In order to clarify the definitions used in OSHA's Health and Safety Regulations, requiring prior approvals for toxic compounds and carcinogens, the following list of definitions has been derived directly from "Health Hazard Definitions", OSHA Hazard Communication Standard, 29 CFR 1910.1200 - Appendix A.
- CARCINOGEN: A chemical is considered to be a carcinogen if:
- IARC evaluation has found the chemical to be a carcinogen or potential carcinogen. (IARC is the International Agency for Research on Cancer).
- It is listed in the "Annual Report on Carcinogens" prepared by the National Toxicity Program. See EHP and ATSDR
- CORROSIVE: A chemical that causes visible destruction of, or irreversible alterations in living tissue by chemical action at the site of contact.
- HIGHLY TOXIC: A chemical falling within any of the following descriptions:
- Has an LD50 of < 50 milligrams (mg)/kg body weight orally, in albino rats weighing 200 - 300 grams.
- Has an LC50, of < 200 parts per million by volume with air, continuous inhalation for one hour, in 200 - 300gm albino rats.
- IRRITANT: A chemical which is not corrosive, but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact.
- TOXIC: A chemical falling within any of the following descriptions:
- Has an LD50 of 50 mg < x < 500 mg/kg body weight orally in albino rats of 200 - 300 grams body weight.
- Has an LD50 of 200 mg < x < 1,000 mg/kg body weight, when administered continuously for 24 hours on bare skin of albino rabbits of 2-3 kilograms weight.
- Has an LC50 of 200 ppm < X < 2,000 ppm of gas or vapor in air, for one hour exposure by continuous inhalation to albino rats, 200- 300 grams body weight.
This information should appear on the Material Safety Data Sheets provided to you by the manufacturer, vendor or supplier of the chemical. The best information is Human exposure LD50's and LC50's. When only animal data is presently available, use the information provided above to make comparison for toxicity determination.
When this information does not appear, other sources can be used to help determine if a chemical falls into a "Prior Approval" classification. The NFPA Diamond sign has a "Health" category entry which can range from "0" to "4". The following values and definitions are assigned to these designations: (from "National Fire Protection Association", Code #704).
CATEGORY "4": Materials that under emergency conditions are lethal:
- Gases with an acute inhalation toxicity LC50 of < 1000ppm
- Liquids that have a saturated vapor concentration at 68oF ten times greater than the LC50 for acute inhalation, and the LC50 is <1000ppm. [For these liquids, the vapor concentration would be vp / 760mm = 106 = ppm; vp = vapor pressure, at 68oF]
- LD50 for acute dermal toxicity is < 40mg/kg.
- LD50 for acute oral toxicity is < 5 mg/kg.
CATEGORY "3": Materials that, under emergency conditions can cause serious or permanent injury;
- Gases with an acute inhalation toxicity LC50 of between
1000< x < 3000 ppm.
- Liquids that have a saturated vapor concentration at 68o F equal to or greater than the LC50 for acute inhalation toxicity, and the LC50 is < 3000ppm, and does not meet the criteria degree for hazard Category "4". (above)
- Materials corrosive to the respiratory tract.
- Materials that are corrosive to the eye or cause irreversible corneal opacity.
- Materials that are severely irritating or corrosive to skin.
- The LD50 is 5 mg/kg < x < 50 mg/kg.
Any chemical having a CATEGORY "3" or "4" Health designation should be treated as a "Prior Approval" material and regarded as ranging from moderate to highly toxic.
The OSHA 29 CFR 1910-Subpart Z "Air Contaminants List" gives values as permissible exposure levels for an 8-hour period. The values are given as part per million values and as mg/M3 values. A quick determination of Relative Toxicity can be made using these values. Chemicals with "PEL's or TLV's
(Threshold Limit values) of between 100 - 1000ppm are relatively safe and are ranged from "Moderately" to "Slightly" toxic. It is still good practice to limit exposure to these chemicals, since there may be chronic toxic effects on long -term exposure.
Chemicals with PEL's or TLV's of less than 100ppm are beginning to range down into "Highly" and "Extremely" toxic with each change in order of magnitude, i.e.: 10ppm, 1ppm, 0.1ppm etc.
In conclusion, any chemical with a "3" or "4" Health designation on an NFPA Diamond sign, or HMIS sign, or with LD50 values as described above, or with anLD50 of< 500 mg/kg Human, or a PEL (TLV) of < 100ppm should be considered as a Prior Approval Material, and regarded as having sufficient toxic properties to warrant special storage, handling and disposal practices.
Any activities involving these chemicals should be reported to the MSMC Safety Officer, ext.47233, and/ or the MSSM Biosafety Officer, ext.45169 PRIOR to obtaining or using the chemicals. If special respiratory protection, gloves, protective clothing are required for handling these chemicals, they must be purchased beforehand, and fit-testing and proper use training arranged and provided to all personnel who will use this equipment.