Absorption through

Whereas the emission spectrum of the hydrogen atom shows only one series, the Balmer series (see Figure 1.1), in the visible region the alkali metals show at least three. The spectra can be excited in a discharge lamp containing a sample of the appropriate metal. One series was called the principal series because it could also be observed in absorption through a column of the vapour. The other two were called sharp and diffuse because of their general appearance. A part of a fourth series, called the fundamental series, can sometimes be observed. 

The cured 2-cyanoacryhc ester polymers are relatively nontoxic. Oral doses of 6400 mg/kg failed to kill laboratory rats. Mild skin irritation was observed with guinea pigs, but there was no evidence of sensitization or absorption through the skin (15). 

DHBs are rapidly absorbed through the digestive tract. Their absorption through skin is low in aqueous solution but may be increased in suitable... 

Mode of Action. DDT and its analogues specifically affect the peripheral sense organs of insects and produce violent trains of afferent impulses that result in hyperactivity, convulsions, and paralysis. Death results from metaboHc exhaustion and the production of an endogenous neurotoxin. The very high lipophilic nature of these compounds faciUtates absorption through the insect cuticle and penetration to the nerve tissue. The specific site of action is thought to be the sodium channels of the axon, through inhibition of Ca " ATPase. 

Health and Safety Factors. Malononitrile is usually available as a soHdifted melt in plastic-Hned dmms. Remelting has to be done carefully because spontaneous decomposition can occur at elevated temperatures, particularly above 100°C, in the presence of impurities such as alkaHes, ammonium, and 2inc salts. Melting should be carried out by means of a water bath and only shordy before use. Occupational exposure to malononitrile mainly occurs by inhalation of vapors and absorption through the skin. Malononitrile has a recommended workplace exposure limit of 8 mg/m, an LD q (oral, rats) of 13.9 mg/kg, and is classified as slight irritant (skin irritation, rabbits). Transport classification RID/ADR 61, IMDG-Code 6.1, lATA/ICAO 6.1. 

Toxicity. Inorganic mercury compounds, aryl mercury compounds, and alkoxy mercurials are generahy considered to be quite similar in their toxicity. Alkyl mercury compounds are considered to be substantiahy more toxic and hazardous. Mercury and its compounds can be absorbed by ingestion, absorption through the skin, or by inhalation of the vapor. The metal itself, however, rarely produces any harmful effects when ingested (16). 

Strong acids and strong alkaUes can severely bum the skin, chromium compounds can produce skin rashes, and repeated exposure to solvents causes removal of natural oils from the skin. Infection is always a concern for damaged skin. Absorption through the skin is possible for materials that are appreciably soluble iu both water and oil, eg, nitrobenzene, aniline, and tetraethyllead. Other materials can be absorbed if first dissolved iu extremely good solvents, eg, dimethyl sulfoxide. Subcutaneous iujection can occur accidentally by direct exposure of the circulatory system to a chemical by means of a cut or scratch or iuadvertent penetration of the skin with a hypodermic needle. 

Monoethan olamine and monoisopropan olamine may be moderately toxic by absorption through the skin. The other amines are low in toxicity by this route and are not likely to be absorbed in acutely toxic amounts. In the event of skin contact, clothing and shoes should be removed promptly, and the skin thoroughly washed with water. Contaminated clothing should be thoroughly cleaned before reuse shoes and leather products should be discarded. 

Toxicology. Isoquinoline is a poison when ingested or injected intraperitoneally. Even in cases of skin contact it is moderately toxic. As in the case of quinoline, its vapors are irritating to the eyes, nose, and throat. Exposure causes headaches, dizziness, and nausea. Rapid absorption through the skin makes it a dangerous chemical. Its toxicity is oral LD q (i t)> mg/kg, and dermal LD q (rabbit), 590 mg/kg (65,66,182,183). 

Elemental tellurium and the stable teUurides of heavy nonferrous metals are relatively inert and do not represent a significant health hazard (43—47). Other, more reactive teUurides, including soluble and volatile teUurium compounds such as hydrogen teUuride [7783-09-7] teUurium hexafluoride [7783-80-4] and alkyl teUurides, should be handled with caution. Some of these materials can enter the body by absorption through the skin or by inhalation and ingestion of dust or fumes. No serious consequences or deaths have been reported in workers exposed to teUurium and its compounds in industry (48). 

Vinyl acetate has moderate acute toxicity if ingested. The LD q for oral ingestion in rats is 2.9 g/kg body weight for absorption through the skin, the LD q in rats is more than 5 mL/kg in 24 h. First-aid procedures to be followed in the event of overexposure to vinyl acetate are as foUow ... 

Methylene chloride, appHed to both intact and abraded skin of rabbits in doses as large as 0.5 g/kg body weight per day, five times per week, for a period of 90 days, caused no apparent adverse effects. Absorption through the skin is not usually a ha2ard when good working practices are followed. 

In general, all of the chlorobenzenes are less toxic than benzene. Liquid chlorobenzenes produce mild to moderate irritation upon skin contact. Continued contact may cause roughness or a mild bum. SoHds cause only mild irritation. Absorption through the skin is slow. Consequently, with short-time exposure over a limited area, no significant quantities enter the body. 

Permeation enhancers are used to improve absorption through the gastric mucosa. Eor example, oral dehvery of insulin (mol wt = 6000) has been reported from a water-in-oH- emulsion containing lecithin, nonesterified fatty acids, cholesterol [57-88-5], and the protease inhibitor aprotinin [9087-70-1] (23). 

Carcinogenicity of DGEBPA or DGEBPA-based resins, as measured by topical appHcation, has not been shown by a majority of the studies (45). Advanced DGEBPA resins exhibit low systemic toxicity either by dermal or oral routes and inhalation of these resins is unlikely because of low volatihty. The acute oral LD q in rats has been reported to be >2000 mg/kg (46). Acute dermal studies show these materials have alow potential for absorption through the skin in acutely toxic amounts. No evidence of carcinogenicity has been found in animals or humans for advanced DGEBPA resins (47,48). 

Compounds in animal diets can exert their effects in the gastrointestinal tract or after absorption through the gut epithelial tissue into the bloodstream, or both. On some occasions the administered compounds may be applied topically (Table 1). 

The toxicity of a substance is its capacity to cause injury once inside the body. The main modes of entry into the body by chemicals in industry are inhalation, ingestion and absorption through the skin. Gases, vapours, mists, dusts, fumes and aerosols can be inhaled and they can also affect the skin, eyes and mucous membranes. Ingestion is rare although possible as a result of poor personal hygiene, subconscious hand-to-mouth contact, or accidents. The skin can be affected directly by contact with the chemicals, even when intact, but its permeability to certain substances also offers a route into the body. Chemicals accorded a skin notation in the list of Occupational Exposure Limits (see Table 5.12) are listed in Table 5.2. Exposure may also arise via skin lesions. 

Polymeric ethyl cyanoacrylate exhibits very low toxicity properties. In tests with laboratory rats, oral administration of 6400 mg/kg of the polymer failed to harm the test animals. Some skin irritation did occur in tests on guinea pigs, but skin sensitization or absorption through the skin was not observed [45]. 

Enhancing the Profitability of Lean Oil Absorption Through Simulation, GasTIPS , Fail 1996, Volume 2, Number 3, p.38... 

There arc four pathways for substances to enter the body —Absorption through contact with the skin and eyes —Inhalation —Ingestion —Injection/puncture... 

Route of entry Path by which toxins and other substances may enter the human body. These include inhalation, ingestion, and absorption through the skin. Less common routes include injection and absorption through moist surfaces surrounding the eyes and ear canal. 

Skin notation The word skin included as part of an exposure limit. It is used for those substances for which absorption through the skin is considered to be a significant route of entry into the body. 

Toxicity is defined as the quality, state, or degree of being toxic or poisonous. Some liquids contain chemicals that are a serious toxic hazard. These toxic or poisonous chemicals may enter the body through inhalation, by absorption through the skin, or through the eyes or the mouth. The result is sickness and, in some cases, death. Manufacturers of hydraulic liquids strive to produce suitable liquids that contain no toxic chemicals and, as a result, most hydraulic liquids are free of harmful chemicals. Some fire-resistant liquids are toxic, and suitable protection and care in handling must be provided. 

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