Substantiation of maximum allowable concentration of 2-ethylhexanoic acid in the air of the working area

Introduction. 2-Ethylhexanoic acid is widely used in various industries: in the production of plastics, paints, enamels, varnishes, as a preservative, corrosion inhibitor, wetting agent, in the production of low molecular weight aromatic and aliphatic esters.

In order to ensure the safety of workers engaged in the production of 2-ethylhexanoic acid in the Russian Federation, it became necessary to conduct research to substantiate the hygienic norms for the content of vapors and aerosols of the substance in the air of the working area.

In accordance with HNs 1.1.701, if a substance belongs to a homologous series, the representatives of which have an approved MAC value for the air of the working area, the maximum allowable concentration can be set based on a comparison of known toxicometric parameters. According to Sanitary rules and norms 1.2.3685-21, for substances similar in structure, physicochemical properties and biological effects — hexanoic and isohexanoic acids — the values of the maximum single allowable concentration in the air of the working area are set at the level of 5 mg/m³, vapor, hazard class 3. An analysis of international databases showed that 2-ethylhexanoic acid is regulated in the air of the working area in Belgium (TWA 5 mg/m³, vapor and aerosol mixture).

The purpose of the work is to substantiate the hygienic norms for 2-ethylhexanoic acid in the air of the working area in the Russian Federation.

Material and methods. The materials used were domestic and international databases, reports, research protocols, scientific articles and monographs containing information on the physicochemical and toxic properties of hexanoic, 2-ethylhexanoic, 4-methylpentanoic and 2-propylpentanoic acids. The research methodology consisted of a comparative analysis of toxicometric parameters of substances similar in structure, physicochemical properties and biological effects and calculation of safe concentrations of 2-ethylhexanoic acid in the air of the working area according to established NOAEL values.

Results and discussion. A comparative analysis of the toxicometric parameters of hexanoic, 2-ethylhexanoic, 4-methylpentanoic and 2-propylpentanoic acids was carried out. Substantiate for the value of the maximum allowable concentration of 2-ethylhexanoic acid in the air of the working area is based on: 1) NOAEL at the level of 180 mg/kg/day according to the general toxic effect established in studies on male mice when administered intragastrically for 92–93 days; 2) NOAEL at 100 mg/kg/day for developmental toxicity established in rat studies when administered intragastrically during days 6–15 of pregnancy. 3) MAC values for structurally similar analogues.

Limitations. The study is limited to the study of open literature sources describing the toxicological characteristics of 2-ethylhexanoic acid.

Conclusion. As a hygienic norms in the air of the working area for 2-ethylhexanoic acid, the maximum single allowable concentration is recommended at the level of 5 mg/m³, vapor + aerosol, hazard class 3. The recommended MAC value is provided by the analytical control method MM-25-23 “Measurement of the mass concentration of 2-ethylhexanoic acid in the air of the working area, the atmospheric air of urban and rural settlements by capillary gas chromatography with mass spectrometric detection”, developed by F.F. Erisman Federal Scientific Center of Hygiene, Rospotrebnadzor (the lower limit of determination in the air of the working area is 0,5 mg/m³; number in the Federal Information Fund for Ensuring the Uniformity of Measurements — FR.1.31.2023.47327).

Compliance with ethical standards. The study does not require the submission of a biomedical ethics committee opinion or other documents.

Author contribution:
Khamidulina Kh.Kh. — concept and design of the study, editing, approval of the final version of the article, responsibility for the integrity of all parts of the article;
Tarasova E.V. — concept and design of the study, collection and processing of materials, text writing, editing;
Zamkova I.V. — collection and processing of materials, writing text;
Nazarenko A.K. – editing.

Conflict of interest. The authors declare no conflicts of interest.

Funding. The study had no financial support.

Received: February 05, 2024 / Accepted: March 10, 2024 / Published: April 27, 2024