the historical hygiene assessment of national semiconductor uk

WORKING FOR A HEALTHY FUTURE

INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org

A Review of the United Kingdom Historical Hygiene Assessment (HHA) of National Semiconductor UK

John W Cherrie and Karen Galea

Acknowledgements

• Work funded by the Health and Safety Executive (HSE)

• Part of an updated mortality study and “cluster analysis”• Principal Investigator Dr John Osman• Other collaborators: Brian G. Miller, Laura MacCalman,

Sam Wilkinson, Andrew J. Darnton, Amy Shafrir, Damien M. McElvenny

Summary…

• The main stimulus for the study• Outline of the plant history• Key processes carried out• Gender differences in exposures• Key exposures of interest• The results from the epidemiological

investigations

The stimulus for the study…

• Phase II pressure group• Results form a previous cohort

study undertaken by HSE• 11 female lung cancers

4 expected• 3 female stomach cancers

<1 expected• 4 male brain cancers

<1 expected• 20 female breast cancers

15 expected

NSUK, Greenock, Scotland

• Wafer fabrication started in the early 1970s• Many individuals from the local area employed in plant

4547 employed before the end of

April 1999

Methodology…

• Interviews with long-service employees and former employees• Nominated by company and pressure group

• Scrutiny of records, blueprints etc• Occupational hygiene measurement data• Details of ionising and non-ionising radiation sources• Details of Personal Protective Equipment (PPE) /

Respiratory Protective Equipment (RPE)• Smoking / health surveillance policies• Accident / incident reports• Shift pattern records

Plant history…

Possible exposure hazardous agents

• Shift work • Ionising and non-ionising radiation sources• Toxic metals • Toxic gases• Sulphuric and other acid mists• Various organic solvents• Asbestos (in buildings) and ceramic fibre

Gender differences…

• Originally all operators were female• The first male operators began in the mid-

1980s By the mid-1990s when there was equal numbers of males and females

• Supervisory, maintenance, lab technicians and engineering were predominantly male

• In the early-1990s in Fab 2, men worked on processes where propylene glycol methyl ether acetate was used

Shift work…

Ionising radiation

• Variety of sources, including sealed sources, high voltage x-ray sources and Krypton-85

• In 1983 tracer flow/leak test process started• Same year the dose rates from process exceeded

legal limits (Kr-85)• Additional shielding• In 1984 process redesigned

• 1986 further problems with Kr-85 imregnating o-ring seals

• 1990 process discontinued

Antimony and arsenic

• Antimony used in diffusion furnace operations• Measurements in 1982 showed levels well below OEL

• Arsenic used in diffusion furnaces, ion implanters (arsine), epitaxial reactors (arsine), vapour deposition reactors • Monitoring during process operations below OEL• Some maintenance tasks resulted in exposures above

OEL, but respirators used

Results from the epidemiological study

• SMRs for the three cancers of prior interest for women reduced in new follow-up

• No further brain cancers in men• Poor response rate from

subjects/proxies in cluster analysis• No consistent evidence that cases

more likely to be exposed to hazards than controls

Public response

Further information at…

• Leaflet summarising the findings of the follow-up study

• Main report for the follow-up study • Appendices to the main report • Detailed Historical Hygiene Assessment

• www.hse.gov.uk/statistics/publications/nsuk.htm