Subjective irritation

Subjective irritation is believed to be the most common cause of sensitive skin and cosmetic reactions.2 Propylene glycol, butylene glycol, and hydroxy acids are examples of subjective irritants present in modern-day cosmetics.2 12 Alcohol is also capable of causing subjective irritation, but is... 

Before confirming a diagnosis of subjective irritation, patients must be patch tested and open tested to exclude allergic contact dermatitis and contact urticaria, respectively. Subclinical contact urticaria, in particular, mimics sensory irritation. 

Subjective and objective irritation must be mentioned in this context because they constitute the major differential diagnosis, which emphasizes the importance of patch testing. Subjective irritation refers to invisible changes burning, stinging, itching, and discomfort (Mathias and Maibach 1978). 

It has been suggested that agents causing subjective irritation act via a similar mechanism, because no visible inflammation is present. 

Subjective symptoms are always present. Itching, stinging and burning sensations are the usual complaints of many patients, with or without objective signs. In particular, facial complaints are not often accompanied by detectable lesions they correspond to the so-called subjective irritant dermatitis . The eyelids, cheeks, nasal folds and neck are commonly involved. Subjective symptoms may occur on covered parts of the body, mainly in the flexures (axillae, groins, cubital and/or popliteal fossae) but also on the extensor aspects of the limbs or on the trunk. 

When dispersed as a dust, adipic acid is subject to normal dust explosion hazards. See Table 3 for ignition properties of such dust—air mixtures. The material is an irritant, especially upon contact with the mucous membranes. Thus protective goggles or face shields should be worn when handling the material. Prolonged contact with the skin should also be avoided. Eye wash fountains, showers, and washing faciUties should be provided in work areas. However, MSDS Sheet400 (5) reports that no acute or chronic effects have been observed. 

Health and Safety Factors. Boron trifluoride is primarily a pulmonary irritant. The toxicity of the gas to humans has not been reported (58), but laboratory tests on animals gave results ranging from an increased pneumonitis to death. The TLV is 1 ppm (59,60). Inhalation toxicity studies in rats have shown that exposure to BF at 17 mg/m resulted in renal toxicity, whereas exposure at 6 mg/m did not result in a toxic response (61). Prolonged inhalation produced dental fluorosis (62). High concentrations bum the skin similarly to acids such as HBF and, if the skin is subject to prolonged exposure, the treatment should be the same as for fluoride exposure and hypocalcemia. No chronic effects have been observed in workers exposed to small quantities of the gas at frequent intervals over a period of years. 

Health and Safety Factors. Results of acute oral toxicity studies of 2-pyrrohdinone on white rats and guinea pigs show the LD q to be 6.5 ml,/kg. Skin patch tests on 200 human subjects indicate that 2-pyrrohdinone is a skin kritant, but there is no indication of sensitising action. It is a mild eye irritant (79). 

Melamine ia a skin test on rabbits produced neither local irritation nor systemic toxicity. As a 10% solution ia methylceUulose, it caused no irritation ia the eyes of rabbits. Human subjects were given patch tests with melamine. No evidence of either primary irritation or sensitization was found. Such results suggest that melamine crystal may be handled ia ordinary iadustrial use without special hygienic precautions. 

Skin irritation potential is assessed by patch tests. More serious than simple irritation is the potential of a product to cause sensiti2ation, ie, to cause a subject to become allergic to even very small amounts of the product. 

Skin tolerance was tested on rabbits. A 1 % alkanesulfonate solution applied five times did not produce any irritation on the rabbits skin. The same results were obtained by the closed patch test carried out with human test subjects in a hospital. The good dermatological properties were also confirmed by the Polano test (arm immersion test). 

The study will commence with the administration of low doses, as judged from the non-clinical data. As the study progresses - and provided that there are no indications that it is unsafe to do so - the dosage levels may be increased past the anticipated therapeutic range. Subjects are closely monitored for changes in vital signs (blood pressure, heart rate, body temperature, etc.) and the emergence of any adverse side effects (nausea, drowsiness, pain, headache, irritability, hair loss, etc.). 

Dermal Effects. Humans that were experimentally exposed to 200 ppm of trichloroethylene vapor for 7 hours experienced dry throats (40% of the subjects), begiiming after 30 minutes (Stewart et al. 1970). The subjects experiencing these symptoms did not experience them when exposed in the same manner on 5 other consecutive days. These effects are presumed to be due to direct contact with the vapor. Skin irritation and rashes have resulted from occupational exposure to trichloroethylene (Bauer and Rabens 1974 El Ghawabi et al. 1973). The dermal effects are usually the consequence of direct skin contact with concentrated solutions, but occupational exposure also involves vapor contact. Adverse effects have not been reported from exposure to dilute aqueous solutions. 

Effects noted in study and corresponding doses Mild subjective neurological effects (eye and throat irritation, headache, fatigue, drowsiness) were reported at 200 ppm (LOAEL). No objective effects, as measured by dexterity and coordination tests, were seen. However, 50% of the subjects reported that the neurobehavioral tests required greater mental effort for them to perform. 

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