Cancer mortality in workers exposed to dieldrin and aldrin: over 50 years of follow up

OBJECTIVE

Dieldrin and aldrin, pesticides widely used until the 1970s, have been under suspicion of being carcinogenic. In this study, overall and cause-specific mortality was assessed in a cohort of 570 employees occupationally exposed to the pesticides dieldrin and aldrin to investigate the long-term health effects, in particular carcinogenic effects.

METHODS

All of the employees worked in the production plants between January 1954 and January 1970 and were followed for cause-specific mortality until 30 April 2006. Based on dieldrin levels in blood samples taken from 343 workers during the exposure period, the total intake of dieldrin was estimated for each individual subjects in the cohort. The estimated total intake ranged from 11 to 7,755 mg of dieldrin, with an average of 737 mg.

RESULTS

Two hundred and twenty-six workers had died before 30 April 2006 compared with an expected number of 327.3, giving a standardized mortality ratio (SMR) of 69.0 (95% confidence interval (CI): 60.3-78.7). Overall cancer mortality was also significantly lower than expected (SMR: 76.4, 95% CI: 60.8-94.9). Also, none of the specific cancer sites showed a significant excess mortality and no association between exposure level and cancer mortality was found.

CONCLUSION

The results from this study support findings from other epidemiological and recent animal studies concluding that dieldrin and aldrin are not likely human carcinogens.

Age at retirement and long term survival of an industrial population: prospective cohort study

OBJECTIVE

To assess whether early retirement is associated with better survival.

DESIGN

Long term prospective cohort study.

SETTING

Petroleum and petrochemical industry, United States.

SUBJECTS

Past employees of Shell Oil who retired at ages 55, 60, and 65 between 1 January 1973 and 31 December 2003.

MAIN OUTCOME MEASURE

Hazard ratio of death adjusted for sex, year of entry to study, and socioeconomic status.

RESULTS

Subjects who retired early at 55 and who were still alive at 65 had a significantly higher mortality than those who retired at 65 (hazard ratio 1.37, 95% confidence interval 1.09 to 1.73). Mortality was also significantly higher for subjects in the first 10 years after retirement at 55 compared with those who continued working (1.89, 1.58 to 2.27). After adjustment, mortality was similar between those who retired at 60 and those who retired at 65 (1.06, 0.92 to 1.22). Mortality did not differ for the first five years after retirement at 60 compared with continuing work at 60 (1.04, 0.82 to 1.31).

CONCLUSIONS

Retiring early at 55 or 60 was not associated with better survival than retiring at 65 in a cohort of past employees of the petrochemical industry. Mortality was higher in employees who retired at 55 than in those who continued working.

Cancer mortality in workers exposed to dieldrin and aldrin: an update

This study was conducted to investigate the possible long-term health effects, in particular carcinogenic effects, of occupational exposure to the organochlorine insecticides dieldrin and aldrin. We updated an earlier cohort mortality study of 570 employees involved in the production of these insecticides. All of the employees had worked in the production plants between 1 January 1954 and 1 January 1970 and were followed for cause-specific mortality until 1 January 2001. Based on dieldrin levels in blood samples taken during the exposure period, available for 343 workers, individual estimates of the total intake of dieldrin were estimated for all individual subjects in the cohort. The estimated total intake ranged from 11 to 7755 mg of dieldrin, with an average of 737 mg. One hundred and seventy-one workers had died before 1 January 2001, compared with an expected number of 226.6, giving a standardized mortality ratio (SMR) of 75.6 [95% confidence interval (CI): 64.6-87.7]. This deficit in total mortality was mainly attributable to a deficit in cardiovascular disease mortality, but cancer mortality was also lower than expected. The observed number of deaths from rectal cancer was significantly higher than expected (SMR = 300.0; 95% CI: 109.5-649.3), but was most pronounced in the low-intake subgroup and appears to be unrelated to exposure to dieldrin and aldrin. This study reinforces the earlier findings that occupational exposure of workers to significant amounts of dieldrin and aldrin has not led to a higher cancer mortality than would be found in an unexposed population.

Development and Implementation of an HSE Management System in Exploration and Production Companies

Summary

This paper describes the experience to date with safety management systems (SMS's) and describes their implementation after the Piper Alpha disaster and Lord Cullen's report. It also shows the gradual expansion of these systems toward fully integrated health, safety, and environment (HSE) management systems. Our company policy, which was clearly stated before publication of Lord Cullen's report, is that work should not start until the appropriate controls are in place. Work based on this policy and on objective-setting SMS's within Shell IntI. Petroleum Mij. (SIPM) E&P coordination started in earnest soon after the publication of the report in Nov. 1990 and has continued without interruption since that time. Objective-setting systems may be defined as systems where the company management sets its own objectives or goals on the basis of functional rather than prescriptive requirements and then goes on to demonstrate how such goals have been, or are being, met. The paper ends with a projection of what may be expected in the future.

Introduction

Following the Piper Alpha disaster and the in-depth public inquiry led by Lord Cullen, the recommendation was made that all offshore installations on the U.K. continental shelf should have safety cases similar to those already required under the U.K. Control of Industrial Major Accident Hazards Regulations. This recommendation was given effect by means of the safety-case regulation within the U.K. with a Nov. 1993 deadline for the submission of safety cases. Shell Expro, as a major operator in the U.K. sector of the North Sea, had already begun work on its safety cases before publication of the Cullen report and was one of the companies that contributed to the so called "voluntary" safety cases before this date.

It was apparent to E&P management within SIPM that the SMS and the safety case provided better assurance of safe operation and were of real value to Shell operations worldwide. (In this paper, Shell is sometimes used for E&P companies of the Royal Dutch/ Shell group in general, and Shell E&P is used if experience was gained through technical service agreements supported by SIPM E&P). It was also clear that a worldwide move toward such systems would take place. Thus, application of these systems was both good business and appropriate for all Shell E&P operating companies. As a direct consequence, an integrated project team (both project engineering and operations) was set up to implement SMS and safety cases throughout Shell upstream operations worldwide.