HAZARDOUS CHEMICALS                              

General:

Hazardous chemical means a chemical for which there is statistically significant evidence (based on at least one study conducted according to established scientific principles), that acute or chronic health effects may occur in exposed employees, or if it is listed in any of the following:

  •  
OSHA 29 CFR 1910.1000 Subpart Z
  •  
"Threshold Limit Values for Chemical Substances and Physical Agents in the Work Environment", ACGIH (latest edition)
  •  
"The Registry of Toxic Effects of Chemicals, NIOSH (latest edition)

In most cases, the label will indicate if the chemical is hazardous. Look for lay words like caution, hazardous, toxic, dangerous, corrosive, irritant, or carcinogen.

If you are not sure a chemical you are using is hazardous, review the Material Safety Data Sheet (MSDS) or contact your supervisor, instructor, or the EHRS Department.  

Types of Hazards:

Irritants are materials that cause inflammation of the body surface with which they come in contact.  The inflammation results from concentrations far below those needed to cause corrosion.  Examples of common irritants are:

 
ammonia
halogens
 
alkaline dusts and mists
nitrogen dioxide
 
hydrogen chloride
arsenic trichloride
 
ozone
hydrogen fluoride *
 
phosphorus chloride
phosgene *

* These materials also have other hazardous properties.

Irritants can also cause changes in the mechanics of respiration and lung function.   Some examples include:

 
sulfur dioxide
formaldehyde *
 
acetic acid
sulfuric acid
 
formic acid
halogens
 
acrolein    

* These materials also have other hazardous properties.

Long term exposure to irritants can result in increased mucous secretions and chronic bronchitis.

A primary irritant exerts no systemic toxic action, either because the products formed on the tissue of the respiratory tract are non-toxic or because the irritant action is more severe than a systemic toxic action.  Example:  hydrogen chloride.

A secondary irritant's effect on mucous membranes is overshadowed by a systemic effect resulting from absorption.  These include:

  •  
hydrogen sulfide
  •  
aromatic hydrocarbons

Exposure to a secondary irritant can result in pulmonary edema, hemorrhage and tissue necrosis.

Simple Asphyxiants deprive the tissue of oxygen.  Simple asphyxiants are inert gases that displace oxygen.  These include:

  •  
nitrogen
  •  
nitrous oxide
  •  
carbon dioxide
  •  
helium

Chemical asphyxiants render the body incapable of maintaining an adequate oxygen supply.  They are active at very low concentrations (few ppm's).   These include:

  •  
carbon monoxide
  •  
cyanides

Primary anesthetics have a depressant effect upon the central nervous system, particularly the brain.  These include:

  •  
halogenated hydrocarbons
  •  
alcohols

Hepatotoxic agents cause damage to the liver.  These include:

  •  
carbon tetrachloride
  •  
tetrachloroethane
  •  
nitrosamines

Nephrotoxic agents damage the kidneys.  These include:

  •  
halogenated hydrocarbons
  •  
uranium compounds

Neurotoxic agents damage the nervous system.  The nervous system is especially sensitive to organometallic compounds and certain sulfide compounds.  These include:

triakyl tin compounds
  •  
tetraethyl lead
  •  
methyl mercury
  •  
carbon disulfide
  •  
organic phosphorus insecticides
  •  
manganese
  •  
thallium

Some toxic agents act on the blood or hematopoietic system.   The blood cells can be directly affected or the bone marrow can be damaged.   These include:

  •  
nitrites
  •  
aniline
  •  
toluidine
  •  
nitrobenzene
  •  
benzene

There are toxic agents that produce damage of the pulmonary tissue (lungs) but not by immediate irritant action.  Fibrotic changes can be caused by free silica and asbestos.  Other dusts can cause a restrictive disease called pneumoconiosis.

A carcinogen commonly describes any agent that can initiate or speed the development of malignant or potentially malignant tumors, malignant neoplastic proliferation of cells, or cells that possess such material.  See listing of some carcinogenic materials in the Appendix.  Examples of some carcinogens commonly used are:

  •  
chloroform
  •  
benzene
  •  
formaldehyde
  •  
carbon tetrachloride
ethylene amine

Select carcinogen means any substance that 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 National Toxicology Program (NTP), "Annual Report of Carcinogens: (latest edition).
  •  
It is listed under Group 1, "carcinogenic to humans" by the International Agency for Research on Cancer Monographs (IARC).
  •  
It is listed under 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 according to any of the following criteria:
a. After inhalation exposure of 6 - 7 hours per day, 5 days per week, for a significant portion of lifetime, to doses of less than 10mg/m3.
b. After repeated skin application of 300 mg/kg of body weight per week.
c. After oral doses of less than 50 mg/kg of body weight per day.

Link to the International Agency for Research on Cancer.

Reproductive hazard means chemicals that affect the reproductive capabilities including chromosomal damage (mutagens) and effects on the fetus (teratogens).  See list of some reproductive hazards in the Appendix.

A mutagen affects the chromosome chains of exposed cells.   The effect is hereditary and becomes part of the genetic pool passed onto future generations.

A teratogen (embryotoxic or fetotoxic agent) is an agent that interferes with normal embryonic development without damage to the mother or lethal effect on the fetus.  Effects are not hereditary.

A sensitizer causes a majority of the exposed population to develop an allergic reaction in normal tissue after repeated exposure to the chemical.   The reaction may be as mild as a rash (contact dermatitis) or as serious as anaphylactic shock.

Acutely toxic chemicals are substances falling into the following categories:

  •  
A chemical that has a median lethal dose (LD50) of 50 milligrams or less per kilogram of body weight, when administered to albino rats weighing 200g to 300g each.
  •  
A chemical that has a median lethal dose (LD50) of 2000 milligrams or less per kilogram of body weight, when administered by continuous contact for 24 hours, (or less if death occurs within 24 hours), to the bare skin of albino rats weighing 200g to 300g each.
  •  
A chemical that has a median lethal concentration (LC50) in air of 200 parts per million by volume, or less, of gas, or vapor, or 2 milligrams per liter or less, of mist, fume, or dust, when administered by continuous inhalation for one hour, (or less if death occurs within one hour), to albino rats weighing 200g to 300g each.

Extremely toxic chemicals are substances that cause irreversible neurological damage or death with extremely small doses. Substances in this class include many organic mercury compounds such as dimethyl mercury and MPTP (1-methyl-4phenyl-1,2,3,6-tetrahydropyridine) which can cause irreversible Parkinsonian syndrome. Lab work with these materials requires review by EHRS and typically includes chemical resistant gloves and protective clothing.

See list of acutely toxic chemicals in the Appendix.


University of the Sciences in Philadelphia • 600 South Forty-third Street • Philadelphia, PA 19104-4495 • phone: 215-596-8800 • email: safety@usp.edu