A doctor asks us for a formula to eliminate remnants of ingrown and largely removed toenails. The doctor knows that a formula would exist with a BEP. % phenol in present.

I eventually found an ointment with a fairly high concentration of phenol: phenol 5g, lard 30g. The lard can, I think, perhaps be replaced by Unguentum simplex. Other phenol ointments usually contain 1% phenol.

about ingrown nails I find back on the Internet:

http://www.helendemeesters.nl/ingegroeide_nagel.htm
Http://www.flevovoet.nl/index.php?id=klachten

from this I conclude that the concentration is acceptable.