Chapter 2: Other surfactants · Part 4: Soap
Sodium tallowate
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The worst fact: swallowing bar soap can be serious for people with dementia. Of 553 cases reported to one French poison centre (2000–2015), two people died, both with dementia: one of aspiration pneumonia, one of cardiogenic shock after throat swelling, vomiting and airway obstruction.
Why brands use it: it's the sodium salt of tallow fatty acids, mainly C14 to C18 chains.
Take care if: someone with dementia lives with you; keep bar soap out of reach.
Comes from: tallow (animal fat) boiled with caustic soda.
Myth check: "Tallow soap can carry mad cow disease": the US FDA rules that tallow derivatives made by saponification are not "prohibited cattle material", and its advisers found the manufacturing conditions "sufficient to further reduce the BSE risk".
Contaminants: nil. (Badly made soap can carry leftover caustic soda: "soaps with an appreciable content of free alkali (eg some laundry soaps) are less benign".)
Fair to say: soap is readily biodegradable, and swallowed laundry products containing soap aren't expected to cause "any significant adverse health effect".
Correct as of November 2026. What the badges mean
Sources
- US FDA. Consumer antiseptic wash final rule (2016); Antibacterial soap consumer update; Use of materials derived from cattle in human food and cosmetics, final rule (2016).
- De Pralormo S et al. Bar soap ingestion, Angers Poison Control Centre. Clin Toxicol 2019, PMID 30307335.
The full source list is at the end of Chapter 2.