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SAN JOAQUIN DELTA COLLEGE <br /> THRESHOLD LIMIT VALUES <br /> Toxicity ppm mgW nippcf <br /> Slight over 500 over 0 5 50 <br /> Moderate 101-500 0 101-05 20 <br /> High 0-100 0-01 Z <br /> TABLE M <br /> Threshold Limit Value - Short Term Exposure Limit (TLV-STEL) - The Concentration to which workers can be exposed <br /> continuously for a short period of tune without suffering from 1) irritation, 2) chronic or irreversible tissue damage, or 3) <br /> narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work <br /> efficiency, and provided that the daily TLV-TWA is not exceeded It is not a separate independent exposure limit, rather it <br /> supplements the time-weighted average (TWA) limit where there are recognized acute effects from a substance whose toxic <br /> effects are primarily of a chronic nature STEL's are recommended only where toxic effects have been reported from high <br /> short-term exposures in either humans or animals <br /> The TLV's for gases and vapors are expressed in parts per million (ppm) which stands for parts of gases or vapors per <br /> million parts of air The TLV's for fumes, mists, and some dusts are given as milligrams per cubic meter (mg/m') <br /> The TLV's of some dusts, i e, silica and asbestos, are expressed in millions of particles per cubic foot of air(mppeo <br /> A STEL is defined as a 15-minute tune-weighted average exposure which should not be exceeded at any time during a work <br /> day even if the eight hour time-weighted average is within the TLV Exposures at the STEL should not be longer than 15 <br /> minutes and should not be repeated more than four times per day There should be at least sixty minutes between successive <br /> exposures at the STEL <br /> Threshold Limit Value- Ceiling(TLV-C) - The concentration that should not be exceeded during any part of the working <br /> exposure <br /> Toxicology is the science of poisons, their effects on the body, various antidotes for their action, and their detection in body <br /> fluids and tissues See Table IV for descriptive notations Since all chemicals can be toxic, it is necessary to define the <br /> conditions of an exposure as well as the amount of chemical involved in an exposure to compare toxicities(see Table V) <br /> NOTATIONS DESCRIPTIVE OF THE TOXICOLOGY <br /> Abbreviation Definition not limited to effects listed <br /> ALR Allergic systemic reaction such as might be experienced by individuals sensitized to penicillin <br /> BCM Blood clotting mechanism effects-any effect which increases or decreases clotting time <br /> BLD Blood effects - effect pm all b elements, electrolytes, pH, protein, oxygen carrying or releasing <br /> capacity <br /> BFR Blood pressure effects - any effect which mcre-ases or decreases any aspect of blood pressure <br /> TABLE N <br /> Page #4 <br />