FOOD SAFETY AND QUALITY ASSURANCE: RISK ASSESSMENT BASICS
Diagram
Hazard
Something in food that can cause harm
↓
Exposure
How much of it reaches the person, and how often
↓
Risk
Chance of harm, and how serious the harm would be
Figure 1: A hazard plus exposure gives risk. The hazard alone does not tell you the risk.
Introduction
Hazard and risk are two words that are often swapped, but they mean different things, and the difference decides what a food worker must do. A hazard is anything in food, or in the way food is handled, that can cause harm to health. Risk is the chance that the harm will actually happen, and how serious it will be if it does. A sharp bone in fish is a hazard. The risk is higher for a small child who eats quickly than for an adult who eats slowly and picks the bones out. In short, hazard is the thing that can hurt, and risk is the chance and the size of the hurt.
Table 1: Quick comparison of hazard and risk
| Aspect | Hazard | Risk |
|---|---|---|
| Definition | Anything in food, or in handling, that can cause harm to health | The chance that harm will happen, and how serious it will be |
| Kinds | Biological, chemical, and physical | Likelihood times severity: two parts that must both be weighed |
| Example | A piece of glass in a jar of pickles | The chance someone swallows the glass and is cut, which depends on whether it is noticed and removed first |
| Measured by | Naming the thing: germ, toxin, metal fragment, allergen | A score: likelihood 1 to 5 times severity 1 to 5 |
| Can it be zero? | A hazard can be removed, such as by cooking or by a metal detector | Risk can be made low, but it is rarely zero while food is eaten |
| Changes with | The food and the process | The eater, the amount eaten, and how often |
| Used in | Hazard analysis, the first HACCP principle | Risk assessment, risk management, and risk communication |
| Key point | A hazard is the thing that can cause harm | Risk has two parts: how likely is the harm, and how bad would it be? |
Scientific explanation
Definition
A hazard is anything in food, or in the way food is handled, that can cause harm to health. Hazards fall into three large groups: biological hazards, such as bacteria, viruses, moulds, yeasts, and parasites; chemical hazards, such as natural toxins, pesticide residues, cleaning chemicals, and heavy metals such as lead; and physical hazards, such as stones, glass, metal fragments, and bone pieces. Risk is the chance that the harm will actually happen, and how serious it will be if it does. Risk has two parts, and both must be weighed: how likely is the harm, and how bad would it be?
Working principle
Hazard work is hazard analysis: for each step of the process, name the hazards that could occur, and judge which ones are important enough to control. Risk work has three parts, in order: risk assessment, which asks what the hazard is, how much exposure there is, and what dose causes harm; risk management, which decides what to do, such as setting a limit, banning a substance, ordering a recall, changing a process, or requiring a label; and risk communication, which tells the people affected what the risk is, what is being done, and what they can do themselves, plainly and early.
Apparatus
Hazard work uses laboratory tests to find germs, toxins, and residues, and detection tools such as metal detectors to find foreign objects. Risk work uses the numbers those tests give, plus intake surveys and body weight data.
Measurement procedure
Risk is scored by rating likelihood from 1 to 5 and severity from 1 to 5, then multiplying the two numbers. The bands used in the FTN notes are: low, score 1 to 4; medium, score 5 to 9, meaning control and check; high, score 10 to 16, meaning act now; very high, score 17 to 25, meaning stop until fixed. A hazard scores likelihood 2 and severity 5 when it is rare but deadly, which gives 10, in the high band.
Factors affecting readings
The score changes with the evidence. A rare but deadly hazard can outrank a common but mild one when the numbers say so, and the numbers keep the team honest: a hazard cannot jump the queue because one person fears it most. Exposure also changes the risk: the same amount is a larger dose for a small child than for a large adult, so exposure is divided by body weight.
Formulas and calculations
Risk score: risk score = likelihood (1 to 5) x severity (1 to 5). Worked example from the FTN notes: a germ that causes mild diarrhoea in many people may score 4 x 2 = 8, in the medium band, while a toxin that kills rarely may score 1 x 5 = 5, also medium, so the common mild hazard ranks higher. A toxin that is both likely and deadly scores 5 x 5 = 25, in the very high band, and jumps to the top at once.
Exposure: daily intake = concentration in the food x amount eaten per day, then divide by body weight. Worked example from the FTN notes: a spice carries lead at 0.5 mg in each kilogram. A person eats 5 g of that spice a day, which is 0.005 kg. Step 1: daily intake is 0.5 x 0.005 = 0.0025 mg of lead a day. Step 2: for a 60 kg adult, divide 0.0025 by 60, which gives 0.000042 mg for each kilogram of body weight per day. Step 3: compare that number with the safe level set by experts, called a tolerable intake. If the exposure is well below it, the risk is low; if it is near or above it, the food needs control.
Industrial applications
- Hazard analysis: the first step of every HACCP plan and every HARPC food safety plan.
- Risk scoring: ranking hazards so the team controls the worst first, instead of the one feared most.
- Risk management: setting legal limits, ordering recalls, changing a process, and writing labels.
- Risk communication: telling buyers and the public what the risk is and what to do, plainly and early.
Advantages and limitations
Hazard thinking advantages: simple and direct: name the thing that can hurt and remove it or control it. Limitations: naming hazards alone does not say which one matters most.
Risk thinking advantages: ranks hazards by likelihood and severity, so effort goes where it protects most people. Limitations: scores need honest evidence, and a score can mislead when the evidence is thin, so scores must be reviewed when new facts arrive.
FAQ
Is a small number of bacteria in fresh milk a hazard?
Yes, it is a hazard, but the risk is low while the milk is fresh and cold. The same milk left warm for six hours carries far more risk, because the germs have grown.
A jar of pickles holds a small piece of glass. Is the glass a hazard or a risk?
The glass is a hazard. The risk is the chance that someone swallows it and is cut, which depends on whether the glass is noticed and removed before eating.
Why is exposure divided by body weight?
Because the same amount is a larger dose for a small child than for a large adult.
What is the difference between risk assessment and risk management?
Assessment is the science: what is the hazard, how much exposure, what dose causes harm. Management is the decision: set a limit, ban a substance, order a recall, or change a process.
References and further reading
- FTN subject Food Safety and Security, Unit 1: What Food Safety Means, Hazards and Risk, including the risk score bands and the lead exposure worked example.
- Book on disk: Food Quality Assurance: Principles and Practices.
- Government source (regulatory fact): the risk assessment, management, and communication steps follow the Codex Alimentarius approach used in the FTN notes.
