# Risk

Risk relates to the probability or chance that an outcome (e.g. lung cancer) will occur during a given length of time. Terms relating to risk are listed below:

Absolute risk: the probability that a particular adverse event (e.g. the incidence of a particular disease or death) will occur in a specific period.

Lag: for diseases such as cancer, there is a minimum latent period (latency) between an exposure and the clinical manifestation of a consequent excess risk of the disease during which no cases attributable to the exposure occur. Therefore, a lag is often introduced in an assessment such that no cases occurring within the minimum latent period following an exposure are included in the assessment. Further, if an exposure is protracted, such as occupational exposures to radiation, exposures are usually lagged so that doses received during the minimum latent period immediately preceding the time at which an assessment is conducted are excluded from the assessment. Examples of minimum latent periods are 2 years for leukaemia, and 5 or 10 years for lung cancer.

Lifetime risk: the risk over the lifetime of a particular individual of mortality or morbidity from a particular adverse event (e.g. lung cancer) that is related to a given factor (e.g. an exposure to radiation). The lifetime risk is expressed in terms of the length of life expected for a particular individual, such as the risk over the remaining lifetime of a specific disease following a particular dose of radiation at a given age at exposure, assuming an overall lifespan of 90 years.

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## Previous glossary entries

## ICRP Glossary 2021

A multi-attribute quantity expressing hazard, danger or chance of harmful or injurious consequences associated with actual or potential exposures. It relates to quantities such as the probability that specific deleterious consequences may arise and the magnitude and character of such consequences.

### from ICRP Publication 132, 2016

Risk relates to the probability that an outcome (e.g. cancer) will occur. Terms relating to risk are grouped together here: Excess relative risk is the rate of disease in an exposed population divided by the rate of the disease in an unexposed population minus 1. This is often expressed as the excess relative risk per Sv. Relative risk is the rate of disease in an exposed population divided by the rate of the disease in an unexposed population.

### from ICRP Publication 126, 2014

Risk relates to the probability that an outcome (e.g. lung cancer) will occur. Terms relating to risk are grouped together here.

### from ICRP Publication 122, 2013

The probability of harmful or injurious consequences (e.g. cancer) associated with exposures or potential exposures in a year. It takes into account the probability of receiving a dose in a year, and the probability that the dose received will give rise to harm. Risk = likelihood of occurrence · seriousness if incident occurs.

### from ICRP Publication 115, 2010

Risk relates to the probability or chance that an outcome (e.g. lung cancer) will occur.