Direct exposure

Direct-exposure probe. Provides for insertion of a sample on an exposed surface, such as a flat surface or a wire, into (rather than up to the entrance of) the ion source of a mass spectrometer. 

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. 

Monolithic refractory coatings have been applied to metallic components in furnaces for fuel ash corrosion control. Results have been less than satisfactory because of the large thermal expansion mismatch between the metal and refractory. Failure usually occurs upon thermal cycling which causes cracking, eventual spalling of the refractory, and direct exposure of the metal to the effects of the fuel ash. 

The task analysis is performed on tasks 2, 3, and 4. Tasks 1 and 5 were eliminated from the analysis because they did not involve any direct exposure to hazardous substances (from the initial screening analysis described in Section 2.1). The analysis considers operations 2.1 to 2.5, 3.1 to 3.2 and 4.1 to 4.5 in Figure 5.6. 

Direct exposure to NO can cause respiratory problems. VOCs and NOjj are catalyzed by sunlight to form ground level ozone, often referred to as smog. NO can be generated from either stationary sources or mobile sources. In 1997, the EPA changed the ambient standard for ozone from 0.12 ppm to 0.08 ppm and the applicable test period was increased from I to 8 hours. 

In both cases, tributyltin is included in the table for routes of exposure resulting from contamination of commercial dibutyltin direct exposure from the deliberate use of tributyltin is covered in the appropriate CIC AD (IPCS, 1999b). 

Because of these damaging effects, most uses of lead that involve direct exposure for humans are being phased out. Unleaded gasoline and lead-free paints have replaced two former major commercial uses of lead. Lead has proved to be Indispensable, however, in the lead storage battery, which now provides the major use of this metal. Although leakage from damaged batteries is still a potential hazard, contemporary batteries are manufactured in such a way that human exposure to battery contents is minimized. 

Avoid direct exposure to the sun between the hours of 10 am to 4 pm, when UV rays are most intense. 

Common methods for reducing dermal absorption of diisopropyl methylphosphonate include removing contaminated clothes and washing contacted skin with soap and water (Ellenhom and Barceloux 1988). Following eye contact with diisopropyl methylphosphonate, eyes should be flushed with copious amounts of water. In rabbits, rinsing the eyes immediately after direct exposure to diisopropyl methylphosphonate has been shown to reduce effects (Hart 1976). 

It appears that the decomposition of phenyl azide is significantly accelerated by direct exposure to light. Consequently, during all steps of the procedure in which phenyl azide is present, including that of its removal in vacuo, exposure of the reaction mixtures to direct light must be avoided. 

Environmental exposure (direct). Exposure through air inhalation, soil and dust ingestion, and dermal contact of soil and dust are the principal exposure pathways. Other exposure pathways (e.g., water dermal contact) can be taken into account in some scenarios. Monitoring campaigns or multimedia fate models are used to assess the exposure (see [4]). 

M.P. Colombini, F. Modugno, E. Ribechini, Direct exposure electron ionization mass spectra metry and gas chromatography/mass spectrometry techniques to study organic coatings on archaeological amphorae, Journal of Mass Spectrometry, 40, 675 687 (2005). 

E. Ribechini, F. Modugno, M.P. Colombini, Direct exposure (chemical ionization) mass spectrometry for a rapid characterization of raw and archaeological diterpenoid resinous substances, Microchimica Acta, 162, 405 413 (2008). 

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