Lung Function in Men Exposed to Hazardous Asbestos and the Protective Effect of Beta Carotene

There is a substantial correlation between exposure to asbestos and the development of mesothelioma, but what is less understood is the protective effect that beta carotene can have on loss of lung function.  One interesting study is called that examines this issue is called, "The protective effect of beta-carotene and retinol on ventilatory function in an asbestos-exposed cohort" by P Chuwers, S Barnhart, P Blanc, CA Brodkin, M Cullen, T Kelly, J Keogh, G Omenn, J Williams and JR Balmes - Department of Medicine, University of California, San Francisco 94143- 0843 - Am. J. Respir. Crit. Care Med., Vol 155, No. 3, 03 1997, 1066-1071. Here is an excerpt: "The association between serum beta-carotene or retinol concentration and level of ventilatory function was investigated in a population of asbestos-exposed men with a high rate of current and former cigarette smoking. The study population consisted of 816 subjects enrolled in the pilot component of the Carotene and Retinol Efficacy Trial (CARET), a placebo-controlled trial of supplemental beta-carotene and retinyl palmitate for the chemoprevention of lung cancer. Data available for analysis included baseline questionnaire, spirometry, chest X-ray, food frequency questionnaire, and serum beta-carotene and retinol concentrations. Serum beta-carotene concentration was associated with FEV1 (p < 0.05) and FVC (p < 0.05), with an approximately 100-ml increase over predicted values associated with raising the serum concentration from the 25th to the 75th percentile of the distribution in the study population (absolute difference = 155 ng/ml), even after adjustment for the confounding effects of asbestos exposure and cigarette smoking. Raising the serum retinol concentration from the 25th to the 75th percentile (absolute difference = 211 ng/ml) was associated with an approximately 70 ml increase in FVC (p < 0.05) over the predicted value. These results provide support for the hypothesis that beta-carotene and retinol have a protective effect on loss of ventilatory function."

Another interesting study is called, "Asbestos, smoking, and laryngeal carcinoma." By Shettigara PT, Morgan RW - Arch Environ Health. 1975 Oct;30(10):517-9.  Here is an excerpt: "Abstract - This study was designed to examine the relationship between exposure to asbestos and laryngeal cancer. A retrospective study of 43 pairs of patients with laryngeal cancer and their matched controls examined a number of variables, including smoking, exposure to asbestos, and other occupational factors. Patients with laryngeal cancer and the controls were matched for age, sex, and place of residence. The data indicate a substantial association between asbestos exposure and laryngeal cancer. Cigarette smoking was also associated with the disease, although the strength of association was not as high as that for asbestos. Exposure to uranium, chromium, nickel, cobalt, arsenic, x-rays, and alcohol did not appear related to later development of carcinoma of the larynx. We conclude that exposure to asbestos and cigarette smoking are potent factors in the development of this disease."

Another interesting study is called, "Occupational respiratory cancer and exposure to asbestos: A case-control study in a cohort of workers in the electricity and gas industry" by E. Imbernon, MD, MSc, M. Goldberg, MD, PhD 1, S. Bonenfant, MSc, A. Chevalier, PhD, P. Guénel, MD, PhD, R. Vatré, MSc, J. Dehaye, MD - American Journal of Industrial Medicine - Volume 28 Issue 3, Pages 339 – 352.  Here is an excerpt: "Abstract - Cancers of the pleura, lung, and larynx between 1978 and 1989 among active male workers of Electricité de France-Gaz de France were studied in association with asbestos exposure using a case-control design nested within the cohort of workers of the company. The cohort included about 1,400,000 person-years, corresponding to a mean of 117,000 men per year. Exposure to asbestos and to some potential occupational confounders selected among agents from groups I, IIa, and IIb of the International Agency for Research on Cancer was assessed by a job-exposure matrix specific to the company. During the observation period, 12 cases of pleural cancer, 310 cases of lung cancer, and 116 cases of larynx cancer were registered in the cancer register of the company social security department. Four controls per case, matched for year of birth, were randomly selected among the cohort. Conditional logistic regression was used to estimate the odds ratios. A first analysis was conducted in order to assess the validity of the job-exposure matrix by investigating already known relationships between asbestos exposure and asbestosis. For asbestosis, a strong exposure-response relation was found with an odds ratio (OR) of 57.4 [95% confidence interval (CI): 17.0-194.0] in the highest exposure group. There was an elevated risk of pleural cancer (OR, 4.8, CI, 1.2-19.8). For lung cancer, significant ORs of 2.0 (CI, 1.3-3.2) and 1.9 (CI, 1.2-3.0) were found among the two highest cumulative exposure groups; adjustement for confounders slightly decreased the ORs. Squamous cell neoplasm of the lung was associated with asbestos exposure. The association between larynx cancer and asbestos exposure showed a tendency towards a nonsignificant increase in ORs in the highest cumulative exposure categories; this tendency disappeared when adjusting for occupational confounders. This study showed that occupational exposure to asbestos could increase the risk of pleural and lung cancer in a sector in which exposure levels are not considered to be high compared with other industrial settings."

If you found any of these excerpts, please read them in their entirety.  We all owe a debt of gratitude to these researchers.