Inositol phosphates

Endpoint summary

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Additional information

‚Inositol phosphates‘ is mainly constituted by various phosphorylated derivatives of inositol (IPn) and orthophosphoric acid. Information on these constituents is presented below.

Phosphorylated derivatives of inositol (IPn)

IPnare a group of mono- to poly-phosphorylatedinositols(IP1 to IP6). In nature, they are found in most legume seeds and cereal grains where they play a role in phosphorus storage. In much smaller amounts, IP6 and the lower phosphorylated forms are contained in most mammalian cells where they are important in regulating vital cellular functions such as calcium flow in cells, cell growth, apoptosis, cell migration, endocytosis and cell differentiation (Shamsuddin, 1995; Zhou and Erdman, 1995; Farghalyet al., 2010). IP1 – IP4 are recognized as intracellular messengers (Shamsuddin, 1995). IP6, also known as ‘phytic acid’ or phytate in its salt form, has been extensively studied due to its anti-cancer properties. Testing in animals has shown anti-neoplastic properties in breast, colon, liver, leukemia, prostate, sarcomas and skin cancer (Fox and Eberl, 2002).

IPn, in particular IP6, have the ability to chelate multivalent ions, especially zinc, calcium and iron. This confers to IPn negative as well as positive nutritional and environmental properties, and makes them interesting for both medical and industrial applications (Oatway et al., 2001).

IPn are taken up by humans and animals via the diet. Studies in rat demonstrate that IP6 is quickly absorbed from the stomach and upper intestine, then distributed as inositol and IP1. When in salt form however, intestinal absorption is low, leading to poor bioavailability of some minerals (Zhou and Erdman, 1995).

Orthophosphoric acid (OP)

Phosphoric acid is an essential constituent of the human organism, not only in the bones and teeth, but also in many enzyme systems. Phosphorus plays an important role in carbohydrate, fat and protein metabolism.

OP is absorbed from, and to a limited extent secreted into, the gastrointestinal tract. Transport of phosphate from the gut lumen is an active, energy-dependent process that is modified by several factors. Vitamin D stimulates phosphate absorption, an effect reported to precede its action on calcium ion transport. In adults, about two thirds of the ingested phosphate is absorbed, and almost entirely excreted into the urine. In growing children, phosphate balance is positive. Concentrations of phosphate in plasma are higher in children than in adults. This "hyperphosphatemia" decreases the affinity of hemoglobin for oxygen and is hypothesized to explain the physiological "anemia" of childhood (Hardmanet al., 1996).

Additional information

No information could be found on dermal or respiratory absorption of ‘inositol phosphates’. However, because the substance is corrosive to skin and eyes, damage to the tissue surfaces may enhance penetration, as described in REACH Guidance R.7.C, Table R.7.12-3.