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Results for “Maximum Allowable Concentration”

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At least 199 records · Page 11Linked to original sources
PubMed1984

Short-term systems to assess thiophosphoryl chloride standards.

The rat acute oral LD50 value of PSCl3 is 750 mg per kg body weight. A rat 90-day oral feeding study at dose levels of 7.5 mg (P1) and 37.5 mg (P5) per kg resulted in increased body weight gain. Other responses inconsistently varied between dose levels. At 7.5 mg kg-1, a trend towards enhancement of relative weight of liver, spleen, kidney and adrenals was noted; at 37.5 mg kg-1, decreasing relative spleen and adrenal weights were observed. The most of the hematological and biochemical changes in blood serum cannot be believed to be transitory adaptive changes, but valid toxic effects. On the other hand, there are some indicators that suggest a possible trophic effect of this compound. However, the reversible dystrophic changes in liver, as well as the histochemical and histoenzymical results, require us to take into account that inactive chronic hepatitis could be reactivated by further toxic insult. A teratology study demonstrated increased number, body weight and length of fetuses, without apparent pathological events (tumors, external malformations). A mutagenicity test performed on rat femoral bone marrow after 30-days feeding of 37.5 mg kg-1 did not indicate any significant change in the incidence of chromosomal aberrations, compared with the control group. The recommended maximum allowable concentration in the working zone for thiophosphoryl chloride in air was set at 3 mg m-3.

Abnormalities, Drug-Induced↗
PubMed1989

[Inhalation exposure to welding fumes of arc welders in processing Cr-Ni steel in large chemical industry].

For clearing up the inhalative load by welding fumes and gases of arc welders in industrial workshops mainly working on Cr-Ni-steels the following welding processes were studied: tungsten inert-gas (TIG), electrode-by-hand (EH), metal inert-gas (MIG), and plasma cutting (plasma). From the total load by welding fumes follows the rank TIG less than EH less than plasma less than MIG. Observing the maximum allowable concentration (MACD) for the total welding fume, no MACD for Cr and Ni was found exceeded. Regarding the welding gases ozone and CO no limit values were exceeded. From the results conclusions were made.

Air Pollutants, Occupational↗
PubMed1978

Styrene, its metabolism and the evaluation of hazards in industry.

The main products of styrene biotransformation excreted in human urine are mandelic and phenylglyoxylic acids. Phenylethylene oxide seems to be the first metabolite; this compound has been reported to be mutagenic and carcinogenic. The polarographic determination of mandelic acid has been used for about 20 years in Czechoslovakia as an exposure test for persons occupationally exposed to styrene. Only single cases of health damage have been reported to be due to styrene exposure during this time. Recently, however, elevated frequencies of chromosomal aberrations in peripheral lymphocytes have been observed in persons exposed to styrene in Czechoslovakia. The amount of phenylethylene oxide that can be formed in the human body during exposure to 50 ppm of styrene in air during a workshift is about 0.7 g. It would be hardly justifiable now to believe that styrene is not carcinogenic and mutagenic in man. The present Czechoslovakian maximum allowable concentration of styrene (200 mg/m3) should be reduced, and the concentration of 50 mg/m3 may be recommended as reasonable at this time. The corresponding biological limit value of mandelic acid might be 300 mg/l of urine from the last 2 h of the workshift.

Air Pollutants↗
PubMed2000

Polish system of assessing occupational risk posed by chemical compounds.

According to the Polish Labour Code &elpar;Ustawa, 1974) employers are legally obligated to provide workers with information about occupational health and safety risks. Maximum allowable concentrations (MAC) and the results of determining chemical compounds in workplace air are used for assessing occupational exposure and risk. A computer-assisted system STER, developed in the Central Institute for Labour Protection, helps to register and document occupational risk assessment and all actions resulting from those assessments.

Air Pollutants, Occupational↗
PubMed1995

Strategy of biological monitoring and setting of biological threshold limits (BAT values) in Germany.

Biological monitoring is of fundamental importance in Germany. The successful strategy of biological monitoring is based on four factors. Recommendations for the pre-analytical phase have been issued by official societies. For the analyses in blood and urine specimens around 100 methods have been recommended and standardized. All measurements must be carried out under a quality control scheme issued by the German Ministry of Labor and organized by the German Society of Occupational and Environmental Medicine. The occupational medical judgement of the biological monitoring results take place by "Biological Tolerance Values for Working Materials" (BAT values) and "Exposure Equivalents for Carcinogenic Working Materials" (EKA values). A BAT value is, by definition, the maximum allowable concentration for an individual which should be exceeded; 53 BAT values for 37 agents or groups of agents and 18 EKA values for 10 compounds have been defined. These values have been published since 1982 in an annual list of occupational standards. Every BAT or EKA value is based on extensive scientific documentation.

Environmental Monitoring↗
PubMed1983

A relationship between toxicity and chemical nature.

The maximum allowable concentration of any chemical substance can be estimated with some degree of confidence solely on the basis of the chemical groups and structure it contains. The derivation of this methodology from the U. S. Dept. of Labor Occupational Health and Environmental Control Air Contaminants List (1972) is described.

Animals↗
PubMed1993

The setting of an occupational exposure limit for phosphamidon in the workplace--a Chinese approach.

This paper describes the approach of setting an occupational exposure limit for phosphamidon, an organophosphorus pesticide, in the workplace in China. Apart from a general review of the literature relating to various toxicological studies, special emphasis has been placed on the results of a systematic occupational health survey on the workers exposed to phosphamidon. As a result of the survey, together with the literature review, a 'maximum allowable concentration' (MAC) for phosphamidon in the air of workplace is suggested as 0.02 mg m-3 but on the condition that the route of skin entry be blocked effectively. In addition, based on the description of the standard-setting process in China, a comparison has been made to the current U.K. approach.

China↗
PubMed1999

[Pesticide bioaccumulation: measurement and levels of organochlorine residues in products of vegetable origin].

Because of their lipophilic properties and their persistence, organochlorine pesticides residues can be accumulated in human body by consuming regularly plants products. This study consisted of the monitoring of the contamination level of pesticides residues from various plants products, in order to assess the long- term intoxication risk to which Senegalese consumer is exposed ant identify throughout these plants some indicators of atmospheric pollution. The chromatographic analysis of medicinal plants, fruits and vegetables extracts showed that they could be contaminated by organochlorine residues. About ten of these pesticides residues were found confirming that the analysed plants were really contaminated. The residues level in medicinal plants (from 0.1 to 45 micrograms/kg) were widely below the maximum allowed concentrations and were also lower than those in fruits and vegetables (from 0.1 microgram/kg to 460 micrograms/kg). Heptachlorine residues contents of tomatoes and citrus fruits were higher than FAO/WHO norms, so that, a regular monitoring of the plants products is recommended for better protection of consumers.

Chromatography, Gas↗
PubMed1993

Urine, serum and hair monitoring of hydrofluoric acid workers.

To define the relationship between fluoride (F) concentration in the serum, urine and hair of workers and the concentration of hydrofluoric acid (HF) in the work environment, pre- and postshift serum and urine samples of 142 HF exposed workers and 237 unexposed workers were examined. Hair specimens were also collected for the determination of F. To determine whether external contamination influences hair analysis, the control hair samples were kept in the work environment for one week. The pre-exposure levels in serum and urinary F in HF workers were higher (P < 0.01) than the control values. This suggests that F excretion from the body continues for at least 12 hours. The postshift serum and urinary F concentrations of these workers were significantly higher (P < 0.01) than the preshift concentrations. The levels of F in the hair of HF workers were also higher than in the control subjects. The concentrations of F in postshift serum and urine, and hair were in good correlation to each other. There was a linear relationship between mean serum and urinary F concentrations and HF concentration in the workplace. A mean F concentration of 82.3 micrograms/l in serum and 4 mg/l in urine with a lower fiducial limit (95%, P = 0.05) of 57.9 micrograms/l in serum and 2 mg in urine were estimated to correspond to an atmospheric HF concentration of 3 ppm, which is the maximum allowable concentration recommended by Japan Association of Industrial Health and also the threshold limit value suggested by American Conference of Governmental Industrial Hygienists.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Experience in controlling lead poisoning in the People's Republic of China.

This paper summarizes the work done to control lead poisoning in the People's Republic of China. The work can be divided into the following four phases: (i) health surveillance of lead workers, (ii) health standard setting, (iii) research for early detection indicators, and (iv) improvement of the work conditions and health surveillance of "undeserved" groups. In 1949 prevention started with the initiation of the health surveillance of lead workers. Since then health surveillance has been used to supplement environmental monitoring in the early detection of lead poisoning, and the prevalence of lead poisoning has decreased. This activity has also helped to identify the needs for improvement in technological control. The next step has been the promulgation of health standards. The current standard for lead gives the maximum allowable concentration in air as 0.03 mg/m3 for lead fume and 0.05 mg/m3 for lead dust. Research on indicators for the early detection of lead has improved the quality of prevention. It has recently led to the addition of zinc protoporphyrin to the list of indicators in use. Finally the work conditions and surveillance of workers that had earlier been considered "underserved," particularly workers in agriculture and small industries in rural areas, are being improved.

China↗
PubMed1998

Updating of hygiene standards for carbon disulfide based on health risk assessment.

In 1995 the hygiene occupational standard values of carbon disulfide (CS2) were established in Poland: the maximum allowable concentration, eight-hour time weighted average (MAC-TWA)--18 mg/m3, and the short time exposure level (STEL)--30 mg/m3. For lack of reliable retrospective data on the CS2 exposure levels in the work environment and the dose-response relationship, the following have been taken into account in establishing these values: the nervous and vascular systems are recognized as the main CS2 exposure targets; long-term exposure to CS2 in the work environment, exceeding 30 mg/m3, induces the toxic effect in the nervous and cardiovascular systems; chronic exposure to CS2 at concentration below 20 mg/m3 does not produce adverse effects in the peripheral nervous and vascular systems; coronary heart disease does not occur more frequently in workers exposed to CS2. Aiming at updating the 1995 MAC value for CS2 the authors carried out an analysis of the recent literature data on the relation between exposure levels and health risk. The results of clinical and epidemiological studies published in 1995-1997 did not provide evidence that adverse health effects in the cardiovascular and neurological systems in persons occupationally exposed to CS2 at concentration below 48 mg/m3 is likely to occur. The studies of the harmful effects of low CS2 concentration on the reproductive system have not proved that CS2 affects the embryo and fetus. Moreover, in Poland the employment of women under conditions of CS2 exposure (regardless of concentrations) during pregnancy and breast feeding is banned. Because the latest reliable studies have not indicated that chronic CS2 exposure at the level of 20-48 mg/m3 exerts toxic effect on humans, CS2 concentration of 18 mg/m3 as MAC-TWA and 30 mg/m3 as STEL, adopted in 1995, need not to be updated.

Aged↗
PubMedDate not supplied

[The methodology for the rapid experimental validation of hygienic standards for xenobiotics in different environments].

Correlation- and regression analyses were carried out of relatedness of industrial chemical substances and pesticides LD50 (LC50) to their maximum allowable concentration in the air of the working environment and permissible diurnal doses in enteral route (according to the standard basis of the nineties). Highly reliable regression equations have been derived, which can be made use of in practice provided acute and subacute experiments aimed at determining LD50 (LC50) and complex (qualimetric) assessment of cumulative properties of the studied substances will be carried out.

Animals↗
PubMed1979

Toxicological studies of shale oils, some of their components, and commercial products.

Estonian shale oil contains about 25--30% phenols, and their action determines the toxicity of shale oils. The clinical symptoms of intoxication are rather similar, regardless of route of administration. Due to neurotropic action, the coordination of movements is impaired, and clonic and tetanic convulsions, paresis and paralysis of extremities, and narcosis are observed. In subacute and chronic toxicity tests, dysfunction of the central nervous system was found. In long-term (4--6 month) experiments, changes in liver and kidney function were found. Shale oil has gonadotropic activity and causes changes in the sexual cycle as well as diminution of the number of primordial folicles in the ovaries or a decrease in the quantity of normal spermatogonia in testicular germinal epithelium. Shale oils produce local irritation of skin and mucous membranes. Shale oil can induce sensitization of the organism after repeated administration. The results of acute intoxication tests have proved that volatile and nonvolatile phenol fractions, isomeric dimethylphenols, and 5-methylresorcinol, must be characterized as moderately toxic substances; the LD50 ranges from 501 to 1500 mg/kg. The clinical symptoms of acute toxication are similar for all studied phenols (restlessness, unsteadiness, clonic tremor, paresis and paralysis of extremities, and death). In spite of the moderate toxicity of phenols in acute experiments, repeated administration of small doses can cause different changes in the nervous system and internal organs of experimental animals. For all the phenols studied, the maximum allowable concentration in water was limited by their effect on the organoleptic properties of water. The nonactive dose for warm-blooded animals is from 100 to 3000 times the threshold limit value of phenols on the basis of their organoleptic properties. The effect of commercial products of oil shale industry is generally determined by the toxicity of the main components: water-soluble oil shale phenols.

Animals↗
PubMed1995

[Amorphous silica. Types, health effects of exposure, NDS].

Maximum allowable concentration (MAC) values for amorphous silica dust have not been identified in the Polish legal regulations up-to-date. In this work the authors review values of allowable (recommended) amorphous silica dust concentrations in other countries. Data on other types of amorphous silica (natural and synthetic) used in industry as well as data on health effects of exposure to these types of dust are presented. The work encompasses 42 entries in the references and one Table which includes the following proposed MAC values: Non-calcinate diatomaceous earth (diatomite) and synthetic silica: Total dust--10 mg/m3 Respirable dust--2 mg/m3 Calcinate diatomaceous earth (diatomite) and fused silica (vitreous silica): Total dust--2 mg/m3 Respirable dust--1 mg/m3.

Diatomaceous Earth↗
PubMed1975

Carbon monoxide in school buses.

Following an incident in which eight children became ill from carbon monoxide in a school bus, an investigation was made of CO levels in school buses in the Seattle area. The procedure selected for the evaluation was to test a large number of buses at a nearby ski resort. On the day selected for the sampling, over 200 buses arrived, bringing school children from a number of school districts in the Seattle are for skiing lessons. As they arrived, 33 buses were checked immediately to determine in-transit levels of CO. Four of the 33 buses had CO levels in excess of Environmental Protection Agency maximum allowable concentrations for an 8-hr exposure. As the buses sat idling in the parking lot, 65 of them were tested--during the lunch hour when the students returned to the buses to have their lunch and to rest. Two buses had nearly 3 times the concentration of CO permitted by the EPA for a 1-hr exposure. A total of seven buses (10 per cent) had concentrations of CO not permitted by the EPA for more than a 1-hr period. Altogether there were 24 buses (36 per cent) that had levels of CO in excess of EPA standards for an 8-hr exposure. As a result of these determinations and other observations a number of recommendations were made to reduce the hazard of exposure to carbon monoxide in school buses.

Air Pollutants↗
PubMedDate not supplied

[Assessment of health risks upon exposure to methylated mercury].

Accumulation of a toxic agent (2-4-fold maximum allowable concentrations) was found in the fish caught in the polluted area of the water storage basin of the Angara river. The authors quantified a risk for major pathological syndromes in individuals exposed to mercury on fish ingestion and assayed biosubstrates for the substance. The integral risk of major pathological syndromes in the potentially mercury loaded persons increased by 62.1% with age and only by 17.1% in the control group. In the risk pattern there were risks for neurological diseases, arterial hypertension, coronary heart disease, borderline mental disorders, and endocrine diseases.

Adolescent↗
PubMed1985

Research results of Soviet scientists in some problems of occupational medicine. Review of the years 1981-1984.

The paper reviews the extensive and manifold research of Soviet scientists in occupational medicine. Monographs published in 1981-1984 have been referred to. The data on the maximum allowable concentrations of 23 substances are presented. It should especially be emphasized that, at present, great attention is being paid in the Soviet Union to the mutagenic, gonadotoxic and embryotoxic, as well as other biological, effects of the substances under study. A short review has been presented of the research dealing with the setting of standards for substances coming in contact with the skin of the hands. Occupational hygiene aspects of problems related to the introduction of new substances and technological processes have been considered, and research on the effects of harmful factors (toxic substances, vibration, etc) on health and the early diagnosis of occupational pathology has also been reviewed.

Animals↗