Respiratory Penetration

Gases/vapors must get into solution in the thin fluid film in the alveoli for systemic absorption to occur. For this reason doses are often a measurement of partial pressures, which is important for gases/vapors. 

Airborne toxicants can be simplified to two general types of compounds, namely gases and aerosols. Compounds such as gases, solvents, and vapors are subject to gas laws and are carried easily to alveolar air. Much of our understanding of xenobiotic behavior is with anesthetics. Compounds such as aerosols, particulates, and fumes are not subject to gas laws because they are in particulate form. 

There are several other important factors that can determine whether the gas will be absorbed in blood and then transported from the blood to the perfused tissue. The concentration of the gas in inspired air influences gas tension, and partial pressure can be increased by overventilation. In gas anesthesiology we know that the effects of 

While gases are more likely to travel freely through the entire respiratory tract to the alveoli, passage of aerosols and particles will be affected by the upper respiratory tract, which can act as an effective filter to prevent particulate matter from reaching the alveoli. Mucous traps particles to prevent entry to alveoli, and the mucociliary apparatus in the trachea traps and pushes particles up the trachea to the esophagus where they are swallowed and possibly absorbed in the GI tract. 

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Iakovlev, A. (1958). The importance of antitoxic immunity for the defence of the body in respiratory penetration by bacterial toxins. I. Role of passive immunity in the defence of the body against respiratory disease caused by Clostridium botulinum toxins. J. Microbiol. Epidemiol. Immunobiol. 29 904-9. 

The use of metered-dose valves in aerosol medical appHcations permits an exact dosage of an active dmg to be deHvered to the respiratory system where it can act locally or be systemicaHy absorbed. For example, inhalers prescribed for asthmatics produce a fine mist that can penetrate into the bronchial tubes (see Antiasthmatic agents). 

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. 

The filariform larva found in moist soils may be either ingested or penetrate the skin of its host. It is then carried through the circulatory system to the lungs and migrates up the respiratory tree into the digestive tract. The worms feed on intestinal tissue and blood. Some worms may persist in humans as long as nine years. Infestations cause cutaneous reactions, pulmonary lesions, intestinal ulcerations, and anemia. 

The primary routes of entry for animal exposure to chromium compounds are inhalation, ingestion, and, for hexavalent compounds, skin penetration. This last route is more important in industrial exposures. Most hexavalent chromium compounds are readily absorbed, are more soluble than trivalent chromium in the pH range 5 to 7, and react with cell membranes. Although hexavalent compounds are more toxic than those of Cr(III), an overexposure to compounds of either oxidation state may lead to inflammation and irritation of the eyes, skin, and the mucous membranes associated with the respiratory and gastrointestinal tracts. Skin ulcers and perforations of nasal septa have been observed in some industrial workers after prolonged exposure to certain hexavalent chromium compounds (108—110), ie, to chromic acid mist or sodium and potassium dichromate. 

Tlie respiratory system is tlie main target organ for vapour, gas or mist. Readily-soluble cheirticals, e.g. chlorine or phosgene, attack the upper respiratory tract less soluble gases, e.g. oxides of nitrogen, penetrate more deeply into the conducting airways and, in some cases, may cause pulmonary oedema, often after a time delay. 

Studies on the particulate distributions from compressed natural gas (CNG) or diesel-fuelled engines with diesel oxidation catalyst (DOC) or partial diesel particle filter (pDPF) have also been performed. The results obtained are used as data for the model, to study the particle penetration into the human respiratory tracts. As a result, the number distribution of particles in different parts of lungs can be modeled [99-101]. Understanding the particle formation and their effects and finding the methods to ehminate the formed particulates from exhaust gas contribute to a cleaner urban environment and thus to a better quality of life. 

Diazepam Being extremely lipophilic, diazepam penetrates quickly into the CNS, but can rapidly redistribute into body fat and muscle. This results in a faster decline in CNS levels and early recurrence of seizures. It is dosed at 5 to 10 mg (or 0.15 mg/kg) and infused no faster than 5 mg/minute. Repeated doses can be given every 5 minutes until seizure activity stops or toxicities are seen (e.g., respiratory depression). Diazepam can also be administered as a rectal suppository, making it possible for non-medical personnel to provide rapid therapy for seizures that develop at home or in public areas.11 The adult dose is 10 mg given rectally and this dose may be repeated once if necessary. Diazepam is erratically absorbed via the intramuscular route therefore, IM administration is not recommended. 

PM2.5 - Particulate material less than 2.5 xm diameter forms in the same way as PM 0, but it can penetrate deeper into the respiratory system than PMio. 

Penetrating through the respiratory and intestinal tracts, and the integument, pesticides undergo a dual transformation [6] both chemical transformations (oxidation, reduction, hydrolysis), and the formation of complex compounds with biochemical components in the body. 

Urticants have a penetrating and disagreeable odor detectable at very low concentrations. Even minimal exposure causes immediate irritation and pain of the eyes, nose, mucous membranes, respiratory system, and skin. Urticants pose a significant percutaneous hazard and are absorbed through the skin within seconds. 

White, granular, or crystalline deliquescent solid that is odorless when dry but has a faint odor like almond when wet. This material is hazardous through inhalation, skin absorption, penetration through broken skin, and ingestion, and produces local skin/eye impacts. It causes irritation of the eyes and skin, asphyxia, lassitude, headache, confusion, nausea, vomiting, increased respiratory rate, slow gasping respiration, thyroid, and blood changes. 

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