Laboratory hazard levels

Note These hazard levels are not to be confused with the DOE classification of nuclear waste into high-level, low-level, mixed low-level, transuranic and 1 le(2) byproduct material categories. These nuclear waste categories are established by DOE Order 5820.2A, which can be viewed online at http //www.directives.doe.gov (Dec. 2005). See DOE/EM (1997) for more information on nuclear waste. To reiterate, waste hazard levels are different than laboratory hazard levels, although the defining terminology is similar. 

The contractor at Site H had established area and personnel sampling consistent with HAZWOPER requirements. A photo ionization detector (PID) and a real-time aerosol monitor (RAM) were used on a daily basis to screen for potentially hazardous levels of contaminants. On a weekly basis, personal air samples were collected and submitted for laboratory analysis. PPE requirements, however, were often not based on this data because the oversight agency had established inflexible minimum PPE requirements. The audit team found many of the PPE requirements on Site H to be excessive in light of site monitoring data and hazard determinations. 

Field and laboratory studies were conducted to determine the levels of Cd, Pb, and HCBD in various samples collected from a swamp environment in Louisiana and to assess the toxicities of As, Cd, and Hg to two species of aquatic organisms (bluegills and crawfish) indigenous to this swamp [18]. Cadmium and Pb were present in almost all collected samples. Their concentrations in fish were below the action levels set by EPA for the protection of human health. However, hazardous levels of these two elements were found in samples of crawfish, vegetation, soil, sediment, and water to some extent. Low levels of HCBD were recorded in water and sediment samples. In bioassay studies, Hg was found to be the most toxic metal, while As was the least toxic. Between the two test organisms, blue-gills appeared to be more sensitive than crawfish. Mixtures of Cd with As or Hg resulted in a combined toxic effect which was simply additive. However, a synergistic effect was recorded with the mixtures of As and Hg. 

Recognize that a more dilute acid, base, oxidizer, or reducer presents a lower hazard level and requires a lower level of protection in the laboratory. 

This hazard level will be reduced if not totally removed when commercial instrumentation is made available to the laboratory community in the near future. By the same token, when such instrumentation is available even better operating conditions will be available to users as the apparatus and peripherals used therefor will have been designed specifically for that purpose keeping the critical parameters in mind. 

A primary consideration in laboratory design is the magnitude of the radioactivity in the samples that the laboratory will process. The Department of Energy has designated four hazard levels for radiological samples ... 

Mercury is a particular problem for the DOE because it is found at hazardous levels at several large DOE sites and results in extensive conUimination of associated water resources. One site in particular, at Oak Ridge National Laboratories, still contains millions of pounds of mercury spread over miles of a river valley even after extensive and costly physical remediation efforts of excavation and reburial off site. 

FIGURE 3.1.2.3 NFPA Diamond. The fire diamond is frequently used in chemical laboratories. The ratings indicate the hazard level under fire conditions, not necessarily ambient laboratory conditions. (The NFPA diamond is reprinted with permission from NFPA 704-2007, System for the Identification of the Hazards of Materials for Emergency Response. Copyright 2007 National Fire Protection Association, Quincy, MA. This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety. The NFPA classifies a limited number of chemicals and cannot be responsible for the classification of any chemical whether the hazard of classifications are included in NFPA or developed by other individuals.)... 

HO DECIDES what s safe And how do they make that determination Another principle of safety is assessing the risks of hazards. Understanding how we each view risk affects how we behave in the laboratory, and affects how we interpret safety information. Not everyone makes the same choice given a set of dangers and options. This chapter is about the process of risk assessment and the means by which scientists share information about hazard levels posed by chemicals. Students involved in research projects have to learn to develop their sense of judgment about risk as they plan and conduct experiments. Will you know how to decide what s safe when presented with the design of a new experiment ... 

Assess the level of risk presented by the laboratory hazards by making your own judgments, rather than trusting the past experiences of others. 

In the laboratory you may be exposed to instruments that generate radiation (such as X-ray diffraction instruments) or may have sealed sources that contain hazardous levels of radioactive materials (such as Y irradiators or analytical detectors). You may also be exposed to unsealed, open sources of radiation. Both types require special training and education to learn proper procedures and handling precautions about these radiation hazards. We discuss first how to protect yourself from sources of radiation in laboratory instrumentation. 

FIGURE 3.1.2.6 Laboratory Chemical Bottle with NFPA Diamond. It is important to know the meaning of the ratings (0-4) in the fire diamond to properly assess the various hazard levels of health, flammability, and reactivity. 

Typical units for LDjq values are milligrams or grams of material per kilogram of body weight (mg/kg or g/kg, recall that 1 kg = 2.2 pounds). Never be exposed to an LD50 dose of a hazardous chemical- by definition, there is a 50% chance this will kill you and if you survive you are not going to be in good shape. Pay close attention to the permissible exposure level (PEL) instead. This is a more realistic determination of the maximum safe exposure to a material and is usually based on the known effects of the chemical on humans, rather than laboratory animals. 

The effectiveness of incineration has most commonly been estimated from the heating value of the fuel, a parameter that has little to do with the rate or mechanism of destraction. Alternative ways to assess the effectiveness of incineration destraction of various constituents of a hazardous waste stream have been proposed, such as assessment methods based on the kinetics of thermal decomposition of the constituents or on the susceptibility of individual constituents to free-radical attack. Laboratory studies of waste incineration have demonstrated that no single ranking procedure is appropriate for all incinerator conditions. For example, acceptably low levels of some test compounds, such as methylene chloride, have proved difficult to achieve because these compounds are formed in the flame from other chemical species. 

A janitor surrounded by sensitive instruments may be like a bull in a china shop. In one laboratory, the janitors were not allowed to clean anything above floor level, including windows, without supervision by laboratory personnel. Janitors should not be allowed to handle containers of flammable or hazardous waste. Laboratory personnel should clear the floors completely when the janitor announces that it is time for floor waxing. 

---