Lung cancer incidence among an Icelandic cohort exposed to diatomaceous earth and cristobalite.

Abstract

OBJECTIVES:

The objective of this study was to determine the cancer incidence of a cohort exposed to diatomaceous earth and cristobalite with special focus on lung cancer.

METHODS:

The cohort was from a diatomaceous plant in northern Iceland and comprised 919 men and 423 women. Diatomite, when heated, is transformed from amorphous to crystalline silica with a high cristobalite content and traces of quartz. With the use of the identification number of all persons, a link was made with the Cancer Registry. The expected number of malignancies was calculated on the basis of person-years of observation for 5-year age categories during the respective calendar period of the study multiplied by the specific incidence of cancer site for men and women in Iceland.

RESULTS:

There was no increased overall incidence of cancer in the study population; 5 cases of lung cancer were observed versus 4.4 expected, the standardized incidence ratio (SIR) was 1.14 [95% confidence interval (95% CI) 0.37-2.65]. When the men in the cohort were divided according to their length of employment, there was an excess of lung cancer (3 observed versus 1.28 expected, SIR 2.34, 95% CI 0.48-6.85), nonmelanoma skin cancer (2 observed versus 0.19 expected, SIR 10.53, 95% CI 1.27-38.02), and brain cancer (3 observed versus 0.30 expected, SIR 10.00, 95% CI 2.06-29.23) for those who had worked 5 years or longer. A special investigation of smoking habits among the cohort revealed a smoking pattern similar to that of the general population.

CONCLUSION:

The results concerning lung cancer showed an excess risk for workers exposed to diatomaceous earth and cristobalite; the result was not, however, statistically significant. There was a trend towards a higher incidence of lung cancer with longer exposure to crystalline silica, and, in agreement with the results of a previous study from this industry, the findings indicate a causal relation.

• Authors: V Rafnsson, H Gunnarsdóttir
• Journal: Scandinavian journal of work, environment & health (Scand J Work Environ Health) Vol. 23 Issue 3 Pg. 187-92 (Jun 1997) ISSN: 0355-3140 [Print] Finland
• PMID: 9243728 (Publication Type: Journal Article)

Chemical References

• Air Pollutants
• Carcinogens, Environmental
• Diatomaceous Earth
• Silicon Dioxide

Topics

• Air Pollutants (adverse effects)
• Carcinogens, Environmental (adverse effects)
• Cohort Studies
• Confidence Intervals
• Diatomaceous Earth (adverse effects)
• Female
• Humans
• Iceland (epidemiology)
• Incidence
• Lung Neoplasms (epidemiology, etiology)
• Male
• Neoplasms (epidemiology)
• Occupational Exposure (adverse effects, statistics & numerical data)
• Registries
• Retrospective Studies
• Sex Distribution
• Silicon Dioxide (adverse effects)
• Smoking (epidemiology)
• Time Factors