3.5.1 General Information
Substances that possess the characteristic of high acute toxicity can cause damage after a single or short-term exposure. The immediate toxic effects to human health range from irritation to illness and death. Hydrogen cyanide, phosgene, and nitrogen dioxide are examples of substances with high acute toxicity. The lethal oral dose (LD50) for an average human adult for highly toxic substances range from one ounce to a few drops. The following procedures should be used when the oral LD50 of a substance in the rat or mouse is less than 50 milligrams per kilogram body weight for solid materials or non-volatile liquids and 500 mg/kg body weight for volatile liquids or gases. Oral LD50 data for the rat or mouse is listed in the substance’s SDS. The LD50 toxicity test is usually the first toxicological test performed and is a good indicator of a substances acute toxicity.
Substances that possess the characteristic of high chronic toxicity cause damage after repeated exposure or exposure over long periods of time. Health effects often do not become evident until after a long latency period – twenty to thirty years. Substances that are of high chronic toxicity may be toxic to specific organ systems – hepatotoxins, nephrotoxins, neurotoxins, toxic agents to the hematopoietic system and pulmonary tissue or carcinogens, reproductive toxins, mutagens, teratogens or sensitizers. The definition of each of these categories of toxic substances and examples of substances, which fall into each of these different categories, can be found in Section 4.1 of this manual.
Specific acute and chronic toxicity information on the substances used in your laboratory can be found on these substances’s SDS. See Section 1.5.2 for information on how to obtain/locate SDSs. If you have additional questions contact the Chemical Hygiene Officer.
3.5.2 Special Handling Procedures
Avoid or minimize contact with these chemicals by any route of exposure. Protect the hands and forearms by wearing gloves and laboratory coat. Rinse gloves prior to removing them.
Use these chemicals in a chemical fume hood or other appropriate containment device if the material is volatile or the procedure may generate aerosols (See guidelines for chemical fume hood use in Section 2.3.5.1). If a chemical fume hood is used it should be evaluated to confirm that it is performing adequately (a face velocity of at least 100 linear feet per minute (+20%)) with the sash at the operating height.
Store volatile chemicals of high acute or chronic toxicity in the cabinet under the hood or other vented area. Volatile chemicals should be stored in unbreakable primary or secondary containers or placed in chemically resistant trays (to contain spills). Nonvolatile chemicals should be stored in cabinets or in drawers. Do not store these chemicals on open shelves or counters.
Decontaminate working surfaces with wet paper towels after completing procedures. Place the towels in plastic bags and secure. Dispose of them in the normal trash.
Volatile chemicals should be transported between laboratories in durable outer containers.
Vacuum pumps used in procedures should be protected from contamination with scrubbers or filters.
If one or more of these substances are used in large quantities, on a regular basis (three or more separate handling sessions per week), or for long periods of time (4-6 hours) a qualitative and potentially quantitative exposure assessment should be performed. Contact the Chemical Hygiene Officer to perform this assessment.
Lab personnel of childbearing age should be informed of any known male and female reproductive toxins used in the laboratory. An employee who is pregnant, or planning to become pregnant and who is working with potential reproductive toxins that might affect the fetus, should contact the Chemical Hygiene Officer to evaluate their exposure and inform her personal physician. The Chemical Hygiene Officer can assess potential exposures and work with the employee and laboratory supervisor, if necessary, to adjust work practices to minimize the potential risk.