Research and analysis

Pilot study to evaluate the value of occupational health data to improve the quality of the estimate of health effects from radiation exposure in the NRRW

Updated 22 August 2024

Summary

We plan to undertake a pilot study of electronically stored occupational health records from Springfields Fuels Ltd to see if they contain useful information about individuals:

• smoking rates
• alcohol consumption
• hypertension
• diabetes
• exposure to industrial hazards such as asbestos

We want to know if we can use this information to better estimate workers’ baseline risk of common diseases such as cancer and heart disease that are affected by these factors.

With better baseline disease estimates we hope to improve the accuracy of our estimates of potential radiation risks of these diseases.

Background

The aim of the NRRW is to provide evidence about the health effects of occupational radiation exposure by undertaking surveillance of radiation workers employed in the UK since the 1950’s. The study population is now around 300,000 workers and still growing.

A person’s baseline risk of many common diseases such as cancers, heart disease and strokes is highly influenced by health and lifestyle factors such as smoking, alcohol consumption, obesity, hypertension, diabetes and industrial hazards such as asbestos.

Currently NRRW holds no information about these factors. This means our analyses of the risks of these common diseases from radiation exposure cannot take into account the potentially large individual variability in the underlying risks of these common diseases according to these factors.

For example, we cannot allow for differences in lung cancer risk between smokers and non-smokers before investigating the risk of lung cancer from radiation exposure.

We would like to obtain information about these health and lifestyle factors for NRRW participants so we take the variation of diseases with these factors into account as we believe it would help provide more accurate estimates of the radiation risks for these diseases.

Radiation workers all undergo occupational health screening before employment and at regular intervals, usually yearly, during their working life and the records are retained long term by the employers.

Discussions with many of the employers that participate in the NRRW have identified that these employers have a mixture of paper occupational health records and more recent electronic records that might contain information about the lifestyle and health factors we are interested in.

An initial feasibility study of a small sample of both paper and anonymised electronic occupational health records of workers at the Sellafield site (formerly part of British Nuclear Fuels Ltd and now managed by the Nuclear Decommissioning Authority) revealed that information about the factors of interest were potentially available in these records. However, the feasibility study was not able to determine if the actual data recorded in the records more widely was sufficiently complete and informative to be useful since it only looked at what categories of information were available and not the actual data values.

For example, for the smoking data, it would be very helpful to know:

• what were the proportions of smokers and non-smokers?
• for how many people did the data change over time?
• for the blood pressure data, what proportion of workers ever had a measurement recorded outside the normal range? 

Details of the pilot study

As the feasibility study did not provide sufficient justification to seek to collect occupational health data more widely for the NRRW participants we propose an additional pilot study. Extracting information about the health and lifestyle factors from paper records could be expensive and time consuming and while collecting it from electronic records is easier, we want to have some reassurance that the data are sufficiently complete to be useful.

As we can access the data from electronic records quickly and cheaply, we plan to undertake a pilot study based on the Springfields Fuels Ltd occupational health records electronic archive. We believe there are around 7,000 archived records that could potentially be used for this pilot study with up to 36 years of follow-up.

The pilot study will extract identifying information and information on smoking, alcohol consumption, blood pressure, obesity, and exposure to potentially harmful industrial chemicals and asbestos from the electronic archived occupational health records.

These will then be matched to the workers’ records on the NRRW. 

An anonymised dataset comprising the workers’ lifestyle and health information, their employment information and their follow-up data will be created.

This dataset will be used to address the following questions:

• how does the quality and quantity of information on the factors vary?  For example, what proportion of workers smoked?
• do workers’ smoking status vary over time?
• how many workers have blood pressure or obesity measurements outside the normal range either at the start of employment or at any subsequent time covered by the records?
• how do records of alcohol consumption change over time? 
• how complete is the information on asbestos exposure?
• is there any evidence that diseases rates among the workers varies with any of the lifestyle or health factors? (for example, are the rates of lung cancer and circulatory diseases among NRRW participants different among smokers and non-smokers?)
• is it possible to see any differences for the questions above between radiation workers and non-radiation workers? (for example, is the data more complete or information for one group?)
• do disease rates differ, for a given heath or lifestyle factor, between radiation and non-radiation workers?

Once the study has been completed the dataset will be deleted but the programs used to extract the health and lifestyle factors and to do the matching to the NRRW records will be retained so the process could be repeated with little effort.

We will seek to publish the results of the pilot study in the peer reviewed academic press (only aggregated data would be published).

Potential results and their implications

Reviewing the values of the health and lifestyle factors will provide evidence about how likely they are to have a positive impact on the NRRW radiation risk estimates in the long term. The follow-up data may provide some early indications of variability of disease rates across the health and lifestyle factors, but it is unlikely that the number of deaths and cancer incidences among these 7,000 workers will be sufficient for more detailed analyses at this time.

There are a range of possible outcomes to using health and lifestyle factors in future analyses of the NRRW.  At one extreme, the data might provide evidence that elevated risks of diseases caused by occupational radiation exposure are independent of the health and lifestyle factors.  At the other extreme, it might provide evidence of the opposite. For example, that smokers and non-smokers have different excess risk of smoking related diseases per unit of occupational radiation exposure.  It is also entirely possible that different outcomes are observed across a range of diseases where we observe excess risk from occupational radiation exposure.

Evidence for any of the outcomes would be of great interest to the national and international bodies that set the standards for radiation protection as there are very few other sources of such information.

If this pilot project is successful, then we will seek to enter discussions with stakeholders to progress to the collection of health and lifestyle factors, from both the electronic records and if possible, any available paper records, and adding it to individuals NRRW records for long term retention and use in future analyses.

If collection of these data proves successful for Springfields workers, then we aim to approach other employers with a view to collecting similar data about their employees.

If you would like more information about this work, or if you would like to know if your data will be included in the study and you would like to opt out, please contact the study team at radiationworkerepidemiology@ukhsa.gov.uk