Development of Hazard Assessment System for Durable Suspended Particulute Matters

日本工业使用的化学物质约有5万种，同时每年有数百种以上的化学物质被开发出来，以满足多样化的需求。化学物质有助于工业发展和富裕生活方式的实现，因此它们已成为现代社会不可或缺的一部分。然而，许多这类物质是有害的，可能对健康不利，这取决于它们的处理方式，因此需要对它们进行充分管理。为了控制这些风险，有必要通过了解危害程度和暴露量来进行风险评估。在评估化学物质对人类健康的潜在危害时，法律要求进行致突变性试验或致癌性试验，但它们不是耐用颗粒物的有效试验方法。在持久性颗粒物中，有些，如典型的石棉和结晶二氧化硅，在接触后20至30年以上会诱发尘肺病、肺癌或间皮瘤。由于这增加了一些新开发物质具有类似危害的可能性，因此需要建立持久颗粒物的危害预测/评价系统。为了实现这一目标，系统地进行了五步试验，即物理和化学、体外、气管内滴注、短期和长期吸入试验。以结晶二氧化硅为阳性对照，使用的测试样品是由相同化学成分和需求量有望增加的碳化硅晶须组成的不同形状、纤维状和颗粒状的钛酸钾。通过对收集到的数据进行综合，建立了危害评价方法，并对数据进行归纳，建立了适用于所有持久性颗粒物的危害评价体系。这一结果特别提示了新化学物质的发展方向，因为它阐明了肺部颗粒在活性和生物持久性方面的差异，这取决于它们的形状。少

Approximately 50,000 kinds of chemical substances are used by Japanese industry while more than several hundreds are developed anew every year to meet the demands of diversification. Chemical substances contribute to industrial development and the realization of an affluent lifestyle and thus they have become indispensable to modern society. However, many such substances are harmful and may be adverse to health, depending on the way they are handled, and therefore they need to be adequately managed.To control these risks, it is necessary to perform risk assessment by comprehending the degree of hazard and the amount of exposure. Mutagenicity tests or carcinogenicity tests are legally required for evaluating the potential hazards of chemical substances on human health, but they are no valid testing methods for durable particulate matters.Among durable particulate matters, some, as typified by asbestos and crystalline silica, induce pneumoconiosis, lung cancer or mesothelioma twenty to t … More hirty years after the exposure. As this raises the possibility that some of the newly developed substances are similarly harmful, establishment of a hazard prediction/evaluation system for durable particulate matters is required. To achieve this goal, five-step tests have been systematically conducted, namely : physical and chemical, in vitro, intratracheal instillation, short-term and long-term inhalation tests. With crystalline silica as positive control, the test samples used were potassium titanate with different shapes, fibrous and particulate, composed of the same chemical components and silicon carbide whisker whose demand is expected to increase. The hazard assessment method has been established by integrating the obtained data while a system applicable to all the durable particulate matters has been developed by generalizing the data. The result was particularly suggestive of the direction for the development of new chemical substances by illuminating the difference in activity and biopersistence of the particles in the lung, depending on their shape. Less