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Blood cadmium concentrations in the general population of British middle-aged men
S J Pocock1, H T Delves, D Ashby
1Department of Clinical Epidemiology and General Practice, Royal Free Hospital School of Medicine, London, UK.
Insights
This study found that smoking significantly increases blood cadmium levels in middle-aged men. Geographic variations in cadmium levels also exist, warranting further investigation into environmental factors.
Area of Science:
- Environmental Health
- Toxicology
- Public Health
Background:
- Cadmium is a toxic heavy metal with potential health implications.
- Understanding cadmium exposure pathways is crucial for public health.
- Smoking is a known source of cadmium exposure.
Purpose of the Study:
- To determine blood cadmium concentrations in a large cohort of middle-aged British men.
- To investigate the relationship between smoking habits and blood cadmium levels.
- To explore geographic variations in blood cadmium concentrations.
Main Methods:
- Randomly selected 6919 men aged 40-59 from general practice registers across 24 British towns.
- Measured blood cadmium concentrations.
- Analyzed data considering smoking status, daily cigarette consumption, age, social class, and alcohol consumption.
Main Results:
- Mean blood cadmium was 1.9 µg/l, with significant elevation in current smokers (mean 3.9 µg/l for heavy smokers).
- 95% of non-smokers had <2.0 µg/l, while 80% of heavy smokers exceeded this.
- Ex-smokers had lower levels than current smokers but higher than non-smokers for years.
- Substantial geographic variation observed, with higher levels in most towns outside SE England.
Conclusions:
- Cigarette smoking is the primary determinant of elevated blood cadmium in middle-aged men.
- Geographic differences in blood cadmium levels suggest environmental factors beyond smoking require further study.
- Public health strategies should focus on smoking cessation and investigating environmental cadmium sources.
Abstract:
Blood cadmium concentrations were determined for 6919 men aged 40-59 randomly selected from general practice registers in 24 British towns. The mean and median blood cadmium were 1.9 and 1.4 micrograms/1 respectively and the distribution was highly skewed. The mean levels in non-smokers was 1.0 micrograms/l and current smokers showed a marked gradient with the daily amount smoked, with a mean of 3.9 micrograms/l in men smoking 40 or more cigarettes per day. Whereas 95% of men who never smoked had blood cadmium less than 2.0 micrograms/l, 80% of men smoking 20 or more cigarettes a day exceeded this figure. 1% of the men had blood cadmium concentrations greater than or equal to 7 micrograms/l virtually all of whom currently smoked cigarettes. Blood cadmium levels in ex-smokers were much lower than in current smokers even for those who had stopped within the past year. However, the mean levels in ex-smokers remained higher than the 'never smoked' for several years after stopping. There was little evidence that age, social class, or alcohol consumption were associated with blood cadmium levels after allowance for cigarette smoking. There is substantial geographic variation in mean blood cadmium for middle-aged men which could not be completely accounted for by smoking differences. Towns in the south and east of England all had mean levels under 2.0 micrograms/l whereas the majority of towns in other parts of Britain had mean levels greater than 2.0 micrograms/l. Possible reasons for this geographic pattern (e.g. geochemistry, industrial exposure, dietary differences) need further exploration.