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3. Effects of Chronic Exposure to Product: This refers to overexposure to a controlled
product over a long period of time -- with symptoms that develop over a long period of
time. Asbestos, described above, is an example of a product causing chronic effects.

4. Exposure Limits: These are the maximum limits of exposure by inhalation of
airborne substances (e.g. dusts, vapours, fumes, etc.) which workers may be exposed
to during their shift. They are set to prevent adverse health effects in the average
healthy adult; some workers may be more sensitive and require additional protection.
The most commonly quoted exposure limits are Threshold Limit Values (TLVs). These
are guidelines developed by a professional association in the United States. There are
3 main types of TLVs:

1) TWA - Time Weighted Average: The average allowed exposure over a normal
8-hour day or 40-hour week.

2) STEL - Short-Term Exposure Limit: The maximum concentration to which
workers can be periodically exposed for a period of up to 15 minutes. (Even with
these STELs the average exposure for the day cannot exceed the TWA.)

3) C – Ceiling: The highest allowed exposure at any time. (Even with a Ceiling,
the average for the day cannot exceed the TWA.)

In Alberta, Occupational Exposure Limits (OELs) have been established in the OHS
Code (Part 4). The OELs are legal limits in Alberta. In most cases, the limits are the
same as TLVs. But sometimes the OELs are lower; other times the TLVs are lower.
Because the MSDS probably won’t quote Alberta’s OELs, you should check the OHS
Code to see if the OELs are different than the limits listed.

5. Irritancy of Product: Irritancy describes the nature (e.g. itching, burning, reddening,
etc.) of effects to the eyes or skin. It may also describe severity in general terms (e.g.
mild, moderate, or severe). Knowing the irritant properties can help determine handling
and personal protective equipment needs.

6. Sensitizing Capability of Product: A sensitizer is a substance which on first exposure
causes little or no response, but which after repeated exposure can cause a significant
marked reaction. The reaction is not related to the levels of exposure, and may not
necessarily be limited to the contact site. Although skin sensitization is most common,
respiratory sensitization is also known. Formaldehyde can cause skin and respiratory
sensitization; isocyanates are serious respiratory sensitizers. Sensitized individuals can
develop a life threatening reaction to a low dose to exposures (below the OEL).

7. Carcinogenicity (Cancer-Causing): This sub-section describes cancer-causing
properties of the product. You will see such phrases as “Recognized Carcinogen”,
“Probably Carcinogenic”, “Suspect Carcinogen” in this sub-section.

8. Teratogenicity and Embryotoxicity (Effects to the Fetus): Exposure of a pregnant
worker to teratogens or embryotoxins can be dangerous to her unborn child at levels
which cause no effects to her. Injuries can include death, malformation, growth
retardation, and others. Thalidomide and alcohol are examples.

9. Reproductive Toxicity: Causes sterility or has an adverse effect on reproductive
capability following exposure

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