The mortality (1955-2005) and
cancer morbidity experience (1971-2005) of a cohort of 363 male production workers exposed to MBT while employed at a chemical factory in north Wales were investigated. Two analytical approaches were used, indirect standardisation and Poisson regression.
RESULTS: Based on national mortality rates, significant excess mortality was found for
cancers of the large intestine (observed; Obs 8, standardised mortality ratio (SMR) 232, 95% CI 100 to 457) and bladder (Obs 8, SMR 374, 95% CI 162 to 737). Non-significant excesses were shown for
lung cancer (Obs 27, SMR 138, 95% CI 91 to 201) and
multiple myeloma (Obs 3, SMR 440, 95% CI 91 to 1287). Based on national
cancer incidence rates, significant excess morbidity was found for
cancer of the bladder (Obs 12, standardised registration ratio (SRR) 253, 95% CI 131 to 441) and
multiple myeloma (Obs 4, SRR 465, 95% CI 127 to 1191). Non-significant excesses were shown for
cancers of the large intestine (Obs 9, SRR 181, 95% CI 83 to 344) and lung (Obs 26, SRR 152, 95% CI 99 to 223). In analyses that included follow-up information on an additional 1797 plant employees not exposed to MBT, Poisson regression showed significant positive trends both for risks of
cancer of the large intestine and for risks of
multiple myeloma in relation to estimated cumulative exposure to MBT.
CONCLUSIONS: