Time Weighted Average Concentration


Time-weighted exposure. This is the time-weighted average concentration for a normal 8-hour workday or 40-hour workweek to  [c.259]

Acrylonitrile is categorized as a cancer hazard by OSHA. It has been determined to be carcinogenic to laboratory animals and mutagenic in both mammalian and nonmammalian tests. Genetic transformations and damage have been reported in tissue cultures exposed to acrylonitrile. Animal tests show that it is a reproductive toxicant only at maternally toxic doses. Permissible exposure limits for acrylonitrile in the United States are 2 ppm for an 8-h time-weighted average concentration and 10 ppm as the ceiling concentration for a 15-min period.  [c.185]

Nickel Carbonyl. Nickel carbonyl is an extremely toxic gas. The permissible exposure limit (PEL) in the United States is 1 part per biUion (ppb) in air (127). The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for an 8-h, time-weighted average concentration is 50 ppb (128). Nickel carbonyl may form wherever carbon monoxide and finely divided nickel are brought together. Its occurrence has been suspected but never demonstrated in some industrial operations, eg, welding of nickel alloys.  [c.13]

Phenol fumes are irritating to the eyes, nose, and skin. According to the National Institute for Occupational Safety and Health (NIOSH), exposure to phenol should be controUed so that no employees are exposed to phenol concentrations >20 mg/m, which is a time-weighted average concentration for up to a 10-h work day, 40-h work week. Phenol is very toxic to fish and has a nearly unique property of tainting the taste of fish if present in marine  [c.290]

Threshold limit value—time weighted average. Defined as the maximum time weighted average concentration to which a worker may be exposed repeatedly and without adverse effects for a normal 8 h/d, 40 h/wk period.  [c.318]

Bromine chloride adds to olefins giving bromochloro compounds. BrCl can also displace hydrogen yielding an organic bromide and hydrogen chloride. The use of bromine chloride rather than chlorine as a disinfectant in wastewater treatment has the advantages of maintaining activity over a wider pH range, more rapid disinfection, effectiveness at lower residual concentrations, and lower aquatic toxicity (56). The time-weighted average concentration of bromine chloride should not exceed 0.1 ppm for an 8-h day. Suitable materials of constmction for shipping and storage of BrCl are low carbon steel or nickel, or its alloys, such as Monel (56). Bromine chloride is used as a brominating agent in the preparation of fire-retardant chemicals, pharmaceuticals, high density brominated Hquids, agricultural chemicals, dyes, bleaching agents, and in water treatment, eg, in cooling towers and effluent streams from sewage plants.  [c.292]

The ACGIH recommended maximum time-weighted average concentration in the workplace atmosphere for eight-hour daily exposure is 10 ppm. OSHA has set the permissible exposure level at 2 ppm. It maybe desirable to exclude alcohoHcs, persons with chronic disorders of the Hver, kidneys, and central nervous system, and those with nutritional deficiencies from working with chloroform.  [c.527]

The ACGIH has adopted TLVs of 10 ppm (25 mg/m ) and 1 ppm (4 mg/m ) for EDA and DETA, respectively. Thus, for a normal 8 hr work day, the time weighted average concentrations of EDA and DETA in the air of the workplace should not exceed these levels.  [c.46]

T T,-STEL is a I5-min, time-weighted average concentration to which workers may be exposed up to four times per day with at least 60 min between successive exposures with no ill effect if the TLV-TWA is not exceeded (developed by the ACGIH).  [c.2306]

Recommended exposure limit (8 hr time-weighted average concentration) Headache after about 7 hr if resting or after 2 hr exertion  [c.123]

Time-weighted average concentration, TWA, based on a 40-hour work week.  [c.605]

Care should be taken in handling and using iodine, as contact with the skin can cause lesions iodine vapor is intensely irritating to the eyes and mucus membranes. The maximum allowable concentration of iodine in air should not exceed 1 mg/nu (8-hour time-weighted average -40-hour).  [c.123]

Concentrations in air as low as IO7 g/ms can cause lung congestion, skin damage, or eye damage. Exposure to osmium tetroxide should not exceed 0.0016 mg/ms (8-hour time weighted average - 40-hour work week).  [c.141]

Exposure limits (threshold limit value or TLV) are those set by the Occupational Safety and Health Administration and represent conditions to which most workers can be exposed without adverse effects. The TLV value is expressed as a time weighted average airborne concentration over a normal 8-hour workday and 40-hour workweek.  [c.1198]

The time-weighted average (TWA) concentrations for 8-h exposure to bromine ttifluoride, bromine pentafluoride, chlorine ttifluoride, chlorine pentafluoride, and iodine pentafluoride have been estabHshed by ACGIH on a fluoride basis to be 2.5 mg/m. NIOSH reports (121) the foUowing inhalation toxicity levels for chlorine ttifluoride LC q monkey, 230 ppm/h LC q mouse, 178 ppm/h for chlorine pentafluoride LC q monkey, 173 ppm /h mouse, 57 ppm/h.  [c.187]

How Long to Sample. The period of the sample should be matched to the period of the exposure criteria. Most standards are referred to as eight hour time weighted averages (TWAs). These standards are for the average exposure over eight hours. Various combiaations of iadividual samples can be used to obtain the equivalent of what would have been measured by one sample of eight hours duration, as shown ia Figure 1. When the standard apphes to a shorter period, as for example a short-term exposure limit (STEL) which is a 15-min average, samples should be taken to measure over this shorter averaging time. Some limits are supposed to apply to instantaneous concentrations but because there are no truly instantaneous measurement methods (all have some response time) and because peak concentration is known to be a function of averaging time, these limits are somewhat undefined. The best solution when these limits are to be appHed is to make a very short (>1 min) period measurement.  [c.107]

The odor threshold for phosgene is ca 0.5—1 ppm, but it varies with individuals and is higher after prolonged exposure (53). Phosgene may irritate eyes, nose, and throat. The permissible exposure TLV by volume in air is 0.1 ppm (54). The TLV refers to the average airborne concentration at which it is beheved nearly aU workers may be repeatedly exposed on a daily basis without adverse effect. It is a time-weighted average for an 8-h day or a 40-h week and should be used as a guide for control only. The guideline for excursion limits above the TLV is 0.2 ppm (55). Long-term exposure to phosgene has been reviewed, and potential hazards may exist at concentrations slightly higher than the TLV (56). Medical problems and adverse health effects associated with phosgene exposure have been reviewed (57—59), and therapy for phosgene poisoning has also been reviewed (60).  [c.314]

Ceiling value concentration which should not be exceeded not appropriate to use a time-weighted average.  [c.95]

Threshold Limit Va.lue. The American National Standards Institute (ANSI) has pubHshed standards regarding the maximum acceptable concentration for certain gases and vapors in the air at work locations. A Hst of threshold limit values (TLVs), pubHshed annually by the American Conference of Governmental Industrial Hygienists (ACGIH), provides the concentrations of dust, mist, or vapor beHeved to be harmless to most workers when exposed for 5 8-h days per week (13). The 1970 TLVs were adopted by OSHA as a consensus standard for time-weighted averages (TWAs) or ceiling limits. The National Institute for Occupational Safety and Health (NIOSH) has documented concurrence with some of these values or has recommended different and usually lower values in a few cases (57). The American Industrial Hygiene Association (AIHA) has carefully evaluated the effect of several toxic vapors (47 as of 1995 (58)) and has developed Emergency response planning guides (ERPGs).  [c.96]

Physiological Effects. Propylene oxide has been studied extensively for its effects on humans and animals. Accordingly, it is regulated under several U.S. Federal statutes and agencies. OSHA has estabUshed a time-weighted average 8-h permissable exposure limit of 20 ppm (50 mg/m ). Because the odor threshold is about 200 ppm, the sweet penetrating odor of propylene oxide is not an adequate warning to prevent overexposure. Exposure to vapors above the permissible exposure limit can be irritating to the eyes and respiratory tract. Low concentrations can cause nausea high concentrations can cause pulmonary edema (2,3). Although there are no epidemiologic data for long-term exposure to humans, studies on animals suggest that propylene oxide is a possible human carcinogen and it is classified as such by NIOSH, lARC, and NTP (3). References 245 and 249—251 provide a summary of the pubhshed findings on propylene oxide carcinogenicity, mutagenicity, and teratogenicity in animals. Propylene oxide has been shown to cause central nervous system effects such as ataxia, incoordination, and depression in rats (252—254).  [c.143]

Health, Safety, and Environmental Factors. Sulfur dioxide has only a moderate acute toxicity (183). The lowest pubHshed human lethal concentration is 1000 ppm for 10 months. The lowest pubHshed human toxic concentration by inhalation is 3 ppm for 5 days or 12 ppm for 1 hour. The lowest pubHshed human lethal concentration is 3000 ppm for 5 months. In solution (as sulfurous acid), the lowest pubHshed toxic dose is 500 flg/kg causing gastrointestinal disturbances. Considerable data is available by other modes of exposure and to other species NIOSH standards are a time-weighted average of 2 ppm and a short-term exposure limit of 5 ppm (183).  [c.147]

Exposure to tantalum metal dust may cause eye injury and mucous-membrane irritation. The threshold limit value (TLV) in air is 5 mg/m, LD q is <400 mg/kg and the Occupational Safety and Health Administration (OSHA) time weighted average (TWA) exposure limit is 5 mg/m (47). The immediate dangerous to life or health (IDLH) concentration is 2500 mg/m (48). Whereas some skin injuries from tantalum have been reported, systemic industrial poisoning is apparently unknown (47).  [c.331]

THMs are formed by reaction of bromine and chlorine sanitizers not only with bather introduced contaminants, but also with ancillary chemicals. The average concentration of total trihalomethanes TTHMs (- 0.1 mg/m, 20 ppb) in air close to the surface of pool water is two orders of magnitude below the OSHA permissible exposure limit (8-h time weighted average) for the main THM chloroform in air (10 mg/m, 2 ppm) (75). The average concentration of TTHMs in the bulk air is signiftcantiy lower. Spas, with their higher bather load, will have a higher concentration than indoor pools which will be higher than outdoor pools. The average concentration of TTHMs in pool water tend to be at or above the drinking water standard (100 ppb) (72). However, this should be tempered by the fact that swimmers or bathers do not drink pool or spa water. Saline pools have shown higher concentrations of TTHMs due to higher levels of bromoform (72).  [c.304]

Various types of detector tubes have been devised. The NIOSH standard number S-311 employs a tube filled with 420—840 p.m (20/40 mesh) activated charcoal. A known volume of air is passed through the tube by either a handheld or vacuum pump. Carbon disulfide is used as the desorbing solvent and the solution is then analyzed by gc using a flame-ionization detector (88). Other adsorbents such as siUca gel and desorbents such as acetone have been employed. Passive (diffuse samplers) have also been developed. Passive samplers are useful for determining the time-weighted average (TWA) concentration of benzene vapor (89). Passive dosimeters allow permeation or diffusion-controlled mass transport across a membrane or adsorbent bed, ie, activated charcoal. The activated charcoal is removed, extracted with solvent, and analyzed by gc. Passive dosimeters with instant readout capabiUty have also been devised (85).  [c.46]

Safe Exposure Levels. The U.S. Occupational Safety and Health Administration (OSHA) has adopted workplace exposure limits designed to keep airborne concentrations weU below the levels known to cause health problems (35) including ( ) daUy time-weighted average (TWA) exposure over an eight-hour day is not to exceed beryUium concentrations of 2 lg/m of air and (2) short-term exposure should not exceed beryUium concentrations of 25  [c.69]

Because pulp bleaching agents are, for the most part, reactive oxidising agents, appropriate precautions must be taken in their handling and use. For example, it is important to ensure that the threshold limit values (TLV) (20) in Table 2 are not exceeded in the workplace air. These are airborne concentrations in either parts per million by volume under standard ambient conditions or mg per cubic meter of air. They "represent conditions under which it is beUeved that nearly all workers may be repeatedly exposed, day after day, without adverse effect" (20). TWA refers to a time-weighted average for an 8-h workday STEL is a short-term exposure limit or maximum allowable concentration to which workers can be continuously exposed for 15 minutes.  [c.158]

Consequences of Exposure. Bromine has a sharp, penetrating odor. The OSHA/ACGIH threshold limit value—time-weighted average for an 8-h workday and 40-h workweek is 0.1 ppm in air (61). Monitors are available for determining bromine concentrations in air. Concentrations of about 1 ppm are unpleasant and cause eyes to water 10 ppm are intolerable. Inhalation of 10 ppm and higher concentrations of bromine causes severe bums to the respiratory tract and is highly toxic. Symptoms of overexposure include coughing, nose bleed, feeling of oppression, dizziness, headache, and possibly delayed abdominal pain and diarrhea. Pneumonia may be a late complication of severe exposure.  [c.288]

The hquid and vapors of hydrobromic acid are highly corrosive to tissue. The threshold limit value for HBr gas in an 8-h day is 3 ppm time-weighted average. Inhalation of vapor is so irritating to the nose and throat that a person does not voluntarily remain in an area when vapors are present in hazardous concentrations. Symptoms of overexposure to HBr include coughing, choking, burning in the throat, wheezing, or asphyxia.  [c.291]

The time-weighted average limit for daily 8-h exposure to the vapor in air is 5 ppm by volume, or 19 mg/m (67). A full facepiece gas mask with an appropriate canister may be used in areas where the concentration of methyl bromide is known and is no more than 2000 ppm. For unknown or higher concentrations a positive pressure, self-contained breathing apparatus is required. A full facepiece respirator should be worn whenever there is a likelihood of getting methyl bromide in the eyes. No gloves, finger rings, or adhesive bandages should be worn on the hands and no ordinary mbber protective clothing or boots should be worn when handling methyl bromide. If contaminated, clothing should be removed promptly and shoes should be discarded. Wash faciHties for eyes and skin should be provided near work areas (82).  [c.294]

The 1991 Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL), 8-h time-weighted average standard (TWA) is 100 P-g/m of air for cadmium fume, having a ceiling concentration of 300 pg/m, and 200 pg/m of air for cadmium dust, 600 pg/m ceiling concentration. In 1990, the American Conference of Governmental Industrial Hygienists (ACGIH) specified a threshold limit value (TLV) and ceiling concentration of 50 pg/m for both cadmium fume and dust. However, in 1991 the ACGIH proposed a TLV of 10 pg/m total cadmium and 2 pg/m respirable fraction, along with an A2 suspected human carcinogen designation. Meanwhile, the National Institute of Occupational Safety and Health (NIOSH) recommended a PEL of 40 pg/m for both cadmium fume and dust at a 200 pg/m ceiling concentration for both. EinaHy, in 1991 OSHA proposed to lower the PEL to a level of 1 pg/m or 5 pg/m for cadmium and all cadmium compounds.  [c.388]

The recommended NIOSH limit of 35 ppm is the time-weighted average exposure to carbon monoxide based on a carboxyhemoglobin level of 5% this amount of COHb is what an employee engaged in sedentary activity would be expected to approach in eight hours of continuous exposure. The standard does not take into account the smoking habits of a worker the level of COHb in chronic cigarette smokers has generally been found to be in the 4—5% range prior to carbon monoxide exposure (105). A concentration of 100 ppm is allowable for an exposure of several hours and 400—500 ppm can be inhaled for one hour without an appreciable effect, whereas 1500—2000 ppm are dangerous and 4000 ppm or more is fatal (106). First aid treatment for carbon monoxide poisoning emphasizes elimination of the gas from the body. Elimination of carbon monoxide occurs solely through the lungs, and though rapid at first, the last traces are difficult to remove. The poisoned patients must be removed to fresh air, kept warm, and adininistered pure oxygen by the best method available. Artificial respiration is necessary whenever breathing is inadequate. Exercise and stimulants, including carbon dioxide, must not be given because they can lead to coUapse. A physician must be summoned in all cases of suspected carbon monoxide poisoning (107).  [c.59]

Methylene chloride is one of the least toxic chlorinated methanes. The LD q in rats is in the range of 1.6—3.0 g/kg body weight. The fatal dose for a 68-kg person ranges from 80 mL (1.5—2.5 02) to 470 mL (1 pint). Methylene chloride is painful and irritating if splashed directly into the eye. The ACGIH threshold limit value (TLV) for methylene chloride is 50 ppm by volume for an eight-hour exposure. The OSHA permissible exposure level is 500 ppm time-weighted average, 1000 ppm ceiling with 2000 ppm peak concentration. This is currently under revision.  [c.521]

Toxicity. 1,1-Dichloroethane, like all volatile chlorinated solvents, has an anesthetic effect and depresses the central nervous system at high vapor concentrations. The 1991 American Conference of Governmental Industrial Hygienists (ACGIH) recommends a time-weighted average (TWA) solvent vapor concentration of 200 ppm and a permissible short term exposure level (STEL) of 250 ppm for worker exposure. The oral LD q of  [c.7]

For worker exposure to trichloroethylene vapor, OSHA set a maximum eight-hour time-weighted average (TWA) concentration of 100 ppm. This severely restricted certain appHcations, and many organizations converted to other chlorinated solvents. As a result, U.S. production of trichloroethylene declined about 70% from a peak in 1970 (Table 2). In 1989, OSHA lowered the permissible exposure limit (PEL) from 100 ppm eight-hour TWA to 50 ppm eight-hour TWA (33). This added further pressure for some users to consider changing to alternative solvents.  [c.24]

Respiratory effects are the primary toxicological manifestations of repeated overexposure to diisocyanates (54). Once a person is sensiti2ed to isocyanates, lower concentrations can trigger a response (55). Most of the industrial diisocyanates are also eye and skin irritants. Controlling dermal exposure is good industrial hygiene practice. The 1997 American Conference of Governmental Industrial Hygienists (ACGIH) exposure guideline for TDl is 0.005 ppm as a TWA-TLV (an eight-hour time-weighted average concentration) the 1997 TLV for TDl in Japan is 20 ppb.  [c.353]

TLV-TWA is the time-weighted average concentration hmit for a normal 8-h day and 40-h worlweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect (developed by the ACGIH).  [c.2306]

The problem of determining the exposure of a worker to air contaminants is further complicated by the mobility of most workers who move about, in and out of, many areas of a workroom. This mobility is characteristic of many assigned jobs. Therefore, the concentration of contaminants in each work area, and the time spent in each must be considered in determining the full shift time-weighted average concentration to which each worker is exposed. Exposure is concentration averaged over a time period, which in the general case is a full 8-hour shift. However, threshold limit values in the list published in the OSHA safety and health standards are peak concentrations or "ceiling values." Such standards indicate the maximum concentration which is allowed for any time period. Although a single specific sampling strategy cannot be applicable for all air monitoring, general principles or considerations, which should be incorporated in such a strategy, can be developed.  [c.262]

LJsually, OELs are stated as the eight-hour time-weighted average concentration of exposure to a substance in gaseous, vaporous, or suspended form in the air at the workplace. Later on we will give a more precise formula.  [c.363]

TLV-TWA is defined as the time-weighted average concentration for a normal 8-hour workday and a 40-hour workweek, to wliich nemly all workers may be repeatedly c.xposcd, dtiy after day, witliout any long-tenii adverse effect.  [c.233]

Hydrogen selenide in a concentration of 1.5 ppm is intolerable to man. Selenium occurs in some solid in amounts sufficient to produce serious effects on animals feeding on plants, such as locoweed, grown in such soils. Exposure to selenium compounds (as Se) in air should not exceed 0.2 mg/m3 (8-hour time-weighted average - 40-hour week).  [c.97]

Remote sensing is the measurement of changes in the open air at a distance. Infrared transmission spectrometry with an open beam path is a common remote-sensing method, and infrared emission can be used if the monitoring target, such as a stack-gas plume is hot. For open-path transmission spectrometry, the elements of a conventional spectrophotometer are rearranged. The infrared source is separated from the rest of the instmment and fitted with a telescope to produce a wide, collimated beam along the monitoring path, which acts as the sample ceU. The spectrometer is also fitted with a telescope to coUect the beam, which can then be detected and analy2ed in the normal manner. Often source-beam modulation and phase-sensitive detection are used to differentiate between the source beam and background infrared sources and improve the signal-to-noise ratio. The simplest arrangement is the bistatic configuration, in which the infrared source and the spectrometer are on opposite ends of the monitoring path, but this requites a power source and very stable mounting at both ends of the path. The monostatic configuration has both the source and the spectrometer at one end of the path and a set of retroreflectors at the other, so the beam traverses the path twice. The monostatic configuration is less vibration sensitive and it simplifies synchronization when phase-sensitive detection is used. Open-path transmission measures the total absorbance along the beam path, so the measurement determines the length-weighted average concentration along the path. Open-path measurements are therefore usually given in units of concentration times length. Typical limits of detection are 1 to 100 ppmv m. A special form of open-path spectrometry is a variant of light detection and ranging (Udar) called differential absorption Hdar (dial). In Hdar a beam is aimed at the plume and the backscatter resulting from absorption is measured. In dial, the infrared source is normally a laser capable of emission at two nearby wavelengths. One of the wavelengths is within the absorption band of the species to be monitored and the other is outside the band. The difference in absorption between the two wavelengths is largely independent of any broad-band interferences, eg, scattering by dust and background sources. The CO2 laser is the most common source for infrared dial because it functions in the fingerprint region (48,49).  [c.200]

Human Exposure to Ozone. The toxicity of ozone is largely related to its powerful oxidizing properties. The odor threshold of ozone varies among individuals but most people can detect 0.01 ppm in air, which is well below the limit for general comfort. OSHA has estabhshed a time-weighted average permissible exposure level for workers for an eight-hour day of 0.10 ppm v/v (0.2 mg/m ) and a short-term exposure limit of 0.30 ppm v/v (0.6 mg/m ) for an exposure less than 15 minutes (160). The latter is based on observations showing that significant declines in pulmonary function can result from repeated intermittent exposures or from a single short-term exposure to ozone. The toxicity of gaseous ozone varies with concentration and exposure time (161). The symptoms experienced on exposure to 0.1—1 ppm ozone ate headache, throat dryness, irritation of the respiratory passages, and burning of the eyes caused by the formation of aldehydes and petoxyacyl nitrates. Exposure to 1—100 ppm ozone can cause asthma-like symptoms such as tiredness and lack of appetite. Short-term exposure to higher concentrations can cause throat irritations, hemorrhaging, and pulmonary edema. Additional toxicity data is given in Reference 162.  [c.504]

Occupational Safety and Health Act. OSHA has broad responsibihties for protecting the workplace. The Occupational Safety and Health Act is administered by the Occupational Safety and Health Administration under the U.S. Department of Labor (12). The act covers all health and safety aspects of a worker s environment. Subpart Z of the Act, Toxic and Ha2ardous Substances, Hsts allowable employee exposure to many different chemical substances (13). These are given as ambient air concentrations over a certain time period, which usually is an 8-h time-weighted average. Sometimes a ceiling concentration is given as well. Certain substances, eg, vinyl chloride, ben2ene, and formaldehyde, are discussed in terms of necessary controls and limits. The monitoring of employee exposure is called industrial hygiene (qv).  [c.79]

Vinyl chloride is an OSHA-regulated substance (146). Current OSHA regulations impose a permissible exposure limit (PEL) to vinyl chloride vapors of no more than 1.0 ppm averaged over any 8-h period. Short-term exposure is limited to 5.0 ppm averaged over any 15-min period. Contact withHquid vinyl chloride is prohibited. Monitoring is required at all faciUties where vinyl chloride is produced or PVC is processed. OSHA regulations also define an action level of 0.5 ppm, 8-h time-weighted average. Employers must demonstrate that monitoring results show exposure below the action level of 0.5 ppm on subsequent readings taken not less than five working days apart in order to discontinue monitoring. Where concentrations cannot be lowered below the 1.0-ppm PEL, the employer must estabUsh a regulated area with controlled access, a respirator program conforming to paragraph g of the OSHA standard (146), and a written plan to reduce vinyl chloride levels. OSHA regulations require faciUties that handle vinyl chloride to develop a medical surveillance program with annual physical examinations and blood semm analyses for all employees exposed at levels above the action level. Surveillance frequency increases to semiannually for these employees when they attain 10 or more years of service in the manufacture of vinyl chloride.  [c.423]

Chemical pneumonitis or pulmonary edema may result from acute exposure to cadmium fumes, as oxide or chloride aerosols, at a dose of 5 mg/m over an 8-h period. One mg/m inhaled over the same time period gives rise to clinically evident symptoms in sensitive individuals. Deaths from acute cadmium poisoning have resulted from inhalation of cadmium oxide smokes and fumes, usually from welding operations on cadmium plated steels in poorly ventilated areas. Acute ingestion of cadmium concentrations above 15 ppm (0.1 1.0 mg/(kg-d)) produce symptoms of nausea, vomiting, abdominal cramps, and headache (25). Possible sources of such poisoning have been traced to cadmium-plated cooking utensils, cadmium solders in water coolers, or from acid juices stored in ceramic pots gla2ed using cadmium-containing compounds. Current atmospheric time-weighted average (TWA) permissible exposure limits (PEL) are 200 p.g/m (dust) or 100 p.g/m (oxide fumes) in an 8-h workday (25). OSHA, in Eebmary 1990, proposed (14) a new PEL level of either 5 or 1 p.g/m for all forms of airborne cadmium and as of this writing this standard is under review. Acceptable OSHA 15-min ceiling concentrations are 600 p.g/m for dusts and 300 p.g/m for oxide fumes (25). The maximum for dissolved Cd in drinking water recommended by WHO is 5 [ig/L (15,25).  [c.393]


See pages that mention the term Time Weighted Average Concentration : [c.397]    [c.321]    [c.114]    [c.239]    [c.33]   
Health, safety and accident management in the chemical process industries (2002) -- [ c.321 ]