纳米技术产品中的纳米材料具有未知的安全隐患和不可预期的风险。为保护人类健康与环境安全，有必要对纳米材料和纳米技术产品的生产及使用实行风险评估制度。同时，为加强对纳米技术产业的监管，需要对相关产品实行统一的认证注册制度。制定关于“纳米材料”的定义是建立这些制度的首要任务。在全面综述国际上已出台的纳米材料操作定义的基础上，从尺寸、内部结构、物理化学特性等角度对各种定义进行了对比分析。目前主要是通过寻找一个包容性的尺寸范围或者采用分层级描述的方法对纳米材料进行定义。两种方法都没有强调“纳米材料”定义作为具体法规的“强制性条款”时的不确定性。关于纳米材料需要出台一个更为详细的描述，以作为监管的法规性定义。该定义中包含的其他因素必须适用于所有可能的纳米材料。

There are unknown security risks and unexpected dangers when using the nanomaterials based and nanotech-enabled products. For the benefits of human health and the environment, it is necessary to conduct a risk assessment on the production and the application of nanomaterials and nanotech-enabled products. Moreover, a uniform regulation of registering the nanotech-enabled products can help supervise the nanotechnology industry. For both risk assessment and product register system, the definitions of nanomaterials are the primary requirement. Based on an overview of the existing various international working definitions of "nanomaterials", a comparison analysis is conducted with respect to size, internal structure, physical and chemical characteristics. So far, seeking an inclusive size range and using a hierarchical approach are two significant methods to define the nanomaterials. However, neither approaches actually address the associated uncertainties when the definitions of "nanomaterials" are requested for the use as "enforceable terms" in a specific regulatory setting. A more detailed regulatory definition should be introduced for supervision. The other factors included in the definition must apply to all nanomaterials.