Dermatitis sensitising

Nickel parts of bows have been responsible for hand dermatitis. Sensitisation from the metal alloys of brass instruments is extremely rare. 

Toxic chemicals can enter the body in various ways, in particular by swallowing, inhalation and skin absorption. Skin absorption may lead to dermatitis and this can be a most annoying complaint. Whereas some chemicals may have an almost universal effect on human beings, others may attack only a few persons. A person who has worked with a given chemical for some years may suddenly become sensitised to it and from then on be unable to withstand the slightest trace of that material in the atmosphere. He may as a result also be sensitised not only to the specific chemical that caused the initial trouble but to a host of related products. Unfortunately a number of chemicals used in the plastics industry have a tendency to be dermatitic, including certain halogenated aromatic materials, formaldehyde and aliphatic amines. 

Environment and health-related problems Water-soluble chrome(VI) compounds in the wet cement or mortar have a highly sensitising effect and are up to 90% the cause of allergic cement dermatitis (cement eczema, bricklayer s itch ). The high alkalinity (pH = 13) of cement aids the development of this contact eczema. Bricklayer s itch is one of the most frequent professional diseases in the construction industry. 

The interaction of a chemical (hapten) with epidermal proteins (carrier) can result in a hapten-carrier complex capable of activating skin-associated lymphoid tissue (sensitisation) and dissemination of antigen-specific T l)unphocytes (induction). Subsequent encoimter with the same or cross-reactive chemicals can result in the elicitation of a characteristic inflammatory skin reaction. The clinical condition is referred to as allergic contact dermatitis and is characterised by erythema, oedema, vesiculation and pruritus. Allergic contact sensitisation is, therefore, classed as a cell-mediated immunological response to chemicals that contact and penetrate the skin. 

There are a number of models for detecting allergic contact dermatitis in guinea pigs. The maximisation test developed by Magnussun and Kligman is the most widely used and employs both an intradermal and topical sensitisation phase, together with the non-specific stimulation of the immune system by the intradermal injection of Freund s complete adjuvant. 

A negative result in this type of test indicates that the potential to sensitise is extremely low and that human exposure is unlikely to be attended by a significant incidence of sensitisation. Because the test can be overpredictive, some toxicologists recommend that a non-adjuvant test such as the Buehler test should be used if a positive is obtained, to give a more realistic determination of the prevalence of human sensitisation, it should be remembered that contact sensitisation is a persistent condition thus once sensitised to a chemical, an individual is at risk of dermatitis whenever exposed to the same or antigenically cross-reactive chemical, for example, nickel in jewellery. 

Repeated contact of solvents and many other chemicals with the skin may lead to dermatitis, an unsightly and irritating skin disease which is often very hard to cure. In addition, sensitisation to further contact or exposure may occur. 

Caution. Chlorpromazine may cause severe dermatitis in sensitised persons. 

Cutaneous irritation, e.g. directly with nettle (Urtica), or dermatitis following sensitisation with Primula. 

As with any chemical products, persons known to have a history of dermatitis, skin sensitisation or asthma should not work in direct contact with polyurethanes. Ingestion, inhalation, skin contact and eye contact should be avoided. Prolonged contact in any form with the skin may cause localised irritation leading to dermatitis and must be avoided. In case of skin contact, remove excess with clean cloth. Clean with proprietary cleansing cream and wash with soap and water. Do not use any solvent. Contaminated clothing should be removed immediately and not reused until it is laundered. 

Allergic dermatitis is the result of hypersensitivity to a sensitising agent. 

Basketter D, Angers-Loustau A, Casati S, ECVAM (2012) ECVAM progressing skin sensitisation alternatives for hazard identification. Contact Dermatitis 66(Suppl 2) 24... 

Divkovic M, Pease CM, Gerberick GF, Basketter DA (2005) Hapten-protein binding from theory to practical application in the in vitro prediction of skin sensitisation. Contact Dermatitis 53 189-200... 

E.3 ContactedlerpfensThc sesquiterpene lactones of the Asteraceae, e.g. chrysanthemums, asters and daisies, are well-known causes of contact allergic dermatitis. Patients with such allergies should avoid (and should be advised to avoid) herbs such as Artemisia (Mugwort), Chamomile, Yarrow (Achillea). Feverfew, Echinacea-inA Arnica because of cross-sensitisation. 

Allergic skin reactions sometimes develop following contact with mercury. The elemental liquid metal and the vapour can both be absorbed through the skin ( 15%) so contributing to toxicity. Sensitisation to contact leads to outbreaks of dermatitis with redness, itching, rash and swelling which can spread over the body. This can occur in people occupationally exposed to mercury, such... 

Early experimentation with Anacardium occidentale and cardols present in Australian species indicated that susceptibility to cardols was more prevalent than to anacardic acids or cardanols. However, more recent studies with Ginkgo biloba have found that anacardic acids were good sensitisers, while cardanols failed to induce allergic contact dermatitis [297]. 

Phenoi did not cause any signs of skin sensitisation in tests conducted with guinea pigs (modified BuehlerTest, Itoh 1982) and mice (Mouse Ear Swelling Assay, Descotes 1988), and there is no evidence of allergic contact dermatitis in humans. Therefore, labelling with R 43 is not warranted" (p.88). 

Any unpolymerised oligo-polyester left in the composite system has been shown to be responsible for sensitisation and allergic contact dermatitis in use [69, 70]. 

Toxicology Exposnre is usually by inhalation. Benzoyl peroxide breaks down in contact with skin, prodncing benzoic acid and oxygen, neither of which are significantly toxic. Benzoyl peroxide is a strong irritant to mucous membranes (above 12.2 mg/m ), and can initiate both primary irritation and sensitisation dermatitis. It is a suspected cancer promoter on skin. lARC conclnded that there is no solid evidence for its carcinogenicity. 

The ability of local anaesthetics to produce contact dermatitis is well known (Rothman et al. 1945 de Swarte 1972). Hence patch tests may be of relatively greater value than in other allergies. In fact, cross-sensitisation with p-aminoben-zoate (used topically to prevent sunburn) was first reported in contact dermatitis studies (Gaul 1955). 

The older antifungal agent, phenylmercuric borate, used still in the control of athlete s foot, is a more common and more potent skin sensitiser. In a trial reported by Bandmann (1966) more than 10% of patients developed contact allergic dermatitis, and cross-reactions with other mercury compounds can occur. 

Sensitisation to the topical antifungal agent, Mycanodin is difficult to quantitate. The active antifungal is 3-(2-hydroxy-5-chlorophenyl)pyrazole and this can cause contact allergic dermatitis and photoallergic reactions (Fig. 4 Burckhardt et al. 1968). The same authors showed, however, that an antihistamine co-formu-... 

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