Engineering and public health at CDC.

Engineering is the application of scientific and technical knowledge to solve human problems. Using imagination, judgment, and reasoning to apply science, technology, mathematics, and practical experience, engineers develop the design, production, and operation of useful objects or processes. During the 1940s, engineers dominated the ranks of CDC scientists. In fact, the first CDC director, Assistant Surgeon General Mark Hollis, was an engineer. CDC engineers were involved in malaria control through the elimination of standing water. Eventually the CDC mission expanded to include prevention and control of dengue, typhus, and other communicable diseases. The development of chlorination, water filtration, and sewage treatment were crucial to preventing waterborne illness. Beginning in the 1950s, CDC engineers began their work to improve public health while developing the fields of environmental health, industrial hygiene, and control of air pollution. Engineering disciplines represented at CDC today include biomedical, civil, chemical, electrical, industrial, mechanical, mining, and safety engineering. Most CDC engineers are located in the National Institute for Occupational Safety and Health (NIOSH) and the Agency for Toxic Substances and Disease Registry (ATSDR). Engineering research at CDC has a broad stakeholder base. With the cooperation of industry, labor, trade associations, and other stakeholders and partners, current work includes studies of air contaminants, mining, safety, physical agents, ergonomics, and environmental hazards. Engineering solutions remain a cornerstone of the traditional "hierarchy of controls" approach to reducing public health hazards.

Gas and vapor exposure assessment methods.

Developing methods for making exposure assessment measurements for gases and vapors is a well-developed, active research field. Industry, academia, and government agencies have worked in this field for several decades, resulting in many sampling and analytical methods for gases and vapors for use in occupational, environmental, and indoor air applications. Consensus groups such as the International Standards Organization (ISO) and the American Society for Testing and Materials (ASTM) have contributed to the standard (methods) bank as well. There is much being done and much remaining to be done in methods development for gases and vapors. Additionally, consideration is now being given to issues like exposure to mixtures (noise and solvent vapors), mixed exposures (asphalt, diesel exhaust), and ethical acceptability--areas that before were, for a variety of reasons, largely ignored. This presentation focuses on method availability for exposure assessment, on research opportunities relative to gas and vapor analytical methods, and on avenues for accomplishing such work, and discusses some of the newer considerations for developing methods for exposure assessment.

Monitoring methodology for gaseous hazards. Passive monitors and portable instruments.

Reliable sampling and analytical procedures for monitoring workplace hazards must be developed and evaluated. In the present communication three studies involving the evaluation and development of personal monitoring techniques were presented. The first study described an evaluation of three passive monitors for organic solvent vapors. Toluene, trichloroethylene, n-hexane, acetone, methylene chloride, and vinyl chloride, each at three concentrations, as well as effects of temperature, humidity, linear adsorption capacity, variable concentration, complex solvent mixture, and storage time, were addressed. The results indicated that under specified conditions passive monitors are viable monitoring methods. The second study was an evaluation of two carbon monoxide dosimeters. Instrument accuracy, precision, and performance under a variety of experimental conditions were examined. Sufficient samples were taken to show that the Energetics Science series 9000 dosimeter was within +/- 25% of the true value 95% of the time. The General Electric model 15ECS1CO2 did not meet this same criterion. The third study describes the development of a unique sampling method for nitrogen dioxide using Poroplastic film impregnated with the absorbing liquid and a spacing material which allows for airflow and distribution to the absorber. The overall method, evaluated over the concentration range of 0.9 to 19 micrograms/1 in 36-1 samples, had an average bias of 7% with a coefficient of variation of 10%.