Patch testing with colophony

Colophony (rosin) has been fractionated into 2 parts, an acidic and a neutral fraction. Routine patch testing with neutral components gives positive reactions at a 40% higher frequency than routine patch testing with colophony (20%) (w/w in pet.). A concentration of 60% colophony is suggested for routine patch testing.     

Allergenicity of rosin (colophony) esters

In the esterification of rosin with glycerol, the main compound formed, glyceryl triabietate, shows low allergenic activity. In this study, compounds formed in smaller amounts, when abietic acid (main component in rosin) was esterified with glycerol, were identified as glyceryl-1-monoabietate (GMA), glyceryl-1,2-diabietate (GDA_1,2) and glyceryl-1,3-diabietate (GDA_1,3), using nuclear magnetic resonance (NMR), infra-red (IR) and mass spectrometry (MS) analyses. According to animal experiments, GMA was a contact allergen. No cross-reactivity was seen to allergens in unmodified rosin. Some patients allergic to unmodified rosin reacted when tested with GMA. No reactions were seen to the 2 diabietates. Some patients also reacted to commercial glycerol-modified rosins. GMA together with unmodified abietic acid were identified in these rosin samples. The reactions seen in rosin-sensitive patients to commercial glycerol-esterified rosins probably derive from the unmodified material still present in the product, but could also be the result of GMA obtained from the glycerol derivatization.     

Hydrogenation reduces the allergenicity of colophony (rosin)

Abietic acid is the main component of rosin. It is readily oxidized by air and its oxidation products are considered to be mainly responsible for the allergenic effect. Hydrogenation of the conjugated double bonds of abietic acid decreases its susceptibility to air oxidation and would thus reduce the allergenicity of rosin. Portuguese gum rosin was therefore hydrogenated and its allergenicity was compared with that of unmodified rosin in animal experiments and by patch testing in humans. Its sensitizing potential was determined in 2 studies. No response was found according to the FCAT method while the GPMT gave significant response in the animals challenged with the highest test concentration. Hydrogenated rosin showed no eliciting activity in animals induced with unmodified rosin according to the GPMT method. A marked decrease was found in the frequency of allergic reactions to hydrogenated rosin compared to the reactions to unmodified rosin in patients with known allergy to gum rosin. We conclude that elimination of the unsaturated non-aromatic compounds by hydrogenation considerably reduces the allergenicity of Portuguese gum rosin.     

The allergenicity of glycerol esters and other esters of rosin (colophony)

To investigate whether esterification of rosin with polyalcohols changes its allergenic potential. abietic acid, the main component of rosin, was esterified with glycerol at high temperature. The major product formed was isolated and identified, using nuclear magnetic resonance (NMR). infra-red IR) and mass spectrometry (MS) analyses, as glyceryl triabietate (GTA), an ester between one glycerol molecule and 3 abietic acid molecules. According to animal experiments GTA was not allergenic and no cross-reactivity was seen to allergens in unmodified rosin, when testing patients allergic to unmodified rosin, no reactions were found to GTA. Some of the patients reacted to glycerol- and pentaerythritol-esterified rosins. According to HPLC analyses, these esterified rosins still contained unmodified material to which the patients may have reacted. It seems that the esterification of rosin with poly alcohols such as glycerol reduces its allergenic activity, possibly because of the formation of much larger molecules with reduced bioavailability. However, making methyl esters of rosin causes little alteration in the molecular weights of the components and. when unmodified and methylated rosin were tested in patients, we saw no difference between the 2 forms.     

Inhibitory effect of zinc oxide on contact allergy due to colophony

Contact allergy to a wound dressing with an adhesive mass consisting of colophony, zinc oxide and rubber (Mezinc) was studied in 179 patients with a history of eczema. 12 patients were found to be allergic to colophony, whereas only 4 of these patients also showed a positive patch test reaction to the wound dressing. 14 patients with verified moderate contact allergy to colophony were patch tested with adhesive mass (10%), Portuguese colophony (10%), zinc oxide (10%), purified resin acids (10%), and Portuguese colophony (10%), in combination with zinc oxide. Only 3 patients reacted to the adhesive mass, whereas all patients showed a positive patch test reaction to Portuguese colophony. A combination of zinc oxide (10%) with Portuguese colophony (10%) provoked a positive patch test reaction in only 5 of these 14 patients. An allergic reaction to abietic acid (90-95% purity) was found in 7 patients and to neoabietic acid (99 + %) in 3 patients, whereas no reactions to dehydroabietic (99 + %), isopimaric (99 + %) or levopimaric acids (98 + %) were found.     

Patch testing with allergens from modified rosin (colophony) discloses additional cases of contact allergy

Most rosin (colophony) used today is chemically modified. Will contact allergy 10 modified rosin be overlooked when testing is performed with only unmodified rosin in the standard series? 2 components from modified rosins. maleopimaric acid (MPA) and glyceryl 1-monoahietale (GMA), earlier identified us contact allergens, were added to the patch lest standard series. Some commonly-used modified rosin products were also tested. Positive reactions were observed to the modified components MPA and GMA. Of the patients with positive reactions to MPA and GMA. several did not react to unmodified rosin in the standard series. No reaction was observed to the modified rosin products without a concomitant reaction to unmodified rosin. The positive reactions observed to the modified rosins may be due to residual unmodified material in the product, but a possible contribution from allergenic modified rosin components cannot be disregarded. When u patient's history indicates a rosin allergy, but a negative response to unmodified rosin in the standard series is observed, additional testing with GMA and MPA or, second best, with glycerol-esterified rosin and maleic-anhydride-modified rosin is recommended. Some modified rosin products, which could be used for additional testing, are suggested.     

Experiences with Freund''s complete adjuvant test (FCAT) when screening for contact allergens in colophony

A procedure, using Freund's complete adjuvant test (FCAT), for the determination of the allergenic potential of fractions and components in colophony of the gum rosin type is described and discussed. Gum rosin was shown to be a potent sensitizer in 11 test series (153 animals). FCAT is compared with the guinea pig maximization test (GPMT). Gum rosin was a potent sensitizer according to this method as well. The FCAT method was found to be advantageous over the GPMT method in that it is technically simpler to use and a smaller amount of test substance is needed. However, closed challenge was preferred to the prescribed open challenge. The importance of statistical evaluation of the results obtained in predictive testing is stressed.     

Oxidation of resin acids in colophony (rosin) and its implications for patch testing

Commercial preparations of colophony (rosin) used for patch testing are made from unmodified rosin in pet. and may be stored for some considerable time before being used. This would be satisfactory if the composition and dermatological activity of the preparations were both reproducible and stable, but investigations by the authors have shown that the resin acids undergo progressive and substantial oxidation and that the dermatological activity of the preparations increases significantly with time. This may be a cause of inconsistent patch test results unless the composition can be stabilized. Gas liquid chromatography (GLC) analysis of a raw rosin sample and its commercial patch test preparation has shown that they both contained the same resin acids, but the concentration of the abietic type resin acids was found to be lower in the patch test preparations. The degradation of resin acids is due to their atmospheric oxidation, which may occur during the preparation and storage of the commercial rosin patch test preparation. The susceptibility of individual resin acids to atmospheric oxidation was demonstrated by analysing a sample of raw Portuguese gum rosin, which was then left exposed to air and light. Most of the resin acids were found to undergo oxidation at a rate which gradually diminished. More importantly, it is presumed that the concentration of oxidized resin acids increased correspondingly, and these have been shown to be more dermatologically active than the unoxidised resin acids. The rate of decrease of resin acid concentration was found to be in the following order: neoabietic > levopimaric and palustric > abietic > dehydroabetic acid. The pimaric type resin acids were found to be relatively inert to atmospheric oxidation when compared with the abietic type resin acids. Patch testing with the resulting partly oxidized Portuguese rosin produced positive reactions at a 35% higher frequency than the raw Portuguese rosin. The study demonstrates that the allergic potential of unmodified rosin may increase with exposure to air and light. It is therefore recommended that rosin preparations are analysed routinely as part of a quality control programme, which will enable better validation and comparison of patch test results from different dermatological centres. Since the oxidized resin acids are the main allergens in unmodified rosin, it is important that the concentration of the oxidized resin acids is kept high as well as constant in commercial patch test preparations.     

Airborne contact dermatitis from unexpected exposure to rosin (colophony)

We report 3 cases of contact dermatitis in rosin-sensitive individuals caused by exposure to airborne rosin components from different sources. Case no. 1 was a female office worker with a facial dermatitis caused by rosin components which emanated from the linoleum floor covering in her office. Floor material containing wood flour and rosin was released into the air, causing a facial dermatitis in the rosin-sensitive subject. Case no. 2 involved a woman who worked in a factory producing dairy product cartons and had a dermatitis on her lower legs, lower arms and upper chest. Her dermatitis was caused by dust from the paper cartons and contact allergy to rosin components probably aggravated her dermatitis. Case no. 3 was a female office worker with a relapsing dermatitis on her eyelids. Her dermatitis was caused by a rosin-containing floor polish, which was seen as a powder on the office floor. Extracts of suspected material and products were patch tested and analysed for the presence of rosin components with HPLC and GC techniques. A discussion and recommendations on chemical analyses of rosin components follow. We conclude that a thorough investigation, including chemical analyses, can rule out non-specific diagnoses and offer a solution to the patient's skin problems.     

Is abietic acid the allergenic component of colophony?

In order to investigate whether abietic acid itself is the allergenic component of colophony, 2 commercial samples were extensively purified and tested in guinea pigs and in colophony-sensitive patients. In the modified FCAT method, sensitization was obtained with Portuguese colophony and when challenged with purified abietic acid, the animals showed no reaction. In the GMPT method, the animals were exposed to purified abietic acid. Challenging with 2 different samples of it gave no significant reaction. When patch tested, patients sensitive to colophony showed no reactions to abietic acid which had been purified immediately before the test. It is concluded that abietic acid itself is not a contact allergen.     

Concomitant development of photoallergic contact dermatitis from ketoprofen and allergic contact dermatitis from menthol and rosin (colophony) in a compress

We describe a case of a 40-year-old non-atopic woman with recurrent leg ulcers because of the factor V Leiden mutation who developed a severe eczematous lesions of the skin surrounding an ulcer of the right leg after the use of a protease-modulating matrix (Promogran, Johnson and Johnson, Gargrave, Skipton, UK). The patient was patch tested with the SIDAPA (Italian Society of Allergological, Occupational and Environmental Dermatology) standard series, a piece of the device as is, of the bovine collagen (Zyderm, Collagen Corporation, Palo Alto, CA, USA) as is, a piece of the gauze containing only regenerated oxidized cellulose (Tabotamp, Johnson and Johnson, Gargrave, North Yorkshire, UK) and of a fold towels in pure cellulose (Foscart, Bassano del Grappa, Italy). Patch tests gave a positive reactions to nickel sulphate and Promogran as is. We showed that the sensitizing agent was regenerated oxidized cellulose, a substance the treatment of ulcers and as is in and in combination with collagen in surgery for intraoperative hemostasis. The case reported suggests that regenerated oxidized cellulose can cause allergic contact dermatitis.     

Contact allergy to dehydroabietic acid derivatives isolated from Portuguese colophony

7-oxodehydroabietic acid and 15-hydroxydehydroabietic acid were isolated as their methyl esters from Portuguese colophony of the gum rosin type and identified as contact allergens. Another oxidation product of dehydroabietic acid, 15-hydroxy-7-oxodehydroabietic acid, was synthesized and identified as a component of Portuguese gum rosin. 7-oxodehydroabietic acid was found to a be a grade III allergen according to the GPMT method. Guinea pigs induced with gum rosin showed only a low response to the isolated compounds, while patients with a known allergy to gum rosin reacted to a greater extent. The results imply that the content of oxidized dehydroabietic acids in gum rosin is too low to give a marked sensitization in the animals. However, the patients might have come in contact with the allergens in technically modified rosins. The compounds showed a pattern of cross-reactivity in the animal experiments as well as among the patch tested patients.     

Allergenic potential of abietic acid, colophony and pine resin-HA

Resin acids are considered to be the main allergens in colophony (rosin). Tall oils also contain resin acids and may then be potential sensitizers. A resin acid concentrate (pine resin-HA) together with Chinese colophony were included in our standard series and applied on 563 patients with contact dermatitis. Fourteen showed an isolated sensitivity to colophony and two to pine resin-HA. Six patients reacted to both test compounds. Guinea pig maximization tests (Magnusson & Kligman 1969) showed that pine resin-HA (2 series) was a grade I allergen, abietic acid a grade III allergen and colophony a grade IV allergen. The risk that the resin acids in tall oils would induce contact sensitivity to workers exposed to tall oil-containing products like cutting fluids and cleansing agents is considered to be minimal.     

Temporal trends of preservative allergy in Denmark (1985–2008)

Background: Most cosmetics and industrial products contain preservatives. Preservative allergy is common and, historically, changing contact allergy epidemics caused by preservatives have been observed. In 1997, Alan Dillarstone predicted a stable development of preservative allergy following mandatory ingredient labelling on cosmetic products. Objectives: To investigate the development in the prevalence of preservative allergy in Denmark over a 24‐year period (1985–2008) and to challenge the prediction made by Dillarstone. Patients/Methods: A retrospective analysis of patch test data was performed (n = 18179). Comparisons were made using a χ² test. Logistic regression analyses were used to test for associations. Results: The development of preservative allergy mirrored those of other European patch test centres. The development was not dependent on sex or age group. The prevalence was higher among women and those aged 41–60 years. Formaldehyde allergy was persistently prevalent over the study years. The overall prevalence of preservative allergy increased significantly (P_trend = 0.001), mainly because of patch testing with additional preservatives in recent years. Conclusions: Dillarstone's prediction was confirmed as the prevalence of contact allergy to individual preservatives remained relatively stable. However, the overall burden of preservative allergy seemed to increase. Introduction of new preservatives may add to the burden of contact allergy.