A two-centre study for the evaluation and validation of an animal model for the assessment of the potential of small molecular weight chemicals to cause respiratory allergy.

This study evaluated a single intradermal injection model in the guinea pig with subsequent inhalation challenge and serological analysis as a method to predict the potential of chemicals to induce respiratory allergy. Four known respiratory allergens (trimellitic anhydride, diphenyl methane diisocyanate, phthalic anhydride and toluene diisocyanate (TDI)) were screened by two industrial research laboratories using this protocol. Dinitrochlorobenzene, a potent contact allergen, was included as a negative control material. In both laboratories, the respiratory allergens, but not the contact allergen, induced high titre antigen-specific antibodies in treated animals. The inhalation challenge results were similar in both laboratories but were less conclusive in that exposure to free TDI failed to induce pulmonary responses, probably because it fails to penetrate to the deep lung in sufficient concentration. Although the assay shows promise as a means of identifying chemical respiratory sensitisers, its use as a routine screen for the prediction of the ability of materials to induce respiratory allergy in man is probably questionable.

Simulated consumer exposure to dimethyl ether and propane/butane in hairsprays.

Synopsis The potential human exposures from use of dimethyl ether (DME) and 'liquefied petroleum gas'(LPG) arising from use in hairsprays have been assessed. DME and LPG concentrations were measured in the 'breathing zone' of an experimental manikin and an 'accompanying child' designed to simulate human use of hairsprays in a domestic situation and in the breathing zone of a 'stylist' and 'customer' under salon conditions. Results were expressed as the 10 min time weighted average in the air (TWA10) and as the peak concentration in the breathing zone of the 'user'. Following a 10s use of hairspray containing 50% DME or 26% LPG, TWA10 values for an adult user in a closed room (volume 21 m(3)) were on average 114 ppm and 73 ppm respectively. The child TWA10 values were 89 ppm (DME) and 80 ppm (LPG). Leaving the door open during spraying did not significantly alter these values. The peak concentrations measured in the user breathing zone were 1577 ppm of DME and 671 ppm of LPG. Simulated salon use of a hairspray gave a calculated value of 55 ppm DME and 88 ppm LPG for the stylist over an 8 h working period.

Simulated consumer exposure to propellant HCFC 22 (chlorodifluoromethane) in aerosol personal products.

Summary The potential human exposure to the aerosol propellant HCFC 22 (chlorodifluoromethane) arising from its use in personal products has been assessed. HCFC 22 concentrations were measured in the 'breathing zone' of an experimental manikin and an 'accompanying child' designed to simulate human use of hairsprays, body sprays and antiperspirants in a closed room. Results were expressed as the 10-min time-weighted average concentration in the air (TWA 10) and as the peak concentration in the 'breathing zone' of the 'user'. Following a 10-s use of hairspray containing approximately 20-40% HCFC 22, TWA10 values for an adult user and child were 64-116 ppm and 44-100 ppm, respectively. Use of an aerosol body spray containing 20-65% HCFC 22 for 5-20 s gave rise to TWA10 values of 32-411 ppm for an adult user and 20-395 ppm for a child. A 4-s use of an antiperspirant containing approximately 20-40% HCFC 22 sprayed at a distance of 10-30 cm from the breathing zone of the adult user generated TWA 10 values in the range of 14-34 ppm for both the adult user and child. Opening the door of the room prior to hairspray and antiperspirant spraying slightly reduced these TWA 10 values. The peak values recorded in these studies for the adult user were 208 ppm for hairspray, 1415 ppm for body sprays and 82 ppm for antiperspirants.

Acquired ichthyosis and impaired dermal lipogenesis in Hodgkin's disease.

Epidermal lipid biosynthesis was normal in patients with mild ichthyosis due to Hodgkin's disease, but greatly reduced in one patient with severe ichthyosis. Dermal (sebaceous) lipid synthesis was decreased in all patients with Hodgkin's disease, whether or not they had ichthyosis, and was greatly reduced in the patient with severe ichthyosis. Neither the mechanism nor the possible relationship between the dermal and epidermal changes is understood.

Trimethylaminuria: the use of choline as an aid to diagnosis.

Trimethylamine metabolism can be studied by means of choline loading. The value and some limitations of the method are illustrated by results obtained in normal subjects, a patient with the Fish Odour syndrome and his kindred.

Changes in transepidermal water loss and the composition of epidermal lecithin after applications of pure fatty acid triglycerides to skin of essential fatty acid-deficient rats.

The importance of various unsaturated fatty acid triglycerides to the repair of faulty skin barrier function was studied in essential fatty acid-deficient rats. Following cutaneous application of the pure triglycerides for up to 5 days, the hitherto high rate of transepidermal water loss, characteristic of essential fatty acid deficiency in rats, was reduced by the triglycerides of linoleic and gamma-linolenic acids. Incorporation of the applied fatty acids into the lecithin of the epidermis accompanied these changes in water loss, indicating that cutaneously applied triglycerides may be metabolized by the skin and incorporated into complex lipids. Other fatty acid triglycerides, including alpha-linolenic, dihomo-gamma-linolenic, arachidonic and omega-7-heneicosatrienoic acid, did not lower the rate of transepidermal water loss, although all were incorporated into epidermal structural lipids. The non-essential oleic acid also had no effect upon the rate of transepidermal water loss. These data suggest that of the two main essential fatty acids that occur in skin, linoleic acid and arachidonic acid, the former specifically plays an important role in regulating barrier function whereas the later may have a separate function, such as serving as a precursor of prostaglandins.

The repair of impaired epidermal barrier function in rats by the cutaneous application of linoleic acid.

Epidermal barrier function in rats was experimentally impaired by two separate means, namely, by rendering the animals deficient in essential fatty acids and by evoking a primary cutaneous irritant response by treating with a solution of sodium laurate. Impaired barrier function was manifested by a greatly increased rate of transepidermal water loss. Application to the skin of sunflower seed oil, which is rich in linoleic acid, rapidly restored to normal the abnormally high rates of transepidermal water loss in both experimental cases, and it was shown with the essential fatty acid-deficient rats that there was a concomitant incorporation of linoleic acid of the sunflower seed oil into epidermal lipids. Cutaneous application of olive oil, which is low in linoleic acid but rich in the non-essential oleic acid, did not influence epidermal barrier function. A close relationship of barrier function and essential fatty acids is indicated.