PAC Database - Detailed Chemical Data

Chemical Identity
Chemical CAS# UN# Health Code Numbers
Butyne-1,4-diol, 2-; (1,4-Butynediol) 110-65-6
Formula Synonyms
Physical Properties
Mol Wt State MP (°C) BP (°C) VP (Hg) VP (°C) SG LEL (ppm)
86.09 S 50 238 25 1.115 @ 20°C
PAC Values
PAC Values (Original Units: mg/m3)
1.1 3.4 21
Converted PAC Values (ppm)
0.31 0.97 6.0
Technical Basis
A review of available sources identified the following: MAK-TWA, LCLo, and LD50 for intraperitoneal and oral routes. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to type of exposure, species, and route according to the hierarchies stated in Sections 3.3.1, 3.3.2, and evaluated using factors in Tables 3.2, 3.3, and 3.4. The LCLo was scaled to a 60-minute equivalent using the ten Berge equation (Section 3.3.4). Although the LCLo is typically preferable according to the data hierarchy, the resulting TEEL value (~5 mg/m3) is on the order of the TEEL-1 and is an order of magnitude less that all other TEEL estimates. Due to this, and a higher statistical relevance (see Appendix A) the lowest oral LD50 was selected as the TEEL-3 basis. TEEL-2 values were calculated according to Table 3.5. The MAK-TWA was selected as the TEEL-1 basis.
• TEEL-1 = MAK-TWA (0.36 mg/m3) x 3
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat oral LD50 (104 mg/kg)
The review generated TEEL values that are inconsistent with those in Rev. 29A. Although Rev. 29A and the current TEELs employ consistent methodology, the Rev. 29A TEEL-3 data was not found during current research and the current data results in a more conservative value. The TEEL-2 is more conservative, due to it derivation from this TEEL-3. The Rev. 29A and current TEEL-1 source are consistent, but calculations resulted in different values.
Toksikologiya Novykh Promyshlennykh Khimicheskikh Veshchestv. Toxicology of New Industrial Chemical Substances. For English translation, see TNICS, 7(13), 1965; National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 8066, 2-Butyne-1,4-diol. Retrieved from
Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 649; Section 3.3 Non-Human Toxicity Values, retrieved from:
Journal of Pharmacy and Pharmacology., 26(597), 1974 [PMID:4155724]; National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 8066, 2-Butyne-1,4-diol. Retrieved from
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