Box 60.2Economic Evaluation of an Engineering Control for Silica Dust in India

The agate industry is a cottage industry concentrated in residential settings in Khambhat and Dahegam, in the state of Gujarat, India, where 15,000 grinders and 60,000 other workers, family members, and neighbors are exposed to silica dust. The making of key chains, necklaces, and art pieces involves baking, chipping, grinding, and polishing agate stones. The grinding-machine wheels are driven at speeds of 1,440 rpm, generating large amounts of dust containing respirable silica. The table shows the extraordinary prevalence in the total exposed populations (noted above) of silicosis and tuberculosis caused by silica exposure.

Prevalence of Diseases in Agate-dominated Areas of Khambat and Dahegam

SilicosisTuberculosisa
CategoryPercentNumberPercentNumber
Grinders304,500365,400
Nongrinding workers, family, and neighbors84,800169,600

Source: Bhagia, Ramnath, and Saiyed 2003.

a. National tuberculosis prevalence in India of 4 percent and resulting cases have been subtracted.

The National Institute of Occupational Health in India designed and distributed 10 dust control devices for the grinding machines to employers, who generally employ 5 to 10 workers (see figure). The efficacy of the devices was found to be 93 percent, and dust was greatly reduced (Bhagia, Ramnath, and Saiyed 2003). Economic analysis was based on 600 dust control devices that could be installed in the communities. The total costs include the initial one-time cost of the devices (Rs 8,000, or approximately US$92); depreciation (10 percent per year); maintenance of machines (equivalent to the costs saved by recycling the dust to be used in polishing); and the cost of treating the diseases (about Rs 4,000, or approximately US$184 per year per case). The gains included annual income per avoided case of silicosis. Total savings per year were estimated to be between Rs 23 million and Rs 29 million (US$527,039 to US$664,528). The conclusion is that installation of dust control devices in all the agate-grinding units of Gujarat would reduce silicosis and tuberculosis as well as yield financial and health benefits to the workers, families, and the greater society that bears the cost of illness.

Image

Figure

Traditional Grinding Machine with Dust Control System

From: Chapter 60, Occupational Health

Cover of Disease Control Priorities in Developing Countries
Disease Control Priorities in Developing Countries. 2nd edition.
Jamison DT, Breman JG, Measham AR, et al., editors.
Copyright © 2006, The International Bank for Reconstruction and Development/The World Bank Group.

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