Skin sensitization definition

Despite the fact that a definite decrease in IgE antibody levels and IgE-mediated skin sensitivity normally requires several years of SIT, most patients are protected against bee stings already at an early stage of bee venom-SIT. The reason for this is that effector cells of allergic inflammation, such as mast cells, basophils and eosinophils. 

In the OECD test guideline for skin sensitization (OECD TG 406), the following definition is given Skin sensitization (allergic contact dermatitis) is an immunologically mediated cutaneous reaction to a substance. In the human, the responses may be characterized by pruritis, erythema, edema, papules, vesicles, bullae, or a combination of these. In other species, the reactions may differ and only erythema and edema may be seen. ... 

This definition is also used by the US-EPA and by the EU in their respective guidelines for skin sensitization (OPPTS 870.2600 Skin Sensitization and B.6. Skin Sensitization). 

Sensitive skin is largely believed to be a widespread phenomenon. Epidemiological studies have shown that the incidence of self-reported skin sensitivity is 51.4% in women and 38.2% in men. Studies also show that 10% of women and 5.8% of men consider themselves to have very sensitive skin.3 However, consumer-perceived cutaneous reactions are usually scientifically unconfirmed self-assessment is not an accurate parameter. Furthermore, estimates of the prevalence or incidence of sensitive skin are problematic as the term sensitive skin lacks a consistent definition. 

Contact sensitizer means a substance that will induce an allergic response following skin contact. The definition for contact sensitizer is equivalent to skin sensitizer ... 

The TGD (EC 2003), Chapter 3.8, on sensitization gives definitions of skin and respiratory sensitization, and provides advice on the data to be used in the effects assessment, evaluation on the available data, and assessment of the dose-response relationship to be used in the EU-specific risk assessments. 

Morizot, F., Le Fur, I., and Tschachler, E., Sensitive skin, definitions, prevalence and possible causes, Cosmet. Toiletries, 113, 59, 1998. 

The results of the latter two studies described contradict earlier data. Up to this point, an elevated TEWL had been the most widely accepted biophysiological parameter associated with sensitive skin, due to impairment of the skin barrier function or composition. That further studies are imperative to create a consistent and objective operational definition for sensitive skin is affirmed by these conflicting results. 

Sensitive skin is not a single entity, but a heterogeneous syndrome, puzzling both consumer and clinician alike. The definition remains obscure, and so it follows that prevalence and pathophysiology are as yet undetermined. Innovative skin bioengineering techniques have opened up new avenues for... 

In humans the major and consistent effect is on the skin. Exposed people suffer from a severe form of acne, known as chloracne, after exposure to dioxin. Changes in the immune system have also been detected in the children exposed at Seveso in Italy and workers exposed at the Coalite plant in the UK. The latter had reduced levels of some immunoglobulins. There is no definitive evidence as to whether humans are more or less sensitive to dioxin than other mammals but the weight of evidence would suggest that they are less sensitive than many. 

Ammonia has an odor threshold ranging from 1 to 5 ppm. Exposures between 20 and 25 ppm can cause complaints and discomfort in some workers unaccustomed to ammonia exposure but have little effect on pulmonary function or odor sensitivity. Concentrations of 100 ppm caused definite irritation of the respiratory tract and eyes, and exposures at 250 ppm ammonia are bearable for 30-60 min. Severe irritation of the respiratory tract, skin, and eyes has been observed following ammonia exposures ranging from 400 to 700 ppm. Exposure to 2500-4500 ppm ammonia can be fatal within 30 min. Immediate fatalities appear to be the result of airway obstruction, particularly laryngeal edema and glottic spasm, while infections and other secondary complications appear to be the cause of fatality among those who survive for several days to weeks. 

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