Toxic Materials Handling in the Laboratory

Below are definitions of the classes of chemicals that are considered highly hazardous.

Substances with a high degree of acute toxicity are those that can cause death, disability, or serious injury after a single, relatively low-level exposure.

Toxins are chemicals created by plants, animals or microorganisms that are poisonous to humans. Certain toxins have been listed as Select Agent Toxins by the Centers for Disease Control (CDC). The University is required to register these toxins with the CDC and must follow strict procedures for receipt, use, security and disposal. If you plan to use a Select Agent Toxin, contact the Biosafety Officer at EH&S.

Chemicals that are strongly implicated as a cause of cancer are termed carcinogenic. Substances defined by OSHA as select carcinogens fall into one of the categories listed below.

OSHA Carcinogen — a chemical regulated by OSHA as a carcinogen; each has its own standard in subpart 2 of the OSHA General Industry Standards.

Known Human Carcinogen — Classified as “known to be carcinogens”, in the most recent Annual Report on Carcinogens issued by the National Toxicology Program (NTP), or listed under Group 1 “carcinogenic to humans” by the International Agency for Research on Cancer (IARC.)

Potential Human Carcinogen — Listed under IARC Group 2A “probably carcinogenic to humans” or Group 2B “possibly carcinogenic to humans”, or classified as “reasonably anticipated to be a carcinogen” by NTP, and causes statistically significant tumor incidence in experimental animals under any of the following dosage criteria:

Inhalation exposure — chronic exposure (for a significant portion of a lifetime); 6-7 hours/day, 5 days/week; dose <10mg/m3.

Skin exposure — repeated skin exposure of <300mg/kg body weight per week.

Ingestion — daily dose <50mg/kg body weight.

Important: Remember that a chemical’s lack of inclusion in one of these lists does not necessarily imply that it is free from carcinogenic activity. Substances such as ethidium bromide that are used extensively in research do not have a substantial industrial use and, consequently, have not undergone a rigorous analysis for carcinogenicity. Although ethidium bromide is a well-known, potent mutagen it is not included in any of the lists. Laboratory staff are reminded to diligently research a chemical’s toxicity and hazard potential rather than relying exclusively on its presence in a list.

Reproductive toxins are chemicals that can cause problems with male and/or female reproduction. Adverse effects can include: reductions in libido, reduced fertility, embryo lethality, induction of chromosomal damage (mutations), malformations of the developing fetus (teratogenesis), and postnatal functional defects. Some chemicals cause problems for infants if a breast-feeding mother is exposed.

An allergy develops when the immune system reacts to a harmless substance as if it were infectious, triggering the production of antibodies. Subsequent exposures to even very small amounts of the same substance can trigger the allergic response. The individual who has developed an allergy can manifest the allergic response as a skin rash, eye irritation, allergic asthma, or, in severe allergic reactions, anaphylactic shock that can result in death if not treated quickly enough.

There are several chemicals and classes of chemicals that can be sensitizers. Examples of the more common sensitizer chemicals are: polyisocyanates, latex rubber, metals, formaldehyde, acid anhydrides, toluene, coal tar volatiles, and some phenol derivatives.

Prudent experimental planning requires not only an accurate assessment of the risks involved, but also selection of appropriate work practices. General laboratory safety practices and procedures are usually sufficient for operations involving hazardous chemicals of mild to moderate risk. When highly hazardous chemicals are involved, however, it may be necessary to take additional steps to adequately reduce risk and protect the health and safety of laboratory workers.

The goal in developing and implementing these special precautions is to set up multiple lines of defense to minimize the risks posed by highly hazardous chemicals. Consider each of the following provisions when developing special procedures for highly hazardous chemicals; some or all of them may apply, depending on the particular circumstances in which the substance will be used. In some circumstances only select precautions may be necessary, such as when the total amount of an acutely toxic substance to be handled is a small fraction of the harmful dose. In other circumstances it may be necessary to implement a full array of precautions.

The most effective way to minimize the risk posed by highly hazardous chemicals is to reduce or eliminate their use or to alter the procedure in a way that reduces the risk that they pose. Whenever possible replace highly hazardous materials with less hazardous substitutes. It is vital that lab staff examine every experiment utilizing highly hazardous chemicals to determine if these types of modifications can be implemented as a first step in risk reduction. Consult with supervisors, colleagues, and reference documents for assistance in identifying suitable substitutes and other risk reduction strategies.

When working with highly hazardous chemicals it is necessary to develop lab-specific written standard operating procedures (SOPs) relevant to safety and health considerations. The purpose of the SOP is to outline the risks associated with the highly hazardous chemicals in use as well as to describe the steps that lab staff will take to mitigate those risks. SOPs for highly hazardous chemicals can be substance specific or procedure specific, depending on the needs of a particular laboratory. See the Standard Operating Procedures page for guidance on developing a SOP for each highly hazardous chemical used in your laboratory.

Confine operations involving highly hazardous materials to a designated work area in the laboratory. This designated area can be the entire laboratory, an area of the laboratory, or a device such as a chemical fume hood. Isolate area from food and drink. Use warning signs to clearly indicate which areas are designated and the nature of the hazard. Use of designated areas need not be restricted to highly hazardous materials, as long as all lab staff are aware of the nature of the substances being used, and the special precautions, laboratory skill and safety discipline required to work in the area.

Limit access to laboratories where highly hazardous chemicals are in use to appropriately trained and authorized personnel. Depending on the materials and the circumstances of use, access control can be achieved by a combination of administrative procedures (such as prohibiting unauthorized visitors) and/or physical barriers (such as closing laboratory doors while highly hazardous chemicals are in use or storing highly toxic chemicals in locked cabinets).

Procedures involving highly toxic chemicals that can generate dust, vapors, or aerosols must be conducted in a hood, glove box, or other suitable containment device. These devices should be checked for acceptable operation prior to conducting experiments with highly hazardous chemicals. If experiments are to be ongoing over a significant period of time, frequent checks of hood function or the installation of a flow-sensing device with an audible or visual indicator of performance should be considered.

Experiments conducted with highly hazardous chemicals may need to be carried out in work areas designed to contain accidental releases. Hood trays and other types of secondary containers should be used to contain inadvertent spills, and careful technique must be observed to minimize the potential for spills and releases.

Equipment used for the handling of highly hazardous chemicals may need to be suitably isolated from the general laboratory environment. Decontamination of equipment should be properly performed when necessary, and should be conducted in a designated hood.

Wastes of acutely hazardous materials are generally on the EPA P-list, and care must be taken to not exceed the limits that can be accumulated at a satellite accumulation area. The limit for acutely hazardous waste at a satellite accumulation area is one quart (or quart-size) container. For proper disposal, follow the procedures outlined in the University’s Hazardous Chemical Waste Management Guidebook and on the Hazardous Chemical Waste web page.

An empty container that has held an acutely hazardous waste must be triple rinsed using a solvent (which might be water) capable of removing the acute hazardous waste prior to disposal of the container as regular trash. Each rinsing should be performed with an amount of solvent equal to approximately 5 percent of the volume of the container. The rinsate must be collected and disposed of as hazardous waste. The containers should be defaced of any chemical or hazardous waste labels prior to disposal as regular trash.

• Assure that the chemicals chosen are the least hazardous for the experiment being performed.
• Assure that individuals performing the work are properly trained, and know proper safety measures, including emergency procedures.
• Assure that the proper PPE and engineering controls are being utilized, and that the chemical is being handled and cleaned up properly.

• Be properly trained and familiar with the chemicals you will be working with. Ask questions if unclear, and obtain additional training whenever procedures or chemicals change.
• Be familiar with emergency procedures.
• Wear proper safety equipment. (safety glasses with side protection, goggles, gloves, etc.)
• Follow all proper methods for waste accumulation and disposal.

Provide consultative support, assist in managing unusual or special problems, dispose of wastes according to local and federal regulations when requested.