But-2-yne-1,4-diol

Endpoint summary

Description of key information

Short description of key information on bioaccumulation potential result:

Expected to metabolize to 4-hydroxy-2-butynaldehyde (4-OH-butynal) and potentially further to 4-hydroxy-2-butyne-monocarboxylic acid and further yet to 2-butyne-1,4-dicarboxylic acid.

Short description of key information on absorption rate:

Dermal Absorption Rate (Estimated): 0.15 mg/cm2-hr.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

1,4 -Butynediol (B3D) is expected to metabolize to 4-hydroxy-2-butynaldehyde (4-OH-butynal) and potentially further to 4-hydroxy-2-butyne-monocarboxylic acid and further yet to 2-butyne-1,4-dicarboxylic acid. In addition, using U.S. EPA DERMWIN v1.43a, the dermal absorption rate of 1,4 -Butynediol is estimated to be 0.15 mg/cm2 -hr (ISP, 2010).

 

Discussion on bioaccumulation potential result:

It is proposed that 1,4 -Butynediol (B3D) is likely metabolized, via ADH, to 4-hydroxy-2-butynaldehyde (4-OH-butynal). Whether 4-OH-butynal is the ultimate toxicant is unknown. 4-OH-butynal could be further metabolized to its corresponding half acid, 4-hydroxy-2-butyne-monocarboxylic acid, via aldehyde dehydrogenase (ALDH). This 4-hydroxy-monoacid could potentially be further metabolized, via ADH and ALDH to the 2-butyne-1,4-dicarboxylic acid, following the general scheme attributed to many alkyl diols. Additionally, the B3D EU Risk Assessment Report (ECB, 2005) suggests that Cytochrome P450 dependent metabolism may also play a role in B3D conversion because a low increase in aminopyrine demethylase has been reported after B3D administration. The potential role of metabolism via glutathione has not been reported.

Discussion on absorption rate:

Using U.S. EPA DERMWIN v1.43a, the dermal absorption rate of 1,4 -Butynediol is estimated to be 0.15 mg/cm2 -hr (ISP, 2010). No measured data were available.