Why isn't calcium carbide more corrosive?
In these Safety Data Sheets for $\ce{Ca(OH)2)}$ and for $\ce{CaC2}$, both compounds are rated at &quot;Causes serious eye damage – Category 1&quot; and &quot;Causes skin irritation – Category 2&quot;.
That said, $\ce{CaC2}$ is often sold as pellets or &quot;stones&quot;. Because of large particle size, only a small amount of $\ce{Ca(OH)2)}$ is produced at a time from the action of water on $\ce{CaC2}$ since the release of acetylene bubbles slows penetration of water into the pellets.
$\ce{Ca(OH)2)}$, on the other hand, is more often sold as a finely divided powder. That dust is, in my experience more of a respiratory hazard. The &quot;lime&quot;, as it's slaked in water, also evolves considerable heat, which exacerbates the caustic effect on skin.
Of course, $\ce{CaC2}$ has it's own hazards... it can cause considerable damage from an acetylene explosion.