In general, "toxicity" is measured through the use of 8- and 12-hour "time-weighted average exposure limits" (AEL). Similar terms you might find on labels and MSDS sheets include "Average Exposure Limits" (AEL),"Personal Exposure Limits" (PEL) and "Threshold Exposure Limits" (TEL). One special group are the "Threshold Limit Values" (TLVs) which only are established by the American Conference of Governmental Industrial Hygienists (ACGIH). While there are some technical differences between the terms, the general intent is identical: to quantify the relative safety of a chemical product. There are also exposure limits for shorter time periods and even "instantaneous" exposure limits which further quantify the risk of using a specific chemical.

As a bit of background, the "8-hour time-weighted exposure limit" is estimated to be one-tenth the minimum airborne concentration of vapors to which workers may be repeatedly exposed for an eight-hour workday over a hypothetical thirty-year career without suffering any possible health effects. All exposure limits are expressed in "parts per million" (p.p.m.). For example, about 18% of the air we breathe is pure oxygen. This means that oxygen is present in the atmosphere at 180,000 parts per million.

After numerous toxicity studies DuPont has established for Vertrel^® XF (the basic Vertrel^® product) an Acceptable Exposure Limit (AEL) of 200 ppm for an 8- and 12-hr "time-weighted average" (TWA). The AEL for HFC-365 has been set at 1,000 ppm. Other blends have similar or higher values. This is about normal for modern industrial chemicals; some are lower, a few are higher, but 200 ppm is a modest and prudent safety level. Special note: typical inhalation exposures while working around a vapor degreaser are normally less than 50 ppm.

Also, after further testing, an instantaneous ceiling limit of 400 ppm has been set by DuPont for all of the Vertrel^® products. A ceiling limit is the airborne concentration that should not be exceeded during any part of the working day.

In comparison, the represent airborne concentrations to which nearly all workers may be repeatedly exposed without adverse effect. The 8-hr PEL values for the most common components in the most popular Vertrel^® blends are:

The DuPont exposure limit for each Vertrel^® blend is shown on the MSDS Sheet for each product. Contrast these exposure limits with those of other cleaners on the market today:

Clearly, Vertrel^® is a modern and safe product which can be safely used in commercial applications without fear of harm to employees and technicians.

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