Department of Public Health Sciences University of California at Davis, 1 Shields Ave., Davis, CA 95616, USA.
Proc Am Thorac Soc. 2010 May;7(2):107-10. doi: 10.1513/pats.200906-036RM.
Early studies of agricultural respiratory diseases focused on allergic disorders due to organic dust exposure. However, agricultural workers in dry climate regions are exposed to substantial concentrations of inorganic dusts from agricultural soils. Exposures to inorganic dusts are dependent on the specific crop and task, but are commonly several milligrams of respirable dust per cubic millimeter. In vitro toxicity studies show the dust's cytotoxicity to be intermediate between controls and crystalline silica. However, in some assays of reactive oxygen species generation, such as H(2)O(2), hydroxyl radical, and nuclear factor kappaB generation, the agricultural dusts are more potent than silica. A recent study of human lung samples among deceased Latino males characterized the deposition of agricultural dusts in the lung and the pulmonary response to these dusts. Careful histologic analyses in this study demonstrated that farmwork was significantly associated with mineral dust small airways disease and pneumoconiosis (macules and/or nodules). These associations persisted in multivariate analysis. Cigarette smoking was independently associated with these outcomes, but the interaction of mineral dust and smoking was not significant. Limited studies of farmworkers exposed to inorganic dusts show respiratory symptoms and restrictive pulmonary function with exposure. Overall, the evidence supports a causal association of mineral dust exposure and pneumoconiosis. Inorganic mineral dusts should no longer be considered merely a nuisance, but rather a cause of mixed-dust pneumoconiosis. The prevalence and natural history of this disorder are unknown.
早期的农业呼吸系统疾病研究主要集中在因有机粉尘暴露而导致的过敏疾病上。然而，在干燥气候地区的农业工作者会暴露于大量来自农业土壤的无机粉尘中。对无机粉尘的暴露取决于特定的作物和任务，但通常每立方毫米有几毫克可吸入的粉尘。体外毒性研究表明，粉尘的细胞毒性介于对照和结晶二氧化硅之间。然而，在一些活性氧物质生成的检测中，如 H(2)O(2)、羟基自由基和核因子 kappaB 的生成，农业粉尘比二氧化硅更为有效。最近一项对已故拉丁裔男性人体肺样本的研究描述了农业粉尘在肺部的沉积以及对这些粉尘的肺部反应。在这项研究中，对组织学进行了仔细分析，结果表明农业工作与矿物性粉尘小气道疾病和尘肺（斑和/或结节）有显著关联。这些关联在多变量分析中仍然存在。吸烟与这些结果独立相关，但矿物粉尘和吸烟之间的相互作用并不显著。对接触无机粉尘的农场工人进行的有限研究表明，接触会导致呼吸道症状和限制性肺功能。总的来说，证据支持矿物粉尘暴露与尘肺之间存在因果关系。无机矿物粉尘不应再被视为仅仅是一种滋扰，而应被视为混合粉尘尘肺的原因。这种疾病的流行程度和自然病史尚不清楚。
