1. WORKING FOR A HEALTHY FUTURE
A Review of the United Kingdom
Historical Hygiene Assessment (HHA)
of National Semiconductor UK
John W Cherrie and Karen Galea
INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org

2. 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

3. 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

4. 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

5. NSUK, Greenock, Scotland
4547 employed
before the end of
April 1999
• Wafer fabrication started in the early 1970s
• Many individuals from the local area employed in plant

6. 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

7. Plant history…

8. 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

9. 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

10. Shift work…

11. 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 imregnatingo-
ring seals
• 1990 process discontinued

12. 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

13. 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

14. Public response

15. 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