Short version ~ USP modified (Lansinoh) is about pure as it is going to come.
Research to back it up ~
lanolin (lan·o·lin) (lan¢o-lin) [USP] [lana + oleum] the purified waxlike substance from the wool of sheep, cleaned, deodorized, and decolorized; mixed with 25 to 30 per cent water, it is used as a water-in-oil ointment base.
modified lanolin, [USP] lanolin that has been processed to reduce the amount of free lanolin alcohols and detergent and pesticide residues.Source
USP 28 (Modified Lanolin). It is Lanolin that has been processed to reduce the contents of free lanolin alcohols and detergent and pesticide residues.Source
Lansinoh is guaranteed to contain less than 1 part per million (.000001) or 10 thousandths of I% (.0001 %) total combined residues - the absolute lowest value achievable with present technology.
Lansinoh will never contain more than 1.5% free lanolin alcohols or 0.5% detergent residues - rendering it truly hypoallergenic,
even for those allergic to wool or other refinements of lanolin. Lansinoh Laboratories will always provide a current Certificate Analysis for review. Lansinoh is the only lanolin that contains no preservatives or additives of any kind.Source
Hydrous lanolin versus anhydrous lanolin
When referring to the three papers that use lanolin, care needs to be taken as different names are used in each paper. Anhydrous lanolin is known as USP modified lanolin and is also referred to as modified lanolin (medical grade) in comparison to hydrous lanolin which is now discontinued due to concerns about pesticide residues.SourceDifferent types of USP lanolin
USP Ultrafine Grade
Pharmaceutical GradeModified USPSource
I have to say that I'm fairly positive that Lansinoh is NOT the same as
PureLan. I have had several patients react allergically to PureLan and not
one with Lansinoh. Sorry, but it's got a great track record at least with
-- Chris Hafner-Eaton, PhD, MPH, CHES, IBCLCSource