Arsenic and non-malignant lung disease

Abstract

Many aquifers in various parts of the world have been found to be contaminated with arsenic at concentration above 0.05 mg/L. However reports of large number of affected people in India and Bangladesh are unprecedented. Characteristic skin lesions (pigmentation, depigmentation and keratosis) are the hallmark signs of chronic arsenic toxicity. Emerging evidences show that ingestion of arsenic through drinking water may also lead to non-malignant respiratory effects. Early report of non-malignant pulmonary effect of chronic ingestion of arsenic was available from studies in children in Chile as early as 1970. However on the basis of case studies, respiratory effect of chronic arsenic toxicity in adults following dinking of arsenic contaminated water in West Bengal was first reported in 1997. Epidemiological studies carried out in West Bengal on a population of 7683 showed that the prevalence odds ratio (POR) estimates were markedly increased for participants with arsenic induced skin lesions who also had high levels of arsenic in their current drinking water source (≥0.5 mg/L) compared with individuals who had normal skin and were exposed to low levels of arsenic (< 0.05 mg/L). In participants with skin lesions, age-adjusted POR estimates for chronic cough were 7.8 for females (95% CI:3.1–19.5) and 5.0 for males (95% CI:2.6–9.9). In Bangladesh, similar study carried out on a population of 218 showed that the crude prevalence ratio for chronic bronchitis was found to be 10.3 (95% CI:2.4–43.1) for females and 1.6 (95% CI:0.8–3.1) for males. Reports of lung function tests were available from both hospital and population based studies. Results show evidences of restrictive, obstructive and combined obstructive and restrictive lung disease in different people having chronic lung disease associated with chronic arsenic toxicity. On the basis of clinical study, chest X-ray and HRCT done in Arsenicosis patients with features of chronic lung disease, the abnormalities observed were varied. Evidences of obstructive pulmonary disease (COPD), interstitial lung disease (ILD) and bronchiectasis were found in some of the cases. Results of studies carried out on people showing features of Arsenicosis due to drinking arsenic contaminated water provide evidence that arsenic is a potent respiratory toxicant, even following ingestion.

Keywords:

• Arsenic
• lung disease
• lung function tests
• chronic bronchitis
• COPD
• ILD
• bronchiectasis
• West Bengal

Notes

^#The following variables were added to the model one by one and were not found to confound the association with skin lesions: weight, occupation (service, farmer, other), education (no formal education, primary, secondary or higher), and type of house (mud, mixed materials, brick).

⁺FEV₁, forced expiratory volume in 1 second, CI, confidence interval FVC, forced vital capacity; FEF_{25− 75}, forced expiratory flow between 25% and 75% of forced vital capacity.

* Two-tailed.

^{$ $} Continuous variable.

^$ Smoking was defined as ever smoking versus never smoking. Different smoking variables, including pact-years of smoking, were also incorporated into the models but had no effect on the skin lesion result.

*Only those subjects with chronic cough underwent CT. Thus, bronchiectasis was defined as present when a subject had both chronic cough and bronchiectasis on CT. Bronchiectasis was defined as absent in subjects who did not have chronic cough and in subjects with chronic cough who did not have bronchiectasis on CT.

⁺Adjusted for age (year), gender, smoking (ever smoker versus never smoker), and self-reported history of physician-diagnosed tuberculosis (yes or no).

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