Skin irritation mechanism

Chitosan acetate and lactate salt films have been tested as wound-healing materials. Mechanical, bioadhesive and biological evaluation of the films were carried out. The results were compared to Omiderm . Chitosan lactate exhibited a lower tensile strength, however, it was more flexible and bioadhesive than chitosan acetate. Chitosan lactate and Omiderm did not cause any allergic reactions in contrast, chitosan acetate produced skin irritation clearly due to the anion. Nevertheless, no sign of toxicity was encountered when the extracts of three preparations were administered parenterally [244]. 

Patrick E, Maibach HI, Burkhalter A. 1985. Mechanisms of chemically induced skin irritation. I. Studies of time course, dose response, and components of inflammation in the laboratory mouse. Toxicol Appl Pharmacol 81 476-490. 

Toxicology. Wood dust exposure may cause eye and skin irritation, respiratory effects, and hardwood nasal cancer. Irritation of the skin and eyes resulting ftom contact with wood dust is relatively common and may result ftom mechanical action (e.g., irritation caused by bristles and splinters), chemical irritation, sensitization, or a combination of these factors. ... 

The state of the art is a combination of linear low-density polyethylene (PE-LLD) with hmestone for diaper back sheets. By biaxial orientation, the balance of mechanical permeability requirements can be obtained. Because of its PE-like characteristics Ecoflex is a good choice for a biodegradable back sheet. Ecoflex provides a good regulatory basis for these applications because of the positive results of the primary skin irritation test according to OECD 404, as well as the guinea pig test according to OECD 406. 

Conduct research into the mechanisms involved in skin irritation across a range of different chemical classes both in vitro and in man, using proteomics, genomics, and metabonomics. 

The test article is administered as solution or suspension to the back of six albino rabbits. The test material is administered to two sites onto the rabbits skin where the skin has to be clipped. On one site the skin remains intact, on the other the skin is mechanically abraded in order to remove the outer layer of the skin, the stratum comeum. The clipped areas should have a surface of about 1 square inch onto which the test material is administered. The dose level to be administered to the skin is 0,5 ml in case of liquids or 0,5 g in case of solid materials. The treated skin areas are covered with surgical gaze and fixed with a non-irritation tape. A second layer consisting of an occlusive material is wrapped over the entire trunk of the rabbits in order to avoid or retard the evaporation of the test material from the treated skin areas. After 24 hours, the wrapping is removed from the animals and the treated skin sites are evaluated for erythema and oedema, the classical signs of inflammation. 

Mechanisms of Keratinocyte Mediation of Skin Irritation/lnflammation... 

Exposure to glass fibers sometimes causes irritation of the skin and, less frequently, irritation of the eyes, nose, or throat. This is not an allergic reaction, but simply a mechanical irritation. Skin irritation typically is experienced by individuals who are newly exposed to fibrous glass and it usually diminishes after several days of exposure. Good personal and industrial hygiene practices minimize the amount of discomfort experienced. 

Skin irritation caused by skin stripping at the removal of PSA When the adhesive strength between the adhesive and the outmost stratum corneum cell is stronger than the intercellular binding force between stratum corneum cells, the outmost stratum corneum cells will be transferred from the skin to the adhesive when PSA is peeled from skin. This mechanical skin damage also causes pain and skin irritation. 

Basketter D, Darlenski R, Fluhr JW. Skin irritation and sensitization mechanisms and new approaches for risk assessment. Skin Pharmacol Physiol. 2008 21 191-202. 

Stoddard Solvent is a slight to severe skin irritant depending on the exposure condition and duration. This is related to the defatting properties of the solvent. Little is known regarding the specific mechanisms of action for systemic toxicity to Stoddard Solvent. Its effect on the nervous system at high exposure levels may be due to its general solvent properties and anesthetic effect of hydrocarbons in general. 

As discussed in the Identification of Data Needs section for intermediate-duration exposure, additional animal studies comparing exposure-response relationships for skin irritation for acute- intermediate- and chronic-exposure durations would be useful in estimating concentrations of formaldehyde solutions that will not damage the skin with repeated exposures. Although no comprehensive toxicity studies in animals were located regarding chronic dermal exposure, understanding of formaldehyde toxicokinetics and mechanism of action suggests that distant-site toxicity is not a concern at environmentally or occupationally relevant dermal exposure levels. 

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