The Dirty Truth About Industrial Grade Lye

Part 5

What ARE Those Contaminants, Exactly?

We mentioned heavy metals. Let's not let them hide behind the vague term "impurities."

Lead (Pb):

One of the most documented contaminants in industrial-process chemicals. Once absorbed, lead is taken up in the blood and deposited in soft tissues including the brain, liver, kidney, and bone marrow. There is no known safe level of lead exposure. Chronic low-level exposure — exactly the kind that comes from repeated skin contact over months and years — is associated with neurological damage, cognitive impairment, kidney dysfunction, and reproductive harm.

Mercury (Hg):

A documented concern in lye produced via the Mercury Cell Process. Mercury is notorious for its ability to cross the blood-brain barrier. Chronic mercury exposure can produce tremors, memory loss, mood changes, muscle weakness, kidney failure, and peripheral neuropathy. Even the Cosmetic Ingredient Review Expert Panel's Certificate of Analysis for some food-grade lye suppliers still lists mercury at up to 100 ppm — underscoring that any relaxation of food-grade standards in industrial-grade lye compounds this risk significantly.

Nickel and Copper:

Both documented in industrial-grade NaOH and both recognized as skin sensitizers and allergens at elevated exposures. Nickel exposure is among the most common causes of allergic contact dermatitis worldwide.

Iron (Fe):

Present in industrial-grade NaOH and, while not acutely toxic at trace levels, can catalyze oxidative reactions in skin cells.

Chlorides:

Industrial-grade lye produced via the diaphragm process contains significantly higher chloride content than membrane or food-grade product. Elevated chlorides can increase corrosivity and interfere with the saponification process in ways that leave more reactive compounds in the finished bar.

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