Table 3: Examples of key considerations in assessing the radiological implications of contaminated land in existing exposure situations

1 January 2000

Question Relevance
How confident am I in the estimate of dose and in the probability of receiving that dose? This is particularly important if the estimated dose is approaching or exceeds a dose criterion. Improved estimates may be needed and this may require a review of the model used or obtaining more site specific data by monitoring, surveying or experiment.
Where contamination is by discrete radioactive objects, could exposure give rise to serious deterministic effects? Some deterministic effects are transient in nature and are therefore not considered to be serious deterministic effects. If serious deterministic effects could be received then the probability of receiving that dose should be reduced to be negligible. Where the probability of receiving a serious deterministic effect is negligible then the remediation strategy need only consider simple actions. More extensive or disruptive actions should be considered if the probability is higher than this.
Where contamination is by discrete radioactive objects, are experimental studies needed to characterise the objects? Using standard models may not give a reasonable representation of the situation and so experimental work, for example in vivo or in vitro work to define uptake factors, should be considered. This is important if the estimated doses are approaching a dose criterion.
Would additional monitoring be useful? Additional information on the distribution of the contamination and its characteristics would improve confidence in the dose and probability estimates. Monitoring over extended periods would improve understanding of the level of contamination in dynamic environments, such as beaches. Trigger levels could be specified to indicate when additional work is required. More sensitive equipment may become available and its use would improve knowledge on the contamination and its distribution. Reassurance monitoring may be requested by stakeholders.
What is the source of the contamination? Will recontamination occur? What is the site history? Knowledge of the source of the contamination and how the level of contamination could change over time is very important. Such knowledge will assist in understanding the extent of the contamination and whether additional monitoring is required. This is particularly important if new contamination could be added to the site or if the site is part a dynamic environment. If a suitable site history is not available then there may be a need to rely more on monitoring.
What are local stakeholder views? Pressures from stakeholders, including regulators and local residents, may impact on any remediation strategy developed.
What is the appropriate regulatory regime? Identifying the relevant regulatory regime allows estimates of dose or risk to be placed within a suitable context and may provide direction on future action, for example, classifying land as contaminated or removal of a site license.
Is remediation justified and optimised? Appropriate options will vary from site to site, depending on site-specific characteristics. Justification and optimisation of the remediation strategy should be based on the best available technique for that site, taking into account potential exposure to human and non-human species, societal and economic factors. The ‘no remediation’ option should be considered as part of the protection strategy if residual doses are below the reference level set.

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