An Introduction to Chemical Hazards in the Workplace
” … What makes a chemical toxic?

“The toxicity of a substance is its ability to cause harmful effects. These
effects can strike a single cell, a group of cells, an organ system, or the
entire body. A toxic effect may be visible damage, or a decrease in
performance or function measureable only by a test. All chemicals
can cause harm. When only a very large amount of the chemical can
cause damage, the chemical is considered to be relatively non-toxic.
When a small amount can be harmful, the chemical is considered toxic.

“The toxicity of a substance depends on three factors: its chemical structure,
the extent to which the substance is absorbed by the body, and the body’s
ability to detoxify the substance (change it into less toxic substances) and
eliminate it from the body.

“Are “toxic” and “hazardous” the same? “No. …”
http://www.dhs.ca.gov/ohb/HESIS/uts.htm?

California’s Occupational Health Branch (OHB)
http://www.dhs.ca.gov/ohb/Default.htm