Goals of the worker safety, environmental regulatory management, and contamination control groups are too often considered to be unrelated, if not conflicting. A more positive approach would be to treat the groups as parts of a collaborative triad. For example, equipment design and process controls can have a mutually beneficial impact on all three programs. In addition, similar techniques are sometimes used to monitor safety, environmental, and product contamination. Since monitoring programs can be costly in terms of manpower, production resources, and testing budget, consolidation of effort or at least comparison of trends and findings can have economic benefits.
Enclosed processes, minimizing worker exposure
Efforts to automate and/or contain chemicals are sometimes impelled by regulatory constraints. Such changes are often resisted because they are typically accompanied by high initial costs in terms of capital equipment and engineering time. Once the project is complete, the process is often improved. No matter what part of the triad spearheads the change, it is productive to have all three groups work together. For example, a process involving cleaning with perchloroethylene in a vapor degreaser was changed to one using automated, enclosed equipment. Environmental regulatory requirements were the inspiration for the change. However, those involved in worker safety, environmental compliance, and product performance worked together beginning with the stages of brainstorming, equipment and chemical evaluation, through selection, and process implementation. The result was not only sharply reduced solvent emissions and very low worker exposure but also superior process consistency and improved performance.1
Process Monitoring
Aniline-based curing agents are used in the manufacture of high performance epoxies and polyurethanes. Methylene dianiline (MDA) is representative of this class of curing compounds. MDA has an exceedingly low vapor pressure; airborne contamination is not the issue. The product Q.A. people are interested in a surface free of contamination so that the next process can be conducted. Residual MDA on the surface might interact with organic coatings, altering the color or impacting adhesion.
Occupational safety people monitor MDA because it is a regulated carcinogen with a TLV2 of 0.01 ppm.3 It is rapidly adsorbed through the skin and may be adsorbed through gloves. The occupational safety people collect information; the Q.A. people collect information. Both groups are concerned about surface contamination and would benefit by sharing data.
Monitoring of strontium chromate paints offer another example of possible confluence, with emphasis on airborne contamination. Strontium chromate-based paints are used in corrosion protection for high performance aircraft. The TLV is 0.0005 mg/m3 (four times lower than beryllium). Product quality personnel are concerned that the paint is applied specifically. Product safety personnel are concerned with airborne contamination either during application or by sanding during removal. Because the allowable employee exposure level is so very low, monitoring by industrial hygienists can provide a valuable tool in process control. The surface cleanliness people should provide information to the occupational health people as to what is on the surface and as to what processes are intended.
Conclusions
It is not realistic to expect that a single monitoring program could be used for all three parts of the triad. The goals of monitoring programs for worker safety, environmental compliance, and product contamination minimization are quite different. For example, the OSHA standard for nuisance particulates is 10 mg/m3; tolerable levels for surface contamination may be orders of magnitude lower. At the same time, increased coordination in tracking of monitoring trends among the worker safety, environmental compliance, and product performance might be expected to be productive for all concerned.
You want to keep the process under control for worker safety, environmental quality, and product quality. Therefore, any trend away from the norm of any contaminant tracked for safety, environmental, or product quality issues could signal other impending issues. The data could profitably be shared among the three disciplines.
References:
1 Dowell et al. Presentation, International Thermal Spray Association, Las Vegas, NV (October, 2003).
2 Registered trademark, American Conference of Governmental Industrial Hygienists.
3 http://www.osha.gov/pls/shaweb/owadisp.show_
document?p_table=STA NDARDS&p_id=10081, OSHA Standard for Methylene Dianiline,1910.1050, particularly Appendix A.
