The hypophosphites do not appear to be currently used as ingredients in foods as indicated by a survey of the food industry conducted by a National Research Council subcommittee in 1970 and more recent information obtained from industry by the Select Committee. They had limited medical use many years ago in tonics and as therapeutic agents but appear to be no longer used for these purposes.
The acute toxicity of hypophosphites is relatively low; injected intraperitoneally in mice, the LD50 (30days) for the sodium salt was 1.6g per kg body weight. Calcium and sodium hypophosphites given orally or parenterally to experimental animals and man are rapidly excreted as hypophosphite in the urine. It is the opinion on the Select Committee that potassium hypophosphite is comparable to the sodium salt in excretion and toxicity.
Although animal feeding experiments indicate that the phosphorus in hypophosphites is not biologically available, no adverse effects were reported in young rats fed diets containing calcium hypophosphite (up to 4.3g per kg). Growth and calcium assimilation were as good as observed on diets containing salts recognized as good sources of calcium.
Although no reports were available on the biological effects of manganese hypophosphite, an evaluation of the health aspects of other manganous salts by the Select Committee has found no evidence that would indicate a hazard from manganous hypophosphite if used as a nutrient or dietary supplement.
In view of the foregoing the Select Committee concludes that: There is no evidence in the available information on manganous, calcium, potassium or sodium hypophosphite that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used in the manner now current or that might reasonably be expected in the future.