Many companies use aerosol degreasers containing a liquid called “normal propyl bromide” (nPB). Normal propyl bromide is an organic industrial solvent used in a wide variety of applications such as fire retardants, water purification, pesticides and drugs. In general, this is a great product: nonflammable, fast-drying, highly aggressive, cleans great and very affordable. But it carries serious toxicity worries. The original toxicity level (called a “TLV”, “AEL” or “PEL” by different companies) was set at 100 ppm and at that level, nPB could be safely used in aerosols. However, newer studies found nPB damages the nervous system, alters human DNA, impairs fertility and there is a risk of cancer. Based on these reports, in 2014 a safety organization called ACGIH lowered the exposure rating to 0.1 ppm. It is impossible to use nPB in an aerosol and stay below this recommended safety level. Today, new cleaning chemicals are available which work as well and are far safer.