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Extremely Hazardous Substances

The Lab Standard requires that work with extremely hazardous chemicals be done in a designated area. Chemicals for which special precautions are to be taken include carcinogens, reproductive toxins and certain chemicals with a high degree of acute toxicity. Hazardous substances are listed in Appendices H and I.


"Select carcinogens" are defined by the Lab Standard as being any substance which meets one of the following criteria:

  • It is regulated by OSHA as a carcinogen.
  • It is listed under the category "known to be carcinogens" in the Annual Report on Carcinogens published by the National Toxicology Program (NTP) (latest edition).
  • It is listed under Group 1 ('carcinogenic to humans') by the International Agency for Research on Cancer Monographs (IARC) (latest edition).
  • It is listed in either Group 2A or 2B by IARC or under the category, reasonably anticipated to be carcinogens by NTP, and causes statistically significant tumor incidence in experimental animals in accordance with any of the following criteria:
    • After inhalation exposure of 6-7 hours per day, 5 days per week, for a significant portion of a lifetime to dosages of less than 10 mg/m3.
    • After repeated skin application of less than 300 (mg/kg of body weight) per week.
    • After oral dosages of less than 50 mg/kg of body weight per day.

A list of materials which fall into these categories can be found here as well as in Appendix H.

Reproductive Toxins

Reproductive hazards are defined by the Lab Standard as:

"toxins (which) may manifest themselves in lethal effects on the fertilized egg, developing embryo or fetus or teratogenic (malformation) effects in the fetus. In addition, certain reproductive toxins may cause infertility in males and females."

Examples of reproductive toxins include: benzene, mercury, ethylene dibromide, carbon monoxide, anesthetic gases (halothane, methoxyflurane), ionizing radiation, ethylene oxide, ethylene thiourea, glycidyl ethers, lead and 1,2-dibromo-3-chloropropane.

A list of hazardous substances can be found here.

Acute Toxins

The Lab Standard defines "Substances with high acute toxicity such as hydrogen cyanide, hydrogen sulfide and nitrogen dioxide are included under the category of substances for which employers must consider the need for special precautions. Such substances may be fatal or cause damage to target organs as a result of a single exposure or exposures of short duration."

A list of acute toxins can be found here.

Procedures for Working with Hazardous Substances

Work with these chemicals should be performed within a functioning fume hood, biological safety cabinet, ventilated glove box, sealed system, or other system designed to minimize exposure to these substances. (The exhaust air from the ventilation systems may require scrubbing before being released into the atmosphere.) In all cases, work with these types of chemicals shall be done in such a manner that the permissible exposure limits or similar standards are not exceeded.

  • Compressed gas cylinders which contain acutely toxic chemicals such as arsine and nitrogen dioxide should (and may be required to) be kept in ventilated gas cabinets.
  • The ventilation efficiency of the designated fume hood, glove box or gas cabinets, and the operational effectiveness of mechanical and electrical equipment used to contain or manipulate these special substances should be evaluated periodically.
  • Gloves and other appropriate protective apparel must be worn.
  • Unless marked for "Work in Progress" (not to exceed one week) with approximate levels of hazard, the work area shall be decontaminated upon departure from the laboratory.
  • Laboratory workers of child-bearing age should be especially cautious when working with reproductive toxins.

Each laboratory utilizing hazardous substances must designate an area for this purpose and must sign or mark this area with an appropriate hazard warning. The designated area may be an entire laboratory, an area of the laboratory or a device such as a fume hood or glove box. The designated area should be marked with "DANGER, specific agent, AUTHORIZED PERSONNEL ONLY" or a comparable warning sign.

The materials on this list require prior approval prior to acquisition and purchase:

  • cyanide compounds
  • sulfide compounds
  • Picric acid
  • sodium picrate
  • chlorinated dibenzo compounds
  • depleted source material