Editing Lanolin (section)

== Standards and legislation ==

In addition to general purity requirements, lanolin must meet official requirements for the permissible levels of [[pesticide]] residues. The Fifth Supplement of the [[United States Pharmacopoeia]] XXII published in 1992 was the first to specify limits for 34 named [[pesticide]]s. A total limit of 40&nbsp;[[parts per million|ppm]] (i.e. 40&nbsp;mg/kg) total pesticides was stipulated for lanolin of general use, with no individual limit greater than 10&nbsp;ppm.<ref name=lanolin_book/>

A second monograph also introduced into the US Pharmacopoeia XXII in 1992 was entitled 'Modified Lanolin'. Lanolin conforming to this monograph is intended for use in more exacting applications, for example on open wounds. In this monograph, the limit of total pesticides was reduced to 3&nbsp;ppm total pesticides, with no individual limit greater than 1&nbsp;ppm.

In 2000, the [[European Pharmacopoeia]] introduced pesticide residue limits into its lanolin monograph. This requirement, which is generally regarded as the new quality standard, extends the list of pesticides to 40 and imposes even lower concentration limits.

Some very high-purity grades of lanolin surpass monograph requirements. New products obtained using complex purification techniques produce lanolin esters in their natural state, removing oxidative and environmental impurities resulting in white, odourless, [[hypoallergenic]] lanolin. These ultra-high-purity grades of lanolin are ideally suited to the treatment of dermatological disorders such as [[eczema]] and on open wounds.<ref>{{cite journal |last1=Arden Jones |first1=M. R. |last2=Steel |first2=I. |last3=Powell |first3=S. M. |journal=British Journal of Dermatology |volume=147 |issue=Suppl. 62 |pages=71 |date=July 2002 |doi=10.1046/j.1365-2133.147.s62.19.x  |title=British Contact Dermatitis Group: Summaries of Papers }}</ref>

Lanolin attracted attention owing to a misunderstanding concerning its sensitising potential.<ref name="steel">{{cite journal |last=Steel |first=I. |title=Lanolin Allergy: Hype or Hypersensitivity? |journal=Journal of the National Eczema Society (Exchange) |issue=75 |pages=16–17 |date=1994 }}</ref> A study carried out at New York University Hospital in the early 1950s had shown about 1% of patients with dermatological disorders were allergic to the lanolin being used at that time.  By one estimate, this simple misunderstanding of failing to differentiate between the general healthy population and patients with dermatological disorders exaggerates the sensitising potential of lanolin by 5,000–6,000 times.<ref name = steel/><ref>{{cite conference|last1=Steel |first1=I. |last2=White |first2=I. R. |last3=Beck |first3=M. H. |date=1995 |title=Dilemmas in Lanolin Sensitivity |conference=10th International Symposium on Contact Dermatitis |location=[[Nagoya]]}}</ref>

The European [[Cosmetics Directive]], introduced in July 1976, contained a stipulation that cosmetics which contained lanolin should be labelled to that effect. This ruling was challenged immediately, and in the early 1980s, it was overturned and removed from the directive. Despite only being in force for a short period of time, this ruling did harm both to the lanolin industry and to the reputation of lanolin in general.<ref name=steel/> The Cosmetics Directive ruling only applied to the presence of lanolin in cosmetic products; it did not apply to the many hundreds of its different uses in dermatological products designed for the treatment of compromised skin conditions.

Modern analytical methods have revealed lanolin possesses a number of important chemical and physical similarities to human [[stratum corneum]] lipids; the [[lipids]] which help regulate the rate of water loss across the [[epidermis]] and govern the hydration state of the skin.<ref name=lanolin_book/><ref name="Clark93Poster">{{cite report|first1=E. W.|last1=Clark|first2=I.|last2=Steel|title=Poster No.&nbsp;2|publisher=American Academy of Dermatology|location=Washington, DC|date=1993}}</ref><ref name="Clark93">{{cite journal |last1=Clark |first1=E. W. |last2=Steel |first2=I. |journal=Journal of the Society of Cosmetic Chemists |volume=44 |issue=4 |pages=181–195 |date=1993 |title=Investigations into biomechanisms of the moisturizing function of lanolin |url=http://journal.scconline.org/pdf/cc1993/cc044n04/p00181-p00195.pdf |access-date=29 October 2016 |archive-date=29 October 2016 |archive-url=https://web.archive.org/web/20161029114633/http://journal.scconline.org/pdf/cc1993/cc044n04/p00181-p00195.pdf |url-status=live }}</ref>

[[Cryogenic]] [[scanning electron microscopy]] has shown that lanolin, like human stratum corneum lipids, consists of a mass of liquid crystalline material. [[Polarized light microscopy|Cross-polarised light microscopy]] has shown the [[lamellar|multilamellar]] [[Vesicle (biology)|vesicle]]s formed by lanolin are identical to those formed by human stratum corneum lipids. The incorporation of bound water into the stratum corneum involves the formation of multilamellar vesicles.<ref name=lanolin_book/><ref name=Clark93/>

Skin [[bioengineering]] studies have shown the durational effect of the [[emollient]] (skin smoothing) action produced by lanolin is very significant and lasts for many hours. Lanolin applied to the skin at 2&nbsp;mg/cm<sup>2</sup> has been shown to reduce roughness by about 35% after one hour and 50% after two hours, with the overall effect lasting for considerably more than eight hours.<ref name=lanolin_book/> Lanolin is also known to form semiocclusive (breathable) films on the skin.<ref name = barnett/> When applied daily at around 4&nbsp;mg/cm<sup>2</sup> for five consecutive days, the positive moisturizing effects of lanolin were detectable until 72&nbsp;hours after final application.<ref name=lanolin_book/> Lanolin may achieve some of its moisturizing effects by forming a secondary moisture reservoir within the skin.<ref name=Clark93Poster/><ref name=Clark93/>

The barrier repair properties of lanolin have been reported to be superior to those produced by both [[Petroleum jelly|petrolatum]] and [[glycerol]].<ref name=lanolin_book/> In a small clinical study conducted on volunteer subjects with terribly dry ([[Xeroderma|xerotic]]) hands, lanolin was shown to be superior to petrolatum in reducing the signs and symptoms of dryness and [[Skin condition#Secondary lesions|scaling]], cracks and abrasions, and pain and itch. In another study, a high purity grade of lanolin was found to be significantly superior to petrolatum in assisting the healing of superficial wounds.