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Description of key information

According to the REACH Guidance IR CSA R.7c, an assessment on the toxicokinetic properties of the substace has been performed, resulting in low absorption via de oral and dermal route, while via the inhalation route no potential inhalable fraction is present due to the high particle size.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
10
Absorption rate - dermal (%):
10

Additional information

In general, a compound needs to be dissolved before it can be taken up from the gastro-intestinal tract after oral administration. Therefore, the good water solubility favors the uptake from the gastro-intestinal tract. However, the presence of ionisable groups and the moderate high molecular weight are indicative for impaired absorption, as ionized substances do not easily pass the gastro-intestinal wall. It is therefore unlikely that sodium ferrocyanide will show a high systemic exposure after oral administration. Based on the available physical/chemical properties of sodium ferrocyanide, for risk assessment purposes the oral absorption is set at 10%. The results of the toxicity studies do not provide reasons to deviate from this proposed oral absorption factor.

Excretion of sodium ferrocyanide occurs mainly via urine through glomerular filtration. Bioaccumulation is not expected for this substance, as during metabolism cyanide will be transformed to thiocyanide, which has a plasma half-life of less than 1 hour.

In humans, particles with aerodynamic diameters below 100 µm have the potential to be inhaled. Based on the particle size of sodium ferrocyanide, particles <100µm which have the potential to be inhaled, are not present.

According to the criteria given in the REACH Guidance, 10% dermal absorption will be considered in case MW>500 and log Pow <-1 or >4, otherwise 100% dermal absorption should be used. As the physical/chemical properties of sodium ferrocyanide do not meet the criteria for limited dermal absorption, for risk assessment purposes 100% dermal absorption needs to be considered. It is, however, generally accepted that dermal absorption is lower compared to oral absorption. The 100% dermal absorption derived from the physical/chemical properties of the substance should therefore be considered as unrealistic worst case assumption. For risk assessment purposes a lower dermal absorption value of 10% is considered more appropriate.