tailieunhanh - BASIC HAZARDOUS WASTE MANAGEMENT - CHAPTER 4

Chất độc và quá trình thiết lập tiêu chuẩn MỤC TIÊU Hoàn thành chương này, học sinh nên: • Hiểu được cơ chế cơ bản của con người tiếp xúc. • Có thể liên quan các cơ chế tiếp xúc với các con đường overviewed trong Chương 3 và các cơ chế phát hành phổ biến. • Hãy có thể xác định vị trí các dữ liệu thích hợp trên các chất độc của các thành phần hóa học của chất thải nguy hại. • Biết các thành phần của quá trình đánh giá nguy cơ nói chung và hiểu được mối. | 4 Toxicology and the Standard-Setting Processes OBJECTIVES At completion of this chapter the student should Understand the basic mechanisms of human exposure. Be able to relate the exposure mechanisms to the pathways overviewed in Chapter 3 and to the common release mechanisms. Be able to locate appropriate data on the toxicology of the chemical constituents of hazardous wastes. Know the components of the general risk assessment process and understand their relationship to each other. Understand how toxicological and human health considerations have been addressed in RCRA and how RCRA measures regulates and attempts to minimize toxic and health impacts of hazardous wastes. INTRODUCTION Living organisms are composed of cells and all cells must accommodate and facilitate a variety of chemical reactions to maintain themselves and perform their functions. Introduction of a foreign chemical into a cell may interfere with one or more of these cellular reactions leading to impaired cell function or viability. All chemicals are toxic but the concentration route of entry and time of exposure are factors that determine the degree of toxic effect. Toxicology is the study of how specific chemicals cause injury to living cells and whole organisms. Such studies are performed to determine how easily the chemical enters the organism how it behaves inside the organism how rapidly it is removed from the organism what cells are affected by the chemical and what cell functions are impaired. A risk assessment process is used to derive a reliable estimate of the amount of chemical exposure which is considered acceptable for humans or other organisms. Risk-based exposure limits are then rationalized in the form of risk-based standards. The alternative form of exposure limits is the technology-based standard in which the goal is to minimize exposure by the imposition of control technologies. 2001 by CRC Press LLC In recent years important advances have been achieved in toxicology and in .