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Diss Factsheets

Administrative data

Description of key information

According to the CLP Regulation Annex VI Table 3.1, the concentration limit for corrosivity of NaOH is considered to be 2%. Up to the most recent ATP (29th; April 2004), this has not been changed. Therefore, 2% is taken forward to the risk characterization as concentration limit for corrosivity.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Additional information

When in contact with water, the constituents of Feropur will be degraded within seconds to Na+,OH-and H2. Consequently, Na2O and NaH are considered to be too short-living and hence irrelevant for the assessment of environmental and toxicological effects. Based on the very quick and complete degradation of Na2O and NaH to NaOH, the risk assessments for the environment and humans are based on the properties of NaOH and Na2CO3.

This approach was discussed with ECHA (see attached document: "Strategy paper Feropur ECHA 090813.pdf"). ECHA agreed on this approach (see attached document "reply ECHA 090902.pdf").

The hazards of NaOH and Na2CO3 for the environment are caused by the hydroxyl ion and carbonate ion, respectively, and hence by an effect on the pH, i.e., both ions will increase the pH. However, the impact on the pH-effect of the carbonate ion is much weaker than the impact of the hydroxyl ion. In the SIDS dossier of sodium carbonate (SIDS dossier for sodium carbonate, 2002, Table 1, page 10, see attached document) it is outlined that 603 mg sodium carbonate/L are needed to increase the pH of distilled water to a pH of 11. To cause the same effect with sodium hydroxide, only 40 mg sodium hydroxide/L is needed (SIDS dossier for sodium hydroxide, 2002, Table 1, page 10, see attached document). Hence, the effects of sodium carbonate are about 15 times weaker than for sodium hydroxide. In addition, the concentration of sodium carbonate is only about 5% in Feropur. When in contact with water, the degradation products consists to about 95 % of sodium hydroxide and about 5% of sodium carbonate (see attached document "Strategy paper Feropur ECHA 090813.pdf"). When multiplying the concentration with the efficiency of sodium carbonate relative to sodium hydroxide (1/15th), i.e., 5%*1/15, the impact of sodium carbonate in Feropur would be about 0.3% when compared to the effect of sodium hydroxide in Feropur. Na2CO3 is registered as food additive E500i and may be added quantum satis to food and is therefore considered to be a substance of “low priority".

Based on the same mode of action and the much weaker effect of sodium carbonate in combination with the much lower content of sodium carbonate in Feropur when compared to sodium hydroxide, it can be concluded that the risk of Feropur is sufficiently described by the risk resulting from sodium hydroxide alone.

 

According to the studies of York et al (1996), Griffiths et al (1997), and Dykes et al (1995), which were considered valid by the EU RAR of sodium hydroxide (2007; section 4.1.2.3.1, page 66-67), a concentration of 0.5% was already irritating for an exposure up to 1 hour. The response was so vigorous that exposure for a greater duration was not undertaken. Sheena et al (1977) observed that 1% w/v aqueous solution of sodium hydroxide was slightly irritating and 5% w/v aqueous solution was irritating. Liebsch et al (1995) and Jacobs et al (1990) reported that 5% was already corrosive, although the test system was unsuitable and insufficient details were provided, respectively. According to the CLP Regulation Annex VI Table 3.1the concentration limit for corrosivity of NaOH is considered to be 2%. According to Jacobs et al (1992), a concentration of 2% was irritating to the eyes due to the mean score for conjunctivitis and the mean score for corneal opacity (test conducted according to OECD Guideline 405), a concentration of 1% NaOH is not irritating to the eyes. Reer (1976) reported that 10% sodium hydroxide caused irreversible effects on the eye and 0.5% caused slight irritation to the eyes. Morgan et al (1987) reported that a concentration of 0.4% NaOH was mild irritating and 1.2% was corrosive.


Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: irritating

Justification for classification or non-classification

- According to the CLP Regulation No 1272/2008 Annex VI Table 3.1, the concentration limit for corrosivity to the skin of NaOH is considered to be 2% (classification as Skin Corr.1B).

- According to the CLP Regulation No 1272/2008 Annex VI Table 3.1, NaOH is a strong corrosive at a concentration > or = 5% (classification as Skin Corr.1A)

- According to the CLP Regulation No 1272/2008 Annex VI Table 3.1, the concentration range for eye/skin irritation is 0,5 % ≤ C < 2 % (classification as Skin Irrit. and Eye Irrit. 2)

These classifications will also be used for Feropur.