Overexposure

DMAC is capable of pioducing systemic injury when repeatedly inhaled or absorbed through the skin. Symptoms of overexposure are nausea, headache. 

Full eye protection should be worn whenever handling acryhc monomers contact lenses must never be worn. Prolonged exposure to Hquid or vapor can result in permanent eye damage or blindness. Excessive exposure to vapors causes nose and throat irritation, headaches, nausea, vomiting, and dizziness or drowsiness (solvent narcosis). Overexposure may cause central nervous system depression. Both proper respiratory protection and good ventilation are necessary wherever the possibiHty of high vapor concentration arises. 

Effects of repeated ethylene glycol peroral overexposure in treated rats and mice can result in kidney, Hver, and nervous system damage. The most sensitive indicators of ethylene glycol toxicity are disturbances in acid—base balance and nephrotoxic (kidney) effects. Effects of repeated chronic peroral overexposure of diethylene glycol in treated rats result in kidney and Hver damage (48). 

How Many Samples. A first step in deciding how many samples to collect is to divide what constitutes an overexposure by how much or how often an exposure can go over the exposure criteria limit before it is considered important. Given this quantification of importance it is then possible to calculate, using an assumed variabihty, how many samples are required to demonstrate just the significance of an important difference if one exists (5). This is the minimum number of samples required for each hypothesis test, but more samples are usually collected. In the usual tolerance limit type of testing where the criteria is not more than some fraction of predicted exceedances at some confidence level, increasing the number of samples does not increase confidence as much as in tests of means. Thus it works out that the incremental benefit above about seven samples is small. 

Fig. 3. Confidence limits for exposure levels. A, noncompliance B, possible overexposure C, compliance. STD is the standard value, LCL and UCL represent lower and upper confidence levels, between which it is 95% certain that the tme exposure Hes, and and correspond to two separate...

Options. Traditional control options for overexposure are material substitution, process change, containment, enclosure, isolation, source reduction, ventilation, provide personal protection, change work practices, and improve housekeeping. A simple way of looking at selection of control options is to find the cheapest option that results in the desired amount of exposure reduction. It is not actually that simple, however, because the various options differ in ways other than cost and degree of control. Some of the other factors to consider in selection of control options are operabiUty, rehabiUty, and acceptabihty. 

AH x-ray equipment must be periodically inspected and the output monitored and caUbrated to minimize the chance of accidental overexposure. Another concern involves radiation accumulation by medical personnel operating x-ray equipment. Although the dose to any one patient may be low, the accumulated dose to a clinician performing multiple exams each day over the course of a year is great. Therefore, personnel working with x-ray equipment must take precautions constandy to minimize and monitor exposure. Lead aprons and film badges are used to minimize exposure and to monitor accumulated dose, respectively. 

Nickel carbonyl should be used in totally enclosed systems or under good local exhaust. Plants and laboratories where nickel carbonyl is used should make use of air-monitoring devices, alarms should be present in case of accidental leakage, and appropriate personal respiratory protective devices should be readily available for emergency uses. Monitoring of urinary nickel levels is useful to help determine the severity of exposure and identify appropriate treatment measures. Some large-scale users of nickel carbonyl maintain a supply of sodium diethyldithiocarbamate, or Antabuse, a therapeutic agent, on hand for use in case of overexposure. 

Extreme caution must be taken to prevent the possibility of fire when using flammable removers. Extra care must be taken when stripping on location to secure the area of ignition sources. When used on lacquer finishes, the dissolved finish and remover combined are extremely flammable. Natural mbber, neoprene, or other gloves suitable for use with the remover formula must be worn. The effect of skin contact with the remover is limited because there is immediate irritation and discomfort. Canister respirators are available for most petroleum and oxygenate remover solvents. Symptoms of long-term overexposure should be compared to symptoms of the major ingredients in the formula. 

Health and Safety Factors. Phloroglucinol has low toxicity by ingestion. Prolonged severe overexposure may dismpt the thyroid function. High dust concentration may cause respiratory irritation the product is irritating to eyes and skin. Toxicity data include LD q oral (rat) = 5800 mg/kg ... 

Acute effects of overexposure are as follows. Exposure to dust may cause mechanical irritation of the eye. PPS is essentially nonirritating to the skin, although freshly molded material may occasionally cause dermatitis. Inhalation of PPS dust may cause mechanical irritation to mucous membranes of nose, throat, and upper respiratory tract. 

Subchronic effects of overexposure have been studied in feeding tests of PPS powder at dietary levels of up to 5%. No detrimental effects in laboratory animals were observed (157). 

NIOSH/MSHA-approved respiratory protection devices should be used. For skin protection, use of protective garments and gloves of Viton, Nitrile, or PVA constmction should be made. The acute effects of overexposure to styrene are shown in Table 6 (74). 

Fig. 10. Two materials, A and B, have statistically similar LD q values but, because of differences ia the slopes of the dose—mortaUty regression lines, there are significant differences ia mortaUty at the LD q and LD jq levels. Material A is likely to present problems with acute overexposure to large numbers of iadividuals ia an exposed population when lethal levels are reached. With Material B, because of the shallow slope, problems may be encountered at low...

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 ... 

Antimony is not known to cause cancer, birth defects, or affect reproduction in humans. However, antimony has been shown to cause lung cancer in laboratory animals that inhaled antimony-containing dusts and prolonged exposure to antimony can cause irritation of the eyes, skin, lungs, and stomach, in the form of vomiting and diarrhea. Heart problems can also result from overexposure to antimony (33). 

An acute lethal dose (LC q) for vapor exposure to 1,1,2-trichloroethane in the rat is 2000 ppm for a 4-h exposure. The same lethal effect occurs at 18,000 ppm vapor during 3 h exposure to 1,1,1-trichloroethane. The oral LD q for 1,1,2-trichloroethane in rats is 0.1—0.2 g/kg, classifying it as moderately toxic (109). Liver and kidney damage occurs at even lower dosages. Skin adsorption is a possible route of overexposure. 

Victims of overexposure to trichloroethylene should be removed to fresh air, and medical attention should be obtained immediately. A self-contained positive pressure breathing device should be used wherever high vapor concentrations are expected, eg, when cleaning up spills or when accidental releases occur. 

Overexposure to tetrachloroethylene by inhalation affects the central nervous system and the Hver. Dizziness, headache, confusion, nausea, and eye and mucous tissue irritation occur during prolonged exposure to vapor concentrations of 200 ppm (15). These effects are intensified and include incoordination and dmnkenness at concentrations in excess of 600 ppm. At concentrations in excess of 1000 ppm the anesthetic and respiratory depression effects can cause unconsciousness and death. A single, brief exposure to concentrations above 6000 ppm can be immediately dangerous to life. Reversible changes to the Hver have been reported foUowing prolonged exposures to concentrations in excess of 200 ppm (16—22). Alcohol consumed before or after exposure may increase adverse effects. 

AHyl chloride has a disagreeable, pungent odor. The odor threshold has been estimated at approximately 3—6 ppm (51). Olfactory detection of odor is thus not an adequate warning of overexposure. 

Benzyl chloride is a severely irritating Hquid and causes damage to the eyes, skin, and respiratory tract including pulmonary edema. Other possible effects of overexposure to benzyl chloride are CNS depression, Hver, and heart damage. Table 3 Hsts some exposure limits. 

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