To the main pagePrevious ArticleNext Article

Food Safety Focus (1st Issue, August 2006) – Food Safety Platform

Hazard and Risk in Food Safety (Part I)

Reported by Anna TANG, Research Officer, Risk Assessment Section and
Mary WONG, Research Officer, Risk Communication Section, Centre for Food Safety

Risk is part of everyone's life. For example, there is a risk of injury due to traffic accidents when we go out onto the street. Also, when we put money in a bank, there is a risk of not being able to retrieve it if the bank goes bankrupt.

Hazard ≠ Risk

This article introduces the concepts of hazard and risk, within the framework of food safety control. Identification of hazards and estimation of the risk concerned are central components in ensuring food safety and safeguarding public health.

"Hazard" and "risk" are terms commonly used in scenarios where possible adverse outcomes are expected. Though these two terms are related to each other, they are distinct entities with different meanings.

Hazard is a factor or agent which may lead to undesirable effects, whereas, risk refers to the probability that the effect will occur. The table below compares the estimated risk of certain events that we may encounter within the population.

Risk in Qualitative Source Annual Risk
Injury due to traffic accident 1 in 460
Death due to heart disease 1 in 1 170
Liver cancer from all causes 1 in 4 130
Death due to traffic accident 1 in 43 300
Death due to lightening strike 1 in 2 000 000
Death due to plane crash (airliner) 1 in 52 600 000

In the context of food safety, a "hazard" can be classified as a substance or agent present in food that has the ability or the potential to cause an adverse health effect to the consumer. The substance can be a biological, chemical or physical agent. For example, salmonella, a biological agent, may be present in raw eggs. Ingestion of salmonella may result in food poisoning. Therefore, salmonella in food is considered a biological hazard and may also pose a potential risk to the consumer. Mercury, a natural contaminant that may be present in some foods, is regarded as a chemical hazard and could also pose a potential risk to the consumer.

In determining whether there is a "risk" posed to humans from exposure to a specific hazard through food, there must be a consideration of the likelihood of consumption and the nature or severity of the adverse health effect posed by a certain hazard if consumed. While "risk" already implies the existence of a hazard, it has the additional component of the "chance" or "probability" of that happening to the individual or the population as a whole, as well as taking into account the severity and impact of the health effect that may occur as a result of being exposed to the hazard. For example, although salmonella may be present in raw eggs, the risk of getting salmonella food poisoning is minimal when the egg is thoroughly cooked before consumption to eliminate the hazard and thus minimizing the chance of exposure. However, if the eggs are eaten raw, the health risk from salmonella in eggs will be higher as a result of the higher likelihood that the hazard will be present and consumed. Similarly, mercury may be present in food and could pose a potential risk to the consumer. However, as in the cases of most chemical hazards, if the amount of mercury in the food is low, the risk to the consumer will also be low as occasional exposure to low levels of mercury will usually not cause adverse health effects in humans. Also in food safety assessment with respect to chronic toxicity, exposure and health effects of a chemical usually refer to the intake of that chemical over a lifetime. Transient excursion above the safety reference value would have no health consequences provided that the average intake over long period is not exceeded.

Aflatoxin as an Example

Aflatoxin is a food hazard and the concern is on its ability to cause liver cancer when people are exposed to high levels over an extended time. Its level in food is therefore regulated by law to prevent excess exposure. The following hypothetical scenario shows the estimated risk of occurrence of liver cancer due to aflatoxin intake.

According to the average pattern of peanut consumption in Hong Kong and assuming that peanuts contain aflatoxin at a level two times the legal limit, a healthy person who eats peanuts every day of their life would have a risk of cancer due to aflatoxin intake of 1 in 2 300 000 per year. This level of risk is very low and is comparable to the risk of death due to lightening strike.

In general, an exceedance of the level of a food hazard over the regulatory standard does not necessarily cause harm to health. The individual impact should depend on the risk assessment result.