Namely
Sodium hydroxymethylglycinate is used as a preservative in cosmetics as an alternative to parabens. It acts on its own on a fairly broad spectrum of microbes and bacteria of all kinds. Nevertheless, some studies show that it can release formaldehyde (known carcinogen, irritant and allergen) under certain conditions which, let's face it, seem infrequent. Moreover, when this is the case, the quantities released are negligible. However, considering that it is possible to do otherwise, we classify this ingredient in red on Inci Beauty. The ingredient is reputed to be very irritating to the skin and eyes, and seems to give off a very strong rancid odor even below the concentrations authorized by Europe. This leads manufacturers to dilute it too much and therefore reduce its preservative effect or to use too many masking agents.