Changing approaches to assessment of environmental inhalation risk: a case study

Area of Science:

• Environmental Science and Toxicology
• Occupational Health and Safety
• Industrial Hygiene

Background:

• Historical approaches to asbestos inhalation risk assessment focused on both particles and fibers.
• Understanding of asbestos health risks evolved, recognizing its role in causing both fibrosis and cancer.
• Technological advancements and new biological data have driven changes in risk assessment methodologies.

Purpose of the Study:

• To illustrate the profound changes in asbestos inhalation risk assessment over the past 60 years.
• To demonstrate the close relationship between scientific knowledge, technological capabilities, and policy decisions for toxic substance control.
• To highlight the iterative nature of policy making in response to evolving scientific understanding of asbestos risks.

Main Methods:

• Review of historical air-sampling instruments and measurement techniques for asbestos fibers.
• Analysis of the impact of new biological data and understanding of asbestos-related diseases (asbestosis, cancer).
• Examination of the role of regulatory imperatives and scientific assumptions (e.g., linear non-threshold dose-response) in setting exposure standards.

Main Results:

• Shift from measuring particles and fibers to focusing solely on fibers as understanding of asbestos airborne forms improved.
• The acceptance of asbestos as a carcinogen (no-threshold assumption) influenced workplace standards, leading to reductions by OSHA.
• Scientific and technical knowledge directly informed policy decisions and control strategies for asbestos exposure.

Conclusions:

• Effective control of toxic substances like asbestos relies on valid scientific risk estimates and precise measurement techniques.
• Policy-making for toxicant control should be an iterative process, becoming more restrictive as scientific knowledge advances.
• Regulation, rather than science alone, often serves as the primary driver for implementing controls on hazardous materials in the workplace.