Documents Daniels, Robert D. 2 results

"OBJECTIVES:
To examine exposure-response relationships between surrogates of firefighting exposure and select outcomes among previously studied US career firefighters.
METHODS:
Eight cancer and four non-cancer outcomes were examined using conditional logistic regression. Incidence density sampling was used to match each case to 200 controls on attained age. Days accrued in firefighting assignments (exposed-days), run totals (fire-runs) and run times (fire-hours) were used as exposure surrogates. HRs comparing 75th and 25th centiles of lagged cumulative exposures were calculated using loglinear, linear, log-quadratic, power and restricted cubic spline general relative risk models. Piecewise constant models were used to examine risk differences by time since exposure, age at exposure and calendar period.
RESULTS:
Among 19?309 male firefighters eligible for the study, there were 1333 cancer deaths and 2609 cancer incidence cases. Significant positive associations between fire-hours and lung cancer mortality and incidence were evident. A similar relation between leukaemia mortality and fire-runs was also found. The lung cancer associations were nearly linear in cumulative exposure, while the association with leukaemia mortality was attenuated at higher exposure levels and greater for recent exposures. Significant negative associations were evident for the exposure surrogates and colorectal and prostate cancers, suggesting a healthy worker survivor effect possibly enhanced by medical screening.
CONCLUSIONS:
Lung cancer and leukaemia mortality risks were modestly increasing with firefighter exposures. These findings add to evidence of a causal association between firefighting and cancer. Nevertheless, small effects merit cautious interpretation. We plan to continue to follow the occurrence of disease and injury in this cohort."

"The aetiology of chronic lymphocytic leukaemia (CLL) is largely unknown. Despite compelling evidence for ionising radiation as a cause of most forms of leukaemia, CLL was not found to be radiogenic in early studies. Herein we describe the recent evidence for causation of CLL by ionising and non-ionising radiation, including a nested case-control study conducted within a cohort of 94 517 US workers at four nuclear weapons facilities and a nuclear naval shipyard. Forty-three cases of CLL deaths and 172 age-matched controls were identified with follow-up up to between 1990 and 1996. Radiation exposure from external sources and plutonium (lagged 10 years) was assessed for each worker, based on monitoring records. The excess relative rate (ERR) was estimated for workers receiving elevated doses compared to unexposed workers, controlling for possible risk factors. The ERR per 10 mSv was -0.020 (95% confidence interval: <0, 0.14) based on all exposed workers. However, for workers receiving <100 mSv, the ERR per 10 mSv was 0.20 (-0.035, 0.96). Recent studies of uranium miners and other populations have shown elevations of CLL possibly associated with ionising and non-ionising radiation. New studies should use incident cases and sufficient latency to account for the expected lengthy induction period for CLL."