Time-weighted average exposure


The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that time weighted-average exposures for DMF not exceed 10 ppm or 30 mg/m (skin designation, 1989 standard) for an eight-hour work day. In the United States, OSHA has accepted the ACGIH limits ia setting regulations for worker exposures. As with other iadustrial chemicals, regulations and expert opinion evolve over time, and DMF exposure limits may be tightened ia the future. A Biological Exposure Index (BEI) of 40 mg DME metaboUtes /g of creatinine ia urine has also been adopted by ACGIH and apphes ia cases where there is significant potential for absorption of DME is Hquid or vapor through the skin.  [c.515]

The toxicity of sodium peroxoborate is similar to that of the hexahydrate. The LD q (cat, intravenous) is 600 mg/kg the LD q (rabbit, intravenous) is 78 mg/kg (28). Sodium peroxoborate is a severe eye irritant, but not a skin irritant. Absorption through large areas of abraded or damaged skin can give systemic boron poisoning (2). The maximum eight-hour time-weighted average exposure is 5 mg/m (2).  [c.93]

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]

Carboxyhc acid dust and vapors are generally described as being destmctive to tissues of the mucous membrane, eyes, and skin. The small molecules such as formic, acetic, propionic, butyric, and acryUc acids tend to be the most aggressive (Table 11) (83). Formic, acetic, propionic, acryUc, and methacrylic acids have time weighted-average exposure limits of 20 ppm or lower. AcryUc acid showed an LD q of 33.5 mg/kg from oral adrninistration to rats.  [c.86]

Basically a TLV refers to a time-weighted averaged exposure for a 7 or 8-hour work day and a 40-hour work week. In other words, it is a level directed toward chronic (long-term) exposure and not toward acute (short-term) exposure. Generally, toxicity data for acute exposures is obtainable largely from animal experimentation, early medical data, and limited information from accidental exposures. In the use of TLVs, it is important to recognize that the levels are generally developed for normal individuals doing normal work. Under conditions of high heat, unusual humidity, heavy exertion, abnormal pressure, or other work factors which may place added stress on the body, the effects from exposure to an air contaminant at its TLV may be altered. Generally, most of these stresses act adversely to increase the toxic response to a substance, and proper downward adjustment of the level should be made.  [c.257]

Excursion Factors. Most TLVs refer to time-weighted average exposures for an 8-hour work day and a 40-hour work week. However, in calculating time-weighted average exposure, excursions above the limit are permitted provided they are compensated for by equivalent excursions below the limit during the same work day. The question here is "How much of a fluctuation above the limit is permissible in developing the average " These fluctuations above the limits are related to the magnitude of the TLV for the particular substance (refer to Table 1).  [c.257]

Ceiling "C" Values-. "C" designations following the names of some substances refer to a ceiling value which should not be exceeded for that substance for any period of time. In other words, the time-weighted average exposure should fluctuate below the C value. Generally, C values are assigned to substances whose action is chiefly irritation, narcosis, or productive of serious long-term effects from a single or a few peak exposures. These are usually fast-acting substances whose TLV is more appropriately based on a ceiling value than on a time-weighted average which allows excursions above listed values.  [c.258]

As an example, several air samples collected during an 8-hour work shift for benzene (8-hour time-weighted average = 10 ppm) were 3 hours at 4 ppm, 1 hour at 15 ppm, 2 hours at 6 ppm and 2 hours at 9 ppm. The employee s time-weighted average exposure would be  [c.260]

Another type of time-weighted average exposure limit is the decision level (DL), which is expressed as a fraction of the OEL. In general, it is based on judgment, and it is greater than a dose of 50% and usually corresponds to one-fourth of the dose. For special substances, such as carcinogens, it should  [c.366]

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

Ozone s presence in the atmosphere (amounting to the equivalent of a layer 3 mm thick under ordinary pressures and temperatures) helps prevent harmful ultraviolet rays of the sun from reaching the earth s surface. Pollutants in the atmosphere may have a detrimental effect on this ozone layer. Ozone is toxic and exposure should not exceed 0.2 mg/m (8-hour time-weighted average - 40-hour work week). Undiluted ozone has a bluish color. Liquid ozone is bluish black and solid ozone is violet-black.  [c.21]

It is very poisonous, 50 mg constituting an approximate fatal dose. Exposure to white phosphorus should not exceed 0.1 mg/ms (8-hour time-weighted average - 40-hour work week). White phosphorus should be kept under water, as it is dangerously reactive in air, and it should be handled with forceps, as contact with the skin may cause severe burns.  [c.36]

Exposure to chlorine should not exceed 0.5 ppm (8-hour time-weighted average - 40 hour week.)  [c.42]

While silver itself is not considered to be toxic, most of its salts are poisonous. Exposure to silver (metal and soluble compounds, as Ag) in air should not exceed 0.01 mg/nu, (8-hour time-weighted average - 40 hour week). Silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body. A condition, known as argyria, results with a grayish pigmentation of the skin and mucous membranes. Silver has germicidal effects and kills many lower organisms effectively without harm to higher animals.  [c.65]

Exposure to nickel metal and soluble compounds (as Ni) should not exceed 0.05 mg/cms (8-hour time-weighted average - 40-hour work week). Nickel sulfide fume and dust is recognized as being potentially carcinogenic.  [c.68]

Exposure to cobalt (metal fumes and dust) should be limited to 0.05 mg/ms (8-hour time-weighted average 40-hour week).  [c.84]

Exposure to rhodium (metal fume and dust, as Rh) should not exceed 1 mg/m 3 (8-hour time-weighted average, 40-hour week).  [c.111]

Exposure to hafnium should not exceed 0.5 mg/hr. (8 hour time-weighted average - 40-hour week).  [c.131]

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]

The element and its compounds are toxic and should be handled carefully. Contact of the metal with skin is dangerous, and when melting the metal adequate ventilation should be provided. Exposure to thallium (soluble compounds) - skin, as Tl, should not exceed 0.1 mg/ms (8-hour time-weighted average - 40-hour work week). Thallium is suspected of carcinogenic potential for  [c.145]

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]

Although acetonitrile has a low order of acute toxicity by ingestion, inhalation, and skin absorption, it can cause severe eye bums. In case of eye contact, eyes should be immediately flushed with water for at least 15 min and a physician should be consulted. In the event of a spiH or leak, the spiH should be contained, flooded with water, and disposed of according to local regulations. Acetonitrile is flammable (see Table 2) and must be kept away from excessive heat, sparks, and open flame. Associated fires can be extinguished using water spray, alcohol foam, CO2, or dry chemical extinguishers. OSHA requites that an employee s exposure to acetonitrile in any 8-h shift does not exceed a time-weighted average of 40 ppm (70 mg/m ) in air (30).  [c.219]

The U.S. Department of Labor (OSHA) has ruled that an employee s exposure to dimethyl acetamide in any 8-h work shift of a 40-h work week shall not exceed a time-weighted average of 10 ppm DMAC vapor in air by volume or 35 mg/m in air by weight (7). If there is significant potential for skin contact with DMAC, biological monitoring should be carried out to measure the level of DMAC metaboHtes in urine specimens collected at the end of the shift. One industrial limit is 40 ppm DMAC metaboHtes, expressed as AJ-methylacetamide [79-16-3] for individuals, and 20 ppm metaboHte average for workers on the job (8).  [c.85]

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]

Styrene toxicity is regarded to be relatively low. It is an irritant to the eyes and respiratory tract, and while prolonged exposure to the skin may cause irritation, styrene is unlikely to be absorbed through the skin in harm fill amounts. The American Conference of Government Industrial Hygienists (ACGIH) threshold limit value (TLV) for styrene is 50 ppm time-weighted average (TWA) (155). More information on human exposure to styrene in the workplace is available (156,157) (see Styrene).  [c.197]

The American Conference of Governmental Industrial Hygienists (ACGIH) has estabUshed the 8-hour time-weighted average TLV as 1 ppm or 1.6 mg/m, and the short-term exposure limit TLV as 2 ppm or 3.1 mg/m. Fluorine has a sharp, penetrating odor detectable at levels well below the TLV. Manifestations of overexposure to fluorine include irritation or bums of the eyes, skin, and respiratory tract. The following emergency exposure limits (EEL) for humans have been suggested (107) 15.0 ppm for 10 min 10 ppm for 30 min and 7.5 ppm for 60 min.  [c.131]

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]

Handling and Toxicity. Tungsten hexafluoride is irritating and corrosive to the upper and lower airways, eyes, and skin. It is extremely corrosive to the skin, producing bums typical of hydrofluoric acid. The OSHA permissible exposure limits is set as a time-weighted average of 2.5 mg/kg or 0.2 ppm (22).  [c.258]

OSHA has a standard time-weighted average (TWA) of 2.5 mg/m based on fluoride. NIOSH has issued a criteria document (24) on occupational exposure to inorganic fluorides.  [c.260]

The threshold limit value for the time-weighted average (8-h) exposure to pentanes is 600 ppm or 1800 mg/m (51 mg/SCF) the short-term exposure limit (15 min) is 750 ppm or 2250 mg/m (64 mg/SCF) (39). Pentanes are classified as simple asphyxiants and anesthetics (qv).  [c.404]

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]

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]

Formaldehyde. The toxicology and possible carcinogenicity of formaldehyde have been a matter of intense research. Formaldehyde is classified as a probable human carcinogen by the International Agency for Research on Cancer (lARC) and as a suspected human carcinogen by the American Conference of Governmental and Industrial Hygienists (ACGIH) the latter has lowered its TLV to 0.3 ppm. The Occupational Safety and Health Administration (OSHA) has set its time-weighted average for eight hours at 1.0 ppm and its short-term exposure level at 2.0 ppm (67).  [c.302]

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]

Phosphine has an 8-h time-weighted average exposure limit of 0.3 ppm (13). Under alkaline conditions the rate of PH formation is high. At neutral or acidic pH, the PH generation is slow but stiU very ha2ardous if the PH is allowed to accumulate in a confined vapor space. The safest commercial handling conditions for molten phosphoms are generally considered to be from pH 6 to 8 at 45—65°C.  [c.352]

Health and Safety Factors. Trichloromethanesulfenyl chloride is extremely toxic and mutagenic (64). It has an LD q in rabbits (percutaneous) of 1410 mg/kg (65,66) and an LC q in tats (male) of 11 ppm/h (66). The LD q oral in tats is 83 mg/kg (64). There ate ha2atds involved from inhalation and possible skin contact. Severe local irritation can result from contact of the Hquid or vapor with the skin, eyes, mucous membranes, and upper respiratory tract. The irritating nature of the vapor may also serve as a warning of its presence. The MSDS should be consulted and all work carried out with good ventilation in a laboratory fume hood with the operator wearing proper gloves, suitable protective clothing, and respiratory equipment. The TLV of trichloromethanesulfenyl chloride is an 8-h time-weighted average exposure of 0.1 ppm (0.8 mg /m ).  [c.132]

Toxicity data are presented in the literature by such terms as "LDjo" and "LC50, that lethal dose per kilogram of body weight or lethal concentration that can kill 50 percent of an animal population. Such data are found, for example, in the Registry of Toxic Effects of Chemical Substances (RTECS). With data such as these obtained from animals closely resembling the human in biochemistry, relative toxicities can be established to characterize chemicals. These data in conjunction with air contaminant threshold limit values (TLV) or permissible exposure limits (PEL), set by law for short periods of exposure or eight-hour, time-weighted average exposure, have produced safe working exposure limits for the worker. Many of these values are contained in the OSH A Standards and the American Conference of Governmental Industrial Hygienist s (ACGIH) in their publications on Threshold Limit Values and Biological Exposure Indices.  [c.181]

Inert" or Nuisance Particulates Some materials may be classified as "inert" or nuisance particulates. Table 2 gives some examples. Generally, these materials have a long history of little adverse effect on the lungs and do not produce significant organic disease or toxic effect when exposures are kept under reasonable control. However, excessive concentrations of "inert" or nuisance particulates in the work air may seriously reduce visibility (iron oxide), may cause unpleasant deposits in the eyes, ears and upper respiratory passages (e.g., Portland cement and limestone dust), or may cause injury to the skin or mucous membranes during rigorous cleaning or mechanical action. To control these effects, a TLV for particulates with less than 1 % free silica has been set at 10 mg/m or 30 ppm cf (whichever is less) of total dust. The mg/m refers to a gravimetric standard and the mppcf to a particle count standard. The limits do not apply to brief exposures to higher concentrations during a normal work day, nor do they apply to substances which may cause physiologic impairment at lower concentrations, for which no TLV has been indicated. Time-weighted average exposures for an 8-hour work shift are calculated by the following formula (where E = time-weighted average exposure, C = concentration during any period of time where the concentration remains constant, and T = duration, hrs.)  [c.259]

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]

Germanium compounds generally have a low order of toxicity (24). Only germane [7782-65-2] GeH, is considered toxic, having a maximum time-weighted average 8-h safe exposure limit of only 0.2 ppm (48). The lethal dose median for Ge02 is 750 mg/kg, and that of germanium is 586 mg/kg (49). The toxicity of specific germanium compounds usually must be considered more from the standpoint of the other part of the compound than from the Ge content. The biological activity of germanium has been reviewed (24).  [c.281]

Nitric acid and the oxides of nitrogen found in its fumes are highly toxic and capable of causing severe injury and death. It is corrosive and can destroy human tissue. Nitric acid is regulated by OSHA, which Hsts it as a Process Safety Hazardous Chemical and Air Contaminant. Under SARAH, the EPA Hsts it as an Extremely Hazardous Substance and Toxic Chemical. Per OSHA, the 1991 permissible exposure limits for nitric acid are 2 ppm (5 mg/m ) for an 8-h time-weighted average and 4 ppm (10 mg/m ) for a 15-min short-term exposure. Exposure limits may vary according to local and national regulations. Inhalation symptoms may take several hours to appear. They include irritation of the throat and nose, coughing, chest pain, difficulty in breathing, giddiness, nausea, ulceration of the nasal mucous membranes, pulmonary edema, and chemical pneumonia. The symptoms resulting from skin contact vary from moderate irritation to severe bum, depending on contact time and strength of the nitric acid. Signs of contact may include a yellow discoloration of the skin severe bums may penetrate deeply causing ulceration and the scarring of tissue.  [c.47]

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]

Health and Safety Factors. Trimellitic anhydride may cause respiratory irritation and, in some cases, individuals exposed over long periods may become sensitized and experience mild to severe reactions upon subsequent exposure. It should be handled with caution and treated as a toxic agent in the workplace because exposure may result in irritation of the pulmonary tract, eyes, nose, and skin (117), immunological sensitization and, in rare cases, hemolytic anemia and noncardiac pulmonary edema. Allowable and recommended exposure limits have been estabUshed by the Occupational Safety and Health Administration for a permissible exposure limit (PEL), the American Conference of Governmental Industrial Hygienists for a threshold limit value (TLV), and Amoco for a ceiling limit are aU 0.4 mg/m. The PEL and TLV are an 8-h time-weighted average. The mean lethal acute oral dosage in rats is 5.6 g/kg. Handling precautions include effective ventilation and use of respirators, protective clothing, and goggles when exposure to dust is expected.  [c.497]

The U.S. Department of Labor (OSHA) has ruled that an employee s exposure to aniline in an 8-h work shift of a 40-h work week shaU not exceed an 8-h time-weighted average (TWA) of 5 ppm vapor in air. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends a  [c.232]

Diphenylamine ia the basic diet of rats at 0.5—1.5% inhibits growth and causes fiver and kidney disorders (36). Industrial poisoning by diphenylamine has been encountered and appears clinically as bladder symptoms, tachycardia, hypertension, and skin problems (37). There is no federal standard for permissible exposure limits ia air, but the American Conference of Government Industrial Hygienists (1983/84) has adopted a Time Weighted Average value of 10 mg/m and set a Short Term Exposure Limit of 20 mg/m. The alkylated diphenylamiaes, used as antioxidants, have much higher molecular weights and are relatively nonvolatile.  [c.244]


See pages that mention the term Time-weighted average exposure : [c.233]    [c.114]    [c.224]    [c.239]    [c.171]   
Industrial ventilation design guidebook (2001) -- [ c.323 , c.363 , c.366 , c.605 , c.1484 ]