Phosphorus

Endpoint summary

Description of key information

No bioaccessibility of elemental Red Phosphorus (for details please refer to Chapter 7.1). Bioaccessibility of the dissolved oxidized Phosphorus species (Hypophosphite, Phosphohite and Phosphate) was determined to be 1.3 +/- 0.4 % of the applied Red Phosphorus amount.

Additional information

Please refer to "Justification for classification or non-classification"

Justification for classification or non-classification

In an absorption study conducted using the artificial gastro-intestinal TIM model (please refer to Chapter 7.1.1) it was clearly demonstrated that elemental Red Phosphorus is systemically not available after oral uptake. Only the oxidizedPOspecies (Hypophosphite, Phosphite, or Phosphate) were found in the dialysate which represents the uptaken fraction of applied substances. The bioaccessibility of Red Phosphorus under the conditions of a fasted human adult was determined to be 1.3 ± 0.4 % (as oxidized species) of the whole application amount.

Taking into account that the mean food consumption of a rat is 100 g/kg bw/d and a rhodent standard diet contains 0.7‑0.8 % Phosphorus, the mean daily Phosphorus uptake is calculated to be 0.8 g/kg bw/d:

 

Mean food consumption (rat): 100 g/kg bw/d

Mean phosphorus content in rhodent diet: 0.8 %

 

=> (0.8 % x 100 g/kg bw/d) / 100 % =0.8 g Phosphorus/kg bw/d

 

According to the results of the TIM (bioaccessibility) study 1.3 ± 0.4 % of the applied amount of Red Phosphorus is bioaccessible as oxidized water-soluble species (Hypophosphite, Phosphite, and Phosphate). Due to the current OECD Guidelines for testing of chemicals the limit dose for repeated dose studies is 1000 mg/kg bw/d. Application of 1000 mg Red Phosphorus/kg bw/d leads to a bioaccessible amount of 13 mgPOspecies/kg bw/d:

 

Limit dose: 1000 mg Red Phosphorus/kg bw/d

Bioaccessibility of Red Phosphorus (result from TIM study): 1.3 ± 0.4 %

 

=> (1.3 % x 1000 mg/kg bw/d) / 100 % =13 oxidized Phosphorus species/kg bw/d

 

Therefore, applying the results of the TIM study (1.3 % bioaccessibility of Red Phosphorus) and the assumed daily limit dose of 1000 mg/kg bw/d 13 mgPOspecies/kg bw/d are available systemically under worst case conditions.

 

Phosphorus uptake via rhodent diet: 800 mg/kg bw/d

Bioaccessible Phosphorus from limit dose: 13 mg/kg bw/d

 

=> (13 mg/kg bw/d x 100%) / 800 mg/kg bw/d = 1.6 %

 

Compared to the daily uptake of 800 mg Phosphorus/kg bw/d via diet this additional amount of oxidized Phosphorus species (1.6 % of the daily intake) is negligible and systemic effects are very unlikely to occur. Furthermore, no risk is arising from the oxidized Phosphorus species such as Hypophosphite, Phosphite, and Phosphate which are part of the daily diet.

 

Taking into account the above mentioned calculations/arguments a repeated dose study is scientifically not justified since the systemic exposure to elemental Phosphorus is not expected to occur and exposure to the oxidized Phosphorus species (Hypophosphite, Phosphite, and Phosphate) is negligible compared to the normal daily Phosphorus uptake via diet.

Therefore, it can reasonably be deduced that Red Phosphorus does not exert systemic toxic effects after repeated application and thus does not have to be classified according to the criteria laid down in the EU Dangerous Substances Directive (67/548/EEC) and in the EU Classification Labelling and Packaging Regulation (1272/2008/EC).