and safety protections required to be provided to nonlaboratory employees.

Many organizations, faced with the difficulty of designing EHS programs that meet both the requirements of the Laboratory Standard and the requirements of the Hazard Communication Standard, have opted to follow the requirements of the Hazard Communication Standard for all workplaces, laboratory and nonlaboratory, while additionally adopting and implementing the Chemical Hygiene Plan requirements of the Laboratory Standard as they apply to laboratories. Careful comparison of the two standards should be made when designing an EHS program.

11.A.2.4 PELs, TLVs, and RELs

OSHA has developed PELs for chemicals. These are enforceable regulatory limits for the air concentration of individual substances to which a worker may be exposed. Many PELs are based on TLVs, which are nonregulatory exposure limits prepared by ACGIH using existing published, peer-reviewed scientific literature. Quoting the TLV booklet (ACGIH, 2009), “The TLVs … represent conditions under which ACGIH believes that nearly all workers may be repeatedly exposed without adverse health effects. They are not fine lines between safe and dangerous exposures, nor are they a relative index of toxicology.” PELs and TLVs are average concentrations for a normal 8-hour workday and a 40-hour workweek. This time-weighted average (TWA) approach to evaluating airborne contaminant exposure means that some periods of the day may have higher or lower exposures than others, reflecting the variability in most work with chemicals.

For a small number of compounds, both OSHA and ACGIH have also established a short-term exposure limit (STEL), a concentration considered safe for no more than four 15-minute periods a day. STELs are published only for compounds where toxic effects have been reported from high-level, short-duration exposures in humans or animals. In addition, both groups have also established ceiling limits for some compounds (indicated by a “C” preceding the TLV or PEL value). The ceiling limit is the concentration that should not be exceeded during any time portion of exposure. For compounds that include neither a STEL nor a C notation, a limit on the upper level of exposure should still be imposed. According to the TLV booklet, “Excursions in worker exposure levels may exceed 3 times the TLV-TWA for no more than a total of 30 minutes during a work day, and under no circumstances should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded.”

The action level (AL) is an OSHA regulatory concept applied to only a few substances. The AL is also an exposure limit for airborne concentration (lower than its associated PEL) that, if exceeded, requires certain additional protective measures to be implemented, such as additional confirmatory exposure monitoring, training, or medical surveillance. Although personal exposures in research laboratory environments are generally controlled well below all of these limits by the use of local exhaust devices and room air change rates, laboratories working with any of the chemicals covered by an OSHA substance-specific standard must be aware of the applicable regulatory provisions and implement them.

RELs are additional exposure values that are developed by the National Institute for Occupational Safety and Health (NIOSH). Like TLVs, RELs are not legal standards but are science-based recommendations that do not need to take into account feasibility, financial impact, or other consequences of their use. As a result, RELs and TLVs are generally more conservative (i.e., lower, more protective) than OSHA’s limits.

11.A.3 Understanding Other Laboratory Safety Requirements

These rules are vast, complex, and intricate in their details and interrelationships. As noted above, the application and specifics of federal laws vary from state to state, local jurisdictions, and among federal regulatory agency regional offices. Further, there is a great variety of state and local laws, and so requirements depend on the laboratory’s location. State and local laws are not covered here, and so specific requirements may vary from the general information provided here. Where available, an EHS officer who is familiar with the details of these rules can act as a resource for scientists. Smaller organizations can seek advice directly from their counsel, insurance provider, regulatory agencies, EHS professionals at other organizations, or consultants.

Table 11.1 lists safety laws that pertain to laboratories, along with their associated regulations. This table is not comprehensive. As noted previously, a detailed explanation of these requirements, and all the nonregulatory safety standards that apply to laboratories, is beyond the scope of this book. Laboratory safety standards that are among the most relevant are those published by the American Industrial Hygiene Association, American National Standards Institute (ANSI; e.g., laboratory decommissioning standard), Clinical and Laboratory Standards Institute (e.g., clinical laboratory waste management), College of American Pathologists, International Association for Assessment and Accreditation of Laboratory Animal Care, and the National Council on Radiation Protection and Measurement (e.g., radiation exposure, waste manage-



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