Membrane mucous

Selenium is an essential element and is beneficial at low concentrations, serving as an antioxidant. Lack of selenium affects thyroid function, and selenium deficiencies have been linked to Keshan Disease (34). Selenium at high levels, however, is toxic. Hydrogen selenide (which is used in semiconductor manufacturing) is extremely toxic, affecting the mucous membranes and respiratory system. However, the toxicity of most organ oselenium compounds used as donor compounds for organic semiconductors is not weU studied. 

If acetal resins are processed at temperatures substantially above those recommended for the particular grade, minor amounts of formaldehyde may be Hberated. Formaldehyde (qv) is a colorless, lacrimatory gas with a pungent odor and is intensely irritating to mucous membranes. The human nose is sensitive to concentrations in the range of 0.1 to 0.5 ppm. The current threshold limit value for formaldehyde is 1 ppm. 

With respect to acute toxicity, based on lethaHty in rats or rabbits, acryhc monomers are slightly to moderately toxic. Mucous membranes of the eyes, nose, throat, and gastrointestinal tract are particularly sensitive to irritation. Acrylates can produce a range of eye and skin irritations from slight to corrosive depending on the monomer. 

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. 

Adipic acid is an irritant to the mucous membranes. In case of contact with the eyes, they should be flushed with water. It emits acrid smoke and fumes on heating to decomposition. It can react with oxidizing materials, and the dust can explode ia admixture with air (see Table 3). Fires may be extinguished with water, CO2, foam, or dry chemicals. 

Chlorine gas is a respiratory irritant and is readily detectable at concentrations of <1 ppm in air because of its penetrating odor. Chlorine gas, after several hours of exposure, causes mild irritation of the eyes and of the mucous membrane of the respiratory tract. At high concentrations and in extreme situations, increased difficulty in breathing can result in death through suffocation. The physiological response to various levels of chlorine gas is given in Table 19. 

Gustation. A taste sense, the receptors of which He in the mucous membrane covering the tongue, and the stimuli for which consist of certain soluble chemicals, eg, salts, acid, and sugar. 

The inhalation toxicity of NF on animals has been studied extensively (37—40). These studies provide the basis of emergency exposure limits (EEL) that have been proposed for NE. The NAS—NRC Committee on Toxicology recommends that the EEL for NE be 10 min at 2250 ppm, 30 min at 750 ppm, and 60 min at 375 ppm. Gaseous NE is considered to be innocuous to the skin and a minor irritant to the eyes and mucous membranes. NE does give a weakly positive metabotically activated Ames test but only at concentrations greater than 2% or 10 times the 10 minute EEL. 

Dorex is very toxic (see Table 2) and must be handled with extreme care. Because it may produce severe dermatitis on moist skin, it is difficult to use in hot, humid climates inhalation of the dust or spray may irritate the mucous membranes. Whereas symptoms may include a flushed face, tachycardia, headache, vertigo, and hypotension, it does not produce the typical cyanide effect. 

The threshold limit value (TLV) for cyclohexane is 300 ppm (1050 mg/m ). With prolonged exposure at 300 ppm and greater, cyclohexane may cause irritation to eyes, mucous membranes, and skin. At high concentrations, it is an anesthetic and narcosis may occur. Because of its relatively low chemical reactivity, toxicological research has not been concentrated on cyclohexane. 

Hydrogen chloride in air is an irritant, severely affecting the eye and the respiratory tract. The inflammation of the upper respiratory tract can cause edema and spasm of the larynx. The vapor in the air, normally absorbed by the upper respiratory mucous membranes, is lethal at concentrations of over 0.1% in air, when exposed for a few minutes. HCl is detectable by odor at 1—5 ppm level and becomes objectionable at 5—10 ppm. The maximum concentration that can be tolerated for an hour is about 0.01% which, even at these levels, causes severe throat irritation. The maximum allowable concentration under normal working conditions has been set at 5 ppm. 

Health and Safety Factors. Like other low molecular weight ketones, MIBK is an anesthetic chemical with no highly cumulative toxicological effects. Inhalation of vapors can irritate mucous membranes. 

Maleic Anhydride. The ACGIH threshold limit value in air for maleic anhydride is 0.25 ppm and the OSHA permissible exposure level (PEL) is also 0.25 ppm (181). Maleic anhydride is a corrosive irritant to eyes, skin, and mucous membranes. Pulmonary edema (collection of fluid in the lungs) can result from airborne exposure. Skin contact should be avoided by the use of mbber gloves. Dust respirators should be used when maleic anhydride dust is present. Maleic anhydride is combustible when exposed to heat or flame and can react vigorously on contact with oxidizers. The material reacts exothermically with water or steam. Violent decompositions of maleic anhydride can be catalyzed at high temperature by strong bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, alkaU metals, and amines). Precaution should be taken during the manufacture and use of maleic anhydride to minimize the presence of basic materials. 

Methanol is not classified as carcinogenic, but can be acutely toxic if ingested 100—250 mL may be fatal or result in blindness. The principal physiological effect is acidosis resulting from oxidation of methanol to formic acid. Methanol is a general irritant to the skin and mucous membranes. Prolonged skin contact with methanol vapor or Hquid can cause dermatitis. Methanol vapor can cause eye and respiratory tract irritation, nausea, headaches, and dizziness. 

LLDPE can present a certain health hazard when it bums, since smoke, fumes, and toxic decomposition products are sometimes formed in the process. Exposure to burning LLDPE can cause irritation of the skin, eyes, and mucous membranes of the nose and throat due to the presence of acrolein and formaldehyde (81). Toxicity of LLDPE pyrolysis products depends on temperature, heating rate, and the sample size (82—84). 

Lithium peroxide is a strong oxidizer and can promote combustion when in contact with combustible materials. It is a powerful irritant to skin, eyes, and mucous membranes (2) protective clothing should be worn when handling lithium peroxide. The LD q has not been deterrnined, and there is no designated threshold limit value (TLV). However, 5 g of many lithium compounds can be fatal. 

No toxicological studies have been reported on the triple salt. However, because of the common confusion of this compound with potassium hydrogen monoperoxosulfate monohydrate, it is possible that the pubHshed descriptions of the toxic properties of this latter compound actually refer to the triple salt. If this is so, then the triple salt must be regarded as toxic and irritating to skin, eyes, and mucous membranes (2). 

Potassium hydrogen monoperoxosulfate monohydrate [14696-73-2] KHSO 20, related to the triple salt, is not made commercially. The crystal stmcture has been determined and some features of its Raman and ir spectra recorded (69). This compound is more stable under x-rays than the triple salt. The 0—0 distance is 0.1460 nm. The dihedral angle of the 0—0 moiety is about 90°, similar to that ia soHd hydrogea peroxide. This compouad is reported as toxic and irritating to eyes, skin, and mucous membranes (2). Although undoubtedly correct, this description probably better relates to the triple salt. 

The three peroxodisulfates are ah. toxic and irritating to skin, eyes, and mucous membranes. Pubhshed toxicity studies are as foUow (28) ... 

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