Cancer Incidence and Mortality Experience of a British and an International Cohort of Workers Occupationally Exposed to Styrene

The Institute for Occupational Medicine (IOM) and the Health and Safety Executive (HSE) require NHS England data for the purpose of the following research project: "Cancer Incidence and Mortality Experience of a British and an International Cohort of Workers Occupationally Exposed to Styrene".

Styrene is a high-production high-volume chemical with about 18 thousand tonnes produced annually in the manufacture of plastic and synthetic rubber products worldwide. The general population is exposed to very low levels of styrene while occupationally exposed workers may encounter much higher levels of exposure. Around 40 years ago, findings among workers in the synthetic rubber industry suggested an increased risk of leukaemia and lymphoma. However, interpretation of this finding was hampered by co-exposure to other chemicals. Within the reinforced plastics industry, co-exposures to other known and suspected carcinogens are limited. This industry is therefore ideal for studying the potential carcinogenicity of styrene.

The research is proposed as a consequence of the International Agency for Research on Cancer changing its classification in 2019 for the carcinogenicity of styrene from “possibly carcinogenic” to “probably carcinogenic”. The main shortcoming in the evidence preventing a conclusion of definite carcinogenicity was the lack of robust evidence from human epidemiological studies from the type of study which is the subject of this agreement.

This data sharing agreement is for a UK-based study, and concerns the collection of data on ~1800 UK study participants who have worked in the glass-reinforced plastics manufacturing industry.

The aims of the UK-based study are:

1) to understand which participants have died or contracted cancer, what the cause of death and/or type of cancer was and when these events occurred

2) to understand whether cancer is occurring in this study population at a rate that is consistent with expectations after adjusting for age, sex and calendar year

3) to compare cancer rates, after the same adjustments, among those with higher and those with lower (or zero) exposure to styrene. This is expected to allow society to understand whether occupational exposure to styrene increases a person’s risk of contracting cancer.

This data sharing agreement covers a request for Demographics, Cancer Registration and Civil Registration (Deaths) data from NHS England for the ~1800 UK workers from the glass-reinforced plastics industry in order to meet the above aims. The study hopes to achieve its aims by comparing cancer rates in the study population with the general population and by comparing cancer rates in workers exposed to higher levels of styrene with those exposed to lower (or zero) levels of styrene.

Although the study is primarily interested in lymphatic and haematopoietic cancers (cancers of the immune system), other cancers have been implicated. It is also important to look at mortality from other causes as this provides additional important evidence, e.g. whether there exists a “healthy worker effect” in the cohort (an effect that is well-known in epidemiology that workers exhibit a healthier mortality profile than the general population because of selection effects associated with employment.) In practice, even though lymphatic and haematopoietic cancers are those of primary interest, the study intends to look at a range of other causes to see if any of them are in excess and whether any excess found might be related to styrene exposure. This is standard practice for epidemiological studies of this type.

The Institute of Occupational Medicine (IOM) wishes to obtain mortality, cancer registration and demographic data for this group of workers from across England and Wales for all available data years. IOM requests that identifiable data are returned to ensure that there are no transcription errors and that the correct events are allocated to the current individual. Once the matching has been completed, IOM will destroy the identifiers that have been received from NHS England. IOM needs to have deaths, cancer registrations and reason for removal from the NHS for as many years as possible, and for all of the workers in the cohort from across England and Wales, to ensure the study has maximum statistical power. This is the only way to carry out such occupational cohort studies. There are no alternative, less intrusive ways of achieving the purpose. IOM will remove day of death and day of birth from the analysis data sets to further minimise the probability of study participants being identified by those carrying out the statistical analysis of the study data. Only those data fields necessary to meet the objectives of the study have been requested.

The data controllers for the UK study are the Institute of Occupational Medicine (IOM) and the Health and Safety Executive (HSE). The IOM will also be processing the data.

The IOM is a registered charity whose mission is to understand occupational, environmental and public health risks in order to make our world a healthier and more sustainable place to live. The data processing described here is to support scientific and statistical research. Specifically, data is processed under the following articles of the Data Protection Act 2018:

Article 6 (1) (f) Legitimate interests: the processing is necessary for your legitimate interests or the legitimate interests of a third party unless there is a good reason to protect the individuals personal data which overrides those legitimate interests.

The data is required for a research project - and therefore IOM process the special category data (health data) under the following article of GDPR - Article 9 (2) (j): processing is necessary for archiving purposes in the public interest, scientific or historical research purposes or statistical purposes in accordance with Article 89(1) based on Union or Member State law which shall be proportionate to the aim pursued, respect the essence of the right to data protection and provide for suitable and specific measures to safeguard the fundamental rights and the interests of the data subject.

Processing personal data is necessary for IOM's legitimate interests. The data to which access is requested are proportionate and necessary to achieve those interests. IOM has completed a legitimate interests assessment (LIA) and is satisfied that the interests of the data subjects do not override IOM’s legitimate interests; that they would reasonably expect the processing and it would not cause unjustified harm. The IOM have worked closely with the industry (via the HSE and the Trades Union Congress) to notify glass-reinforced plastic workers of the existence of the study. A worker leaflet was produced to notify individuals of the opportunity to opt out of the study. National data opt-outs will also be applied.

The Trades Union Congress are of the view that it is acceptable for the study to proceed without prior consent from the people whose confidential patient information is being used. The Trades Union Congress consider that the study is significant and will improve knowledge of the possible cancer risk from occupational exposure to styrene.

This research study is funded by the HSE, and the data from this study were originally assembled by the HSE in the late 1980s/early 1990s. The data, which consists of information about the identity and work situation of approximately 1800 workers employed in the glass-reinforced plastics manufacturing industry between ~1961-1988, was assembled in order to assess whether occupational exposure to styrene was associated with an increased risk of cancer. The proposed further assessment of the long-term mortality and cancer experience of these workers essentially amounts to an update of the original study in line with the original purpose, albeit carried out by IOM and facilitated by HSE via sharing of the original study dataset. Although HSE will not be in receipt of any new information about cancer registrations and deaths, or any demographic information, HSE will retain ownership of the original data, and be responsible for facilitating any future updates. As such, it is appropriate for HSE to be regarded as a data controller for the purposes of the exercise to update the cancer and mortality experience of these workers.

The HSE’s UK GDPR legal bases are Article 6(1)(e) - processing is necessary for the performance of a task carried out in the public interest or in the exercise of official authority vested in the controller given HSE’s statutory responsibility under the Health and Safety at Work Act to carry out appropriate research in order to fulfil its duty to protect the health and safety of British workers, and Article 9(2)(j) - processing is necessary for archiving purposes in the public interest, scientific or historical research purposes or statistical purposes, as the purpose of this scientific research is to help determine the long term health implications of around 1800 glass-reinforced plastics manufacturing industry workers who were exposed to styrene, ultimately to inform future health and safety policy and procedures that are designed to protect future generations of workers in this sector.

The purpose of processing the data is for reasons of public health and research to further understand whether styrene is a carcinogen. The data will be stored securely, not published in a way that identifies anyone, only used for the purposes for which it is collected, and kept only as long as is necessary to undertake the research.

Past workers in the industry could bring medico-legal cases against employers if styrene is found to be a carcinogen; and/or the cancer type involved with the associated exposure circumstances may get added to the list of prescribed diseases, maintained by the Industrial Injuries Advisory Council.

The data from this study were originally assembled by the Health and Safety Executive (HSE) in the late 1980s/early 1990s and consists of work histories and some demographic data for ~1,800 workers in the glass reinforced plastics manufacturing industry. The HSE will provide this cohort data to the Institute for Occupational Medicine (IOM) under a separate Agreement between HSE and IOM.

The Institute for Occupational Medicine (IOM) will send the name(s), sex, date of birth and postcode of the ~1,800 workers to NHS England for the purpose of understanding any deaths, cancer registrations or exits from the NHS (as listed in the demographics dataset) experienced by the cohort. Once the linkages have been carried out by NHS England, the resulting mortality, cancer and demographics data will be sent to IOM (all uploads and downloads to and from NHS England will be made by authorised IOM staff using the NHS England secure electronic file transfer service). IOM requests that participant names, sex and date of birth are returned alongside the unique study ID to ensure that there are no transcription errors and that the correct events are allocated to the correct individuals.

Data from NHS England will be linked to each worker’s occupational data from the Health and Safety Executive (HSE). The results of the matching will be checked and a pseudonymised data set created that will be used for analysis within IOM. No names will be contained in the analysis data set, nor any other identifiers such as postcode. Dates of birth, dates of cancer registrations and dates of death will only be stored as month and year. All identifiable information will be stored separately to the pseudonymised analysis dataset, and identifiers provided by NHS England will be destroyed once the matching is complete.

IOM Data is held on secure cloud-based storage on Microsoft Sharepoint / Onedrive for business. Study folders containing confidential data, are specifically highlighted in our SharePoint Structure. access to these folders can only be granted to by IT personnel, all sharing from highly confidential folders is restricted. All IOM Laptops are fully encrypted, and all logins to OneDrive are protected by MFA (Multi Factor Authentication) and file actions to OneDrive are monitored / logged.

Microsoft Supply IT infrastructure for IOM and are therefore listed as data processors. Whilst Microsoft provide the underlying infrastructure, the data itself is not accessible by Microsoft.

IOM will employ standard epidemiological techniques to analyse the data in order to understand whether exposure to styrene is associated with an increased risk of cancer. Two main types of analyses are contemplated, one that compares the cancer rates in the study population with the general population of England and Wales, and another in which cancer rates in workers with assessed higher exposure to styrene are compared to workers with assessed lower/zero exposure.

All NHS England data will be destroyed when this Data Sharing Agreement expires, and the data that originated from HSE will be returned to HSE.

Outputs are expected to include:

• Submissions to peer-reviewed journals

• Worker leaflet in lay language for the industry

• IOM website updates

• Twitter/LinkedIn posts

• Conference presentations/posters

• Short report for funder

No identifiable data will be included in any outputs from this project. All outputs will be aggregated with small numbers suppressed.

The results of the UK study are anticipated to be presented at appropriate scientific conferences such as EPICOH Scientific Committee on Epidemiology in Occupational Health 2023 and the UK/Ireland 1-day meeting on Occupational and Environmental Epidemiology in 2023.

IOM anticipate that the study results will be published in the journal Occupational and Environmental Medicine.

In addition, IOM are expecting to present the results of the study to the industry and its workforce. HSE would distribute a leaflet prepared by IOM in lay language explaining the results of the study, highlighting any implications for policy, practice and future research. IOM also plan to send the leaflet to the Trades Union Congress (TUC) for onward distribution to the relevant workers (i.e. those occupationally exposed to styrene).

The findings are intended to be made available on the IOM website as a blog post and possibly in other dissemination materials such as infographics. It may also be disseminated via IOM’s research newsletter. The findings are also planned to be made available via Twitter and LinkedIn. The exact nature and extent of this would depend on the findings of the research.

It is hoped that the UK study will be published in 2023. The conference presentations and other dissemination materials would be made available as soon as possible once the results have been published.

Estimates of how many people in the UK are occupationally exposed to styrene are not available, however styrene is one of the top 50 chemicals manufactured in the world. Occupationally, exposure occurs in styrene production, production of polystyrene and other styrene-containing polymer resins, plastics and rubber products fabrication, fabrication of reinforced-polyester plastics composites and use of products containing styrene such as floor waxes and polishes, paints, adhesives, putty, metal cleaners, autobody fillers and varnishes. Globally, it is estimated that more than 15,000 industrial plants in many countries produce or use styrene in the manufacturing of polymeric products.

The impact on occupational health of this research depends on the findings. There are three possibilities:

(i) No association is found between occupational exposure to styrene and increased risk of cancer;

(ii) No association is found, but there is a suggestion that further work is required to clarify matters; or

(iii) There is an association found.

The findings in (i) will provide reassurance that workers occupationally exposed to styrene have not been exposed to a cancer risk (at the levels of exposure encountered by the members of this study).

The findings in (ii) will be somewhat reassuring, but further research may be required to clarify the carcinogenicity of styrene.

The findings in (iii), depending on the strength of any association found, may mean that further research is required to confirm the findings (this is often the case in occupational studies of this kind) or the findings may mean that a causal conclusion can be drawn that occupational exposure to styrene (at the levels encountered by the study participants) are associated with an increased risk of cancer.

For current workers, it will depend whether current exposure levels are at or above those associated with the increased cancer risk, as to how important the findings are. If current exposures are substantially lower, then appropriate reassurance can be provided however, if not, it could be that occupational exposure limits may need to be lowered and that further control of workplace exposures are required.

For those who have worked with styrene in the past or who continue to work with styrene, it is important to clarify whether such workers have been exposed to a carcinogenic hazard, for the reasons mentioned above. The UK part of the study is funded by the HSE and they will determine the relevance of any findings from a UK regulatory point of view.

In line with IOM’s legitimate interest for processing the data, workers in the industry, management, trades unions and regulators are expected to receive the benefit of the processing. If this work provides evidence that styrene is carcinogenic, then regulators may need to review occupational exposure limits, and the management, trades unions and workers themselves may need to review their work practices to minimise any carcinogenic risks. The focus of research may shift from determining, whether or not styrene is carcinogenic, to what cancers does it cause, and what is the nature of any exposure-response relationships for the different cancer sites implicated.

This study is anticipated to help clarify whether or not occupational exposure to styrene increases a person’s risk of contracting cancer. This will have consequences for the classification, labelling, and packaging of styrene and styrene containing products. Modelling of quantitative exposure levels of styrene will allow risk assessment and may form the basis for revision of the current threshold limit values that are based on acute effects.

The dissemination plans are for the results to be published in the peer-reviewed scientific knowledge and so to add to the scientific evidence base of this important topic. The presentations at conferences allow interaction with fellow scientists, some of whom may have a direct interest in this topic. Production of the leaflet for industry allows senior officials within the industry and the workforce representatives and workforce to have a clear understanding of the outcomes and implications of the research. The findings are expected to be evaluated by regulators and by other influential bodies such as the World Health Organisation’s International Agency for Research on Cancer.

It is anticipated that the findings of the UK study will be available in 2023.

Not stated in the register.