Work place concentrations

In manufacturing and processing in GRP plant, styrene and solvents must be extracted to prevent excessive concentrations in the air. In 1987 the permitted work-place concentration for styrene was reduced from lOOppm to 20ppm. From 31-12-94 values above 20ppm are no longer permitted where UP resins are processed manually. Exact measurement of concentrations is essential and suitable extraction systems installed. 

The odor limit compared to other limits may indicate an early warning of a leak. The maximum allowed work place concentration (MAC), is the maximum allowed average concentration expressed in mgnT3 of a gas, vapor, or dust in air in a workplace, which has no adverse effects on health for an exposure of 8 hours per day or 42 hours per week for the majority of a population. Since it is an average, maintaining the concentration below this value does not guarantee no effects, since the sensitivity may differ within a population. On the other hand, a shortterm exposure to a concentration above MAC does not imply consequences on health. 

Acetic acid vapor in concentrations above 50 ppm causes irritations of mucous membranes. For this reason, the maximum admissible work place concentration is 10 ppm. The smell threshold lies between 1 and 5 ppm. 

Dihydropyran is harmful if absorbed by the skin, inhaled, or ingested. Its vapor or mist is irritating to the eyes, to mucous membranes, and to the upper respiratory tract, but a maximum admissible work place concentration has not been established as yet. 

Toxicology LD50 (rat p. 0.) 320 mg/kg. H. irritates the skin, eyes, and airways. Lethal dose 5 -12 g (humans) maximum working place concentration 2 mg/m, possibly cancerogenic. Its use in cosmetics is allowed with limitations. 

Activity R. attacks the respiratory chain, blocks the oxidation of NADH2 coupled with the reduction of cytochrome b, and interrupts mitochondrial electron transport. R. is not toxic to bees, the LDjg (rat p. 0.) is 133 mg/kg or (mouse i.p.) 2.8 mg/kg. The maximum allowed working place concentration is 5 mg/m. Use of R. is restricted by legislation, the estimated LDjo (human p.o.) is 0.3-0.5 g/kg (higher toxicity on inhalation). 

All indications are given in good faith and conscience. This also applies for the maximum working place concentrations (MWC), the acceptable daily intake (ADI) values and to the data with regard to ecotoxicity and biodegradability of microbicides which, as far as accessible, were also incorporated. 

OF2 is extremely toxic. The colorless gas irritates the lungs and has a characteristic foul odor detectable to about 0.1 ppm. Concentrations of about 0.5 ppm are easy to detect. Because of the high toxicity of the compound and the rapid desensitization to its odor, inhalation should be absolutely avoided [1 to 4]. The maximum working-place concentration should be <0.005 ppm. The ceiling value 0.05 ppm together with short-term inhalation values have been reported [5]. 

Rash point, explosion limits, toxicity, maximum working place concentration, lower and upper flammability limits... 

Concentrates are made in the same manner as dispersions but often with less work placed into the colorant—vehicle system, thus higher yields and rates are obtained and a lower cost product is made. Usually, the concentrate goes through an additional processing step with the resin in which additional energy is provided to the system, thus ensuring more dispersion. 

Lethal concentration 50 (LC50) is the vapour concentration of a substance in air, which kills 50% of the animals exposed. This estimate comes from a protocol that was statistically controlled. This value depends on the animal chosen for the experiments and exposure time. The three animals that are most commonly used are in descending order rat, mouse and rabbit. It is a parameter that estimates risk level by inhalation, which is the most important means of penetration involving toxic substances in the work place. 

Chronic-Duration Exposure and Cancer. Some reports of occupationally exposed workers indicated that low concentrations of hydrogen cyanide may have caused neurological, respiratory, and cardiovascular effects (Blanc et al. 1985 Chandra et al. 1980, 1988 El Ghawabi et al. 1975 Kumar et al. 1992). The route of exposure was predominantly inhalation, although dermal exposure can also occur in the work place. The studies, however, lacked either information about exposure levels or used small cohorts of workers. Studies in populations that used cassava roots as a main source of their diet described the neurological effects of cyanide consumption (Osuntokun 1972, 1980). However, these effects may be due to a recently identified substance, scopeletin, rather than due to cyanide (Obidoa and Obasi 1991). 

This review does not deal specifically with all the categories mentioned above, but takes into account compounds which are formed at the work place and result in direct exposure and preformed nitroso compounds. The latter are formed from amines or contain high concentrations of amino compounds. The contamination may arise as a result of contaminated starting material, in particular amines or from the formation of NOC during the manufacturing cycle. 

Assume a worker is exposed to the maximum allowable air concentration of a work place carcinogen, eight hours every day, five days... 

The quantitative determination of small concentrations of organic solvents in a working place atmosphere by IR spectroscopy has been reported by Schacke et al. (1972). The measurements were carried out using a multipass gas cell with a maximum pathlength of 10 m. Such cells allow the determination of compounds in the ppm or even ppb region. 

It is however a very difficult task that I am supposed to fulfill in half an hour. We enter indeed into a very wide and controversial subject the toxicity of small concentrations of chemical substances, commonly called the pollutants (in food, air, water, wastes, fertilizers, working places, etc—), a field where the amount of really relevant knowledge is not yet very extensive. 

No fundamental progress on methods of the manufacture of NG can be recorded. The main efforts have been concentrated on the problem of increasing the safety of the processes by using perfect automation with remote control devices, avoiding immediate contact between personnel and dangerous parts of the process and the reduction of the quantity of explosive in the working place. All these requirements can be achieved with continuous methods, allhougfi batch processes are still in use. 

Ethylene glycol dinitrate is more toxic than nitroglycerine because of its lugtier volatility, According to Meyer [72, 73) the maximum permitted concentration in a work place is 1.5-1.6 mg m. ... 

In contrast to the isolation of the peasantry, the physical proximity of the workers to each other in the factory enhances their solidarity and overcomes the mutual competition. They are disciplined, united, organized by the very mechanism of the process of capitalist production itself", Marx also states that "the dispersion of the rural labourers over large areas breaks down their power of resistance while concentration increases that of the town operatives", and more generally that "the power of resistance of the labourers decreases with their dissemination". He does not say explicitly that it is the concentration in the work-place, rather than in housing and residence, that is the decisive factor, but from what he says elsewhere about the importance of trade unions this can reasonably be inferred. ... 

In clinical analysis, flame AAS is very useful for serum analysis. Ca and Mg can be determined directly in serum samples after a 1 50 dilution, even with microaliquots of 20-50 pL [314]. In the case of Ca, La3+ or Sr2+ are added so as to avoid phosphate interferences. Na and K are usually determined in the flame emission mode, which can be realized with almost any flame AAS instrument. The burner head is often turned to shorten the optical path so as to avoid self-reversal. For the direct determination of Fe, Zn and Cu, flame AAS can also be used but with a lower sample dilution. Determination of trace elements such as Al, Cr, Co, Mo and V with flame AAS often requires a pre-concentration stage, but in serum and other body fluids as well as in various other biological matrices some of these elements can be determined directly with furnace AAS. This also applies to toxic elements such as Ni, Cd and Pb, which often must be determined when screening for work place exposure. When aiming towards the direct determination of the latter elements in blood, urine or serum, matrix modification has found wide acceptance in working practices that are now legally accepted for work place surveillance, etc. This applies e.g. for the determination of Pb in whole blood [315] as well as for the determination of Ni in urine (see e.g. Ref. [316]). 

There do not exist any special values for permissible concentrations of hardmetal dust on the work place. Therefore, the MAK values for insoluble W and Co are valid (5mgWC/m and 0.5mgCo/m ). The ITIA (see Section 13.6) is encouraging inducing enhanced activity in regard to acute toxicity tests to be conducted on tungsten compounds including hardmetals (ITIA Newsletter, Jime 1997). 

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