Silicate pneumoconiosis in hens

Thirteen cases of silicate pneumoconiosis in 3- to 4-year-old hens are desc ribed. Ten of the birds were raised in the suburbs of a city near several c halk quarries and two cement-works; the remaining three hens (aged 3 years) had lived in an environment with high particulate pollution from a nearby brick-works in which large amounts of clay were used daily. Silicotic granu lomas composed of dust-laden macrophages were scattered over the lungs. The y were located mainly in the infundibula and atria of tertiary bronchi and around vessels; more rarely they occurred in the lamina propria mucosae of primary and secondary bronchi. Energy dispersive x-ray microanalysis couple d with both transmission and scanning electron microscopy revealed that the dust was composed mainly of silicon, aluminium, calcium, iron and potassiu m. Titanium, sulphur, magnesium, zinc, copper and chlorine were also found. It is concluded that animals raised in polluted environmental conditions m ay serve as an important indicator of risks to human health and pathogeneti c mechanisms. (C) 2000 Harcourt Publishers Ltd.