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Home / Substance database / Sodium hydroxide Substance database · CAS 1310-73-2

Sodium hydroxide

caustic soda

What a safety data sheet for sodium hydroxide and mixtures containing it has to cover – harmonised classification, workplace limits and transport, taken from official sources.

Sources last checked: 14 October 2026 · CLP consolidated version of 1 July 2026 Author: Maximilián Pálffy, chemical engineer This page is not a safety data sheet. We do not publish SDSs of specific products – the figures come from official sources and the binding text is always the legislation itself.
1310-73-2 CAS number
215-185-5 EC number
011-002-00-6 Index number (CLP Annex VI)
UN 1823 / 1824 UN number (ADR)

Harmonised classification

Entry in CLP Annex VI, Table 3: sodium hydroxide; caustic soda.

Annex VI, Table 3

Classification

  • Skin Corr. 1A – skin corrosion, category 1A (H314)
Label elements

Labelling

GHS05 pictogram – corrosion
Signal word: Danger · GHS05
  • H314 Causes severe skin burns and eye damage.
  • Specific concentration limits: Skin Corr. 1A (H314) at C ≥ 5 %; Skin Corr. 1B (H314) at 2 % ≤ C < 5 %; Skin Irrit. 2 (H315) and Eye Irrit. 2 (H319) at 0.5 % ≤ C < 2 %.
  • “May be corrosive to metals” (H290) is not part of the harmonised entry – the supplier assesses it in its own classification.
 Source: CLP, Annex VI, Part 3 and Annex III

Workplace limits and transport

Occupational exposure limits are national. The values below are those of Slovakia; an SDS states the limits of the country where it is supplied, together with their legal basis.

Government Regulation No 355/2006

Occupational exposure limits (Slovakia)

  • 8-hour limit: 2 mg/m³
  • No short-term limit is set
ADR 2025

Transport

  • UN 1823 sodium hydroxide, solid – class 8, packing group II
  • UN 1824 sodium hydroxide solution – class 8, packing group II or III depending on corrosivity
  • Label 8
Sources: Government Regulation No 355/2006, Annex 1 (Slov-Lex) · BAM DGG-Info – ADR 2025

What the SDS must cover

All safety data sheets follow the 16 sections of REACH Annex II. For sodium hydroxide, these points need particular attention:

Section 2 Skin Corr. 1A, H314, pictogram GHS05 and the signal word “Danger”. For mixtures, the specific concentration limits decide: from 5 % sodium hydroxide alone leads to Skin Corr. 1A.
Section 3 For a mixture: name, CAS and EC number, registration number, concentration or range and the specific concentration limits from Annex VI (REACH Annex II, 3.2.3).
Section 8 The national occupational exposure limit with its legal basis – in Slovakia 2 mg/m³ under Government Regulation No 355/2006 – and eye and skin protection.
Section 14 UN 1823 (solid) or UN 1824 (solution), class 8 and the packing group.
The structure of all 16 sections is described in the SDS template.

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Sources

Sources last checked: 14 October 2026. Always use the consolidated versions of the legislation.