is not a cheaper alternative to fixing a changeover.
- Is the residual cross-contact above the action level for this product? This is the quantitative step, and it is where most programmes stop short.
Reference doses: what the numbers mean
A reference dose is the amount of allergen protein predicted to cause a reaction in a defined small proportion of the allergic population. The VITAL programme publishes reference doses derived from clinical challenge data, expressed as milligrams of total protein from the allergenic food, most commonly at the ED05, the dose predicted to elicit a reaction in 5% of allergic individuals.
Three points are routinely misread:
- The dose is expressed as protein from the allergenic source, not as the weight of the ingredient. One gram of milk powder is not one gram of milk protein.
- It is a population value, not a safety guarantee for any individual. It gives you a defensible basis for a decision; it does not make a residue harmless.
- The published values are revised as new clinical data emerges. Cite the version you used and diarise a review, or your file will quietly age out of date.
The calculation
Turning a reference dose into something you can compare a swab result against takes one line of arithmetic:
| Step | Value |
|---|---|
| Reference dose (mg of allergen protein) | RD |
| Serving size of the finished product (g) | S |
| Action level (mg allergen protein per kg of food) | RD ÷ S × 1000 |
Worked example. A reference dose of 0.2 mg of milk protein, in a product with a 30 g serving, gives 0.2 ÷ 30 × 1000 = 6.7 mg of milk protein per kg. Measured cross-contact below that level does not require a precautionary statement. Above it, it does, or you change the process until it is below.
| Serving size | Action level (mg protein per kg) | What it means in practice |
|---|---|---|
| 10 g (a sachet, a portion of seasoning) | 20.0 | Relatively forgiving. A small serving dilutes the dose the consumer receives |
| 30 g (a biscuit portion, a snack bag) | 6.7 | Typical confectionery and bakery territory |
| 100 g (a ready meal component) | 2.0 | Tighter. Requires genuinely validated cleaning |
| 250 g (a full ready meal) | 0.8 | Demanding. Often drives dedicated equipment or reformulation |
The serving size is doing a lot of work in that equation. A 30 g serving and a 250 g serving of the same food give action levels that differ by a factor of eight. This is why an action level belongs to a product, not to a factory, and why a single site-wide “limit” pinned to a noticeboard is a sign the calculation was never done.
Where the residual number actually comes from
An action level is only half the decision. The other half is a measured figure for what is actually carried over, and that comes from a cleaning validation study rather than from routine swabbing.
- Choose the worst case. The highest-allergen product, the hardest-to-clean equipment, the shortest realistic changeover, the least experienced shift. Validating your easiest scenario proves nothing.
- Identify the hardest-to-clean locations. Dead legs, gaskets, seals, valve seats, the underside of paddles, corners of hoppers, the point where a belt enters a former. These drive the result.
- Run the clean exactly as written. If the validated procedure is not the one operators actually follow, the study measures fiction.
- Sample properly. Swabs from defined locations of defined area, rinse-water samples where the system is enclosed, and a first-product-through sample, which is usually the number that matters most.
- Quantify. Lateral flow devices give a rapid pass or fail; quantitative ELISA gives the milligrams per kilogram you need to compare against the action level. Record the method, the kit, the detection limit and the analysing laboratory.
- Repeat. Three consecutive successful runs is the usual expectation before a cleaning procedure is treated as validated, with routine verification thereafter.
Interpret the result against the action level, not against the detection limit of the kit. “Not detected” is a statement about the method’s sensitivity, not about the product’s safety, and the two are only the same thing when the detection limit sits below your action level. If it does not, the test cannot answer your question.
When the number says the statement is needed
A result above the action level is not automatically a “may contain” label. It is a decision point with four options, in order of preference:
- Change the sequence. Run the allergen-free product first after a full clean, and the allergen-containing product last before one. Often removes the problem at no capital cost.
- Improve the clean. Extend, reconfigure or dismantle further. Re-validate afterwards; an improved clean that has not been re-validated is an assertion.
- Dedicate the equipment. Sometimes a single dedicated part, a hopper, a set of belts, a filler head, is enough.
- Reformulate or accept the statement. If the residual risk genuinely cannot be engineered below the action level, a precautionary statement is the honest outcome, and now it is defensible.
What the standards expect
BRCGS Food Safety Issue 9 treats allergen management as a fundamental requirement at clause 5.3. A fundamental is not a clause you argue about at the closing meeting: a significant failure against it puts certification itself at risk. The expectation is a documented risk assessment, validated controls, and precautionary labelling used only where the assessment supports it.
FSSC 22000 Version 7, published in May 2026, similarly expects allergen cross-contact risk to be assessed and controlled rather than labelled around. In both schemes the auditor’s question is the same, and it is rarely “do you have a may contain statement?” It is “show me the number behind this one.”
What the file should contain
| Document | What it must show |
|---|---|
| Allergen risk assessment | Which allergens are on site, which lines they touch, and where cross-contact is credible |
| Action level calculation | Reference dose used and its version, serving size, and the resulting mg/kg |
| Cleaning validation report | Worst case, sampling plan, method, results from three runs, conclusion |
| Routine verification records | Ongoing swabs or rapid tests against the validated procedure |
| Decision record | The conclusion, the wording chosen, the named approver and the date |
| Review trigger list | What changes force a re-assessment: new product on the line, recipe change, equipment change, supplier change |
Wording and placement
- One phrase, used consistently across every product and every pack. A portfolio carrying four different precautionary phrasings signals that nobody owns the decision.
- Next to the ingredient list, not on a back seam, not in a different type size, not on the base of a tub.
- Specific to the allergen you have assessed. “May contain traces of nuts” where the risk is milk is worse than useless.
- Avoid the word “traces” where you can. It implies a quantity you have not measured, and it means nothing to a consumer deciding whether to eat.
- Reviewed when the line changes. A new product on a shared line changes the arithmetic for everything else on it.
Frequently asked questions
Is “may contain” required by South African law?
No. Precautionary labelling is voluntary. What is not voluntary is the ingredient declaration itself, and an allergen present as an ingredient must be declared whatever precautionary wording appears on the pack.
Can we put “may contain” on everything to be safe?
It is legally risky and commercially costly. Blanket precautionary labelling removes product choice from allergic consumers, is treated by auditors as evidence of an unvalidated process, and in several markets attracts regulatory attention in its own right.
What is an action level?
The concentration of allergen protein in the finished food, in mg per kg, at which a precautionary statement becomes necessary. It is calculated from the reference dose and the serving size: reference dose divided by serving size in grams, multiplied by 1000.
Do we need analytical testing to support the decision?
You need evidence of the residual level. That usually means a validated cleaning study with quantitative analysis, most commonly ELISA, supported by swab and rinse results. A visual inspection alone will not support an action-level decision.
Is a “not detected” result the same as being below the action level?
Only if the method’s detection limit is below your action level. Otherwise “not detected” describes the limits of the test rather than the safety of the product. Record the detection limit alongside every result.
How many validation runs are enough?
Three consecutive successful runs under worst-case conditions is the usual expectation, followed by routine verification. Repeat the validation whenever the product mix, equipment or cleaning procedure changes.
Who signs off a precautionary statement?
A named person with the risk assessment, the cleaning validation data and the supplier specifications in front of them. The signature and the date are part of the evidence.
Which ASC course covers this
Allergen Labelling and Artwork Control works through the decision and the arithmetic in detail: when a precautionary statement is justified, how to calculate an action level for your own product, the wording and placement rules, and how to keep the decision consistent across a portfolio.
For the analytical and validation side, Allergen Management in the Food Supply Chain covers the site programme, and the advanced pathway goes further: Advanced Part 1: Risk Assessment and Cleaning Validation covers quantitative risk assessment and cleaning validation in depth, and Advanced Part 2: Removal Science, Compliance and Crisis Management covers removal science, analytical methods and the regulatory response.