MAC of harmful substances is the permissible value of a polluting chemical compound contained in soil, water or air, which does not affect - directly or indirectly - harmfully on living organisms. Values in appropriate units are determined by toxicological studies.
Characteristics of MPC as a meter
What is MPC in environmental regulation? This is the main indicator of industrial ecology, which all manufacturing enterprises are guided by. The MPC values of substances are derived and distributed according to the type of chemical structure and toxicological effects on living organisms. GOSTs have been created, compliance with which is mandatory.
Depending on the environment in which harmful substances are found, MPC is measured in:
- mg/dm3 – for measurements in the hydrosphere;
- mg/m3 – for measurements in atmosphere and workspace air;
- mg/kg - to determine the indicator in the soil.
When deriving the MPC value, the detrimental effect not only on humans, but also onall living organisms in general. Compliance with established norms allows you to save the entire ecosystem, and not individual species of flora and fauna.
Classification
Maximum concentration limit of harmful substances, depending on the degree of impact on living organisms, is divided into 4 hazard groups:
- I class - extremely dangerous.
- II class is very dangerous.
- III class is dangerous.
- IV class - moderately dangerous.
Depending on the belonging of a pollutant to hazard groups, its MPC and the time spent in the environment of living organisms in the presence of chemical compounds change.
Varieties of MPC
Depending on the environmental assessment criteria, several MPC values have been derived.
For industrial zones allocate:
- MPKr.z. - used to assess the sanitary condition of the atmosphere of the working area. The work area is the space in which the workers are located during the performance of the task, including 2 meters above the level of the site. The coefficient expresses the amount of pollutant in the air that does not cause any deviations in human he alth for several decades.
- MPCp.p. - allocated at industrial enterprises or at a separate site. Usually, the value is taken as 0.3 MAC.z.
For the urban area, there are other standards for the ecological state of the atmosphere, which is determined by the following coefficients:
- MPCn.p. - total allowable valuepollutant in the atmosphere of the settlement. Separately, the coefficients of average daily and maximum one-time pollution of the environment are distinguished.
- MPCm.r. - the amount of pollutant in the atmosphere of an urban area in the maximum expression, which is permissible for a single inhalation. The coefficient is calculated in such a way that the substance does not cause a reaction to chemical irritants during short-term exposure (no more than 20 minutes).
- MPCs.s. – regulates the amount of harmful substances in a concentration that does not have a detrimental effect on human he alth, provided that it is inhaled around the clock.
It should be understood what the MPC of the working and urban space is. MPKr.z. calculated based on the following input data:
- he althy adults are in a polluted environment;
- time of stay is limited by job description and usually does not exceed 8 hours.
Harmful substances in the atmosphere of a settlement affect every inhabitant: an adult or a child, sick or he althy, while it is around the clock and continuously throughout life. As a result, for the same pollutants, significantly different values of maximum permissible concentrations can be determined. Usually, the MPC coefficient of substances in the air of the working area is much higher than the MPCn.p.
Determination of MPC values in water and soil
What is MPC of water bodies? This is the established standard for the concentration of a pollutant per 1 liter of water. Coefficient values are determined separately for each typereservoir. There are waters for fishery, drinking and domestic purposes.
Determining the MPC of pollutants in the soil is the most difficult task. The calculation is made on the basis of soil properties and the chemical nature of harmful substances. Values are always different and tabular values have not been derived for each pollutant.
Distribution of MPC by nature of impact
What is the MPC of chemical compounds, if each substance can act differently?
For a systematic classification of harmful chemicals, several groups are distinguished according to the characteristic signs of impact on a living organism, in particular humans:
- general toxic;
- irritating;
- sensitizers;
- carcinogens;
- mutagens;
- affecting reproductive he alth.
Each of the groups has specific signs of poisoning, validity periods and derived MPCs.
Pollutants with general toxic effects
General toxins cause severe poisoning of the body as a whole. The most obvious violations are noticeable from the side of the human nervous system: convulsions, disorders of consciousness, paralysis occur. The group of substances of general toxins includes aromatic hydrocarbons and their nitro- and amide derivatives, organic compounds with phosphorus, chlorine, as well as some inorganic substances.
The most common ones are:
- arsenic and itsconnections;
- benzene, toluene, aniline, xylene;
- dichloroethane;
- Hg;
- Pb;
- carbon monoxide (IV).
Infection with many of the substances occurs not only at work, but also at home.
MAC in the atmospheric air of general toxic substances
Consider the indicators of the average daily and single MPC in the air of the urban and working areas. For convenience and clarity, the information is presented in the form of a table.
| Substance | hazard class | MPCd, mg/m3 | MPC, mg/m3 | MPC, mg/m3 | Impact |
| Xylene | Third | 0.19 | 0.18 | 50 | Affects the cardiovascular system, liver, kidneys, skin |
| Benzene | Second | 0.09 | 1.5 | 15/5 | Causes disorders of the nervous system, bone marrow functions, exhibits carcinogenic properties |
| Toluene | Third | 0.59 | 0.058 | 50 | Causes disorders of the nervous and cardiovascular systems |
| Lead and its compounds | First | 0.00029 | – | 0.009–0.45 | Detrimentally affects the central nervous system, heart, liver, causes endocrine disorders, deaths of poisoning are not uncommon. Refers to general toxic substances, as well as carcinogens and mutagens. |
| Nitrobenzene | Fourth | 0.004 | 0.2 | 3 | Affects blood and liver |
| Mercury and its compounds | First | 0.00029 | – | 0.19–0.48 | Affects the nervous, immune and digestive systems |
| Dichloroethane | Second | 1 | 3 | 10 | Destroys the liver, kidneys, is a narcotic substance |
The average daily concentration of harmful substances implies interaction with the human body for several years without developing any consequences.
Action of irritating chemicals
Chemical compounds affect the skin, mucous membranes and respiratory tract. The most common irritants are halogens and oxides of nitrogen and sulfur.
| Substance | hazard class | MPCd, mg/m3 | MPC, mg/m3 | MPC, mg/m3 | Impact |
| Chlorine | Second | 0.29 | 0.09 | 0.95 | Irritating to the mucous membranes of the eyes and respiratory tract, inhalation of large doses leads to pulmonary edema |
| Nitrogen dioxide | Second | 0.04 | 0.085 | 2 | Causes chronic lung disease |
| Hydrogen sulfide | Second | – | 0.008 | 10 | Causes damage to the nervous and respiratory systems, often leading to death |
| Sulfur dioxide | Third | 0.48 | 0.49 | 10 | Irritates the lungs, provokes the development of asthma, swelling of the nasopharynx |
Prolonged inhalation of harmful vapors leads to severe respiratory failure, intoxication and death.
Sensitizers and their MPCs in the atmosphere
Substances with a sensitizing effect cause an allergic reaction in humans. Common compounds in this group include aldehydes and hexachlorane.
| Substance | hazard class | MPCd, mg/m3 | MPC, mg/m3 | MPC, mg/m3 |
| Hexachloran | First | 0.029 | 0.029 | 0.09 |
| Formaldehyde | Second | 0.009 | 0.048 | 0.5 |
| Benzaldehyde | Third | – | 0.04 | 5 |
| Propionic aldehyde | Third | – | 0.01 | 5 |
| Croton aldehyde | Second | – | 0.024 | 0.5 |
Sensitizers are released into the atmosphere during fuel combustion and industrial activities. A small amount of formaldehyde is also emitted at home: it is found in many building and finishing materials, furniture.
Carcinogens and mutagens
The most dangerous group of chemical pollutants whose impact on the human body has been underestimated for a long time. Carcinogens andMutagens are potent substances with a long latent period of action. Carcinogens include asbestos, beryllium, benzpyrene, aromatic amines. They provoke the formation of various malignant tumors.
Mutagens provoke changes in the human genotype, which are transmitted to offspring. These include radioactive substances, manganese, lead, organic peroxides, formaldehyde.
| Substance | hazard class | MPCd, mg/m3 | MPC, mg/m3 | MPC, mg/m3 |
| Beryllium and its compounds | I | 0.00001 | – | 0.001 |
| Formaldehyde | II | 0.009 | 0.0049 | 0.48 |
| Benzpyrene | I | 0.000001 | – | 0.00015 |
| Asbestos dust | I | 0.059 (particles per ml of air) | – | 2–6 |
| Aniline | II | 0.029 | 0.045 | 0.09 |
| Dimethylaminobenzene | II | – | 0.0055 | 3 |
| Aziridine | I | 0.0005 | 0.0009 | 0.02 |
| Manganese and its compounds | II | 0.0009 | 0.009 | 0.045–0.28 |
| Cumene hydroperoxide | II | – | 0.007 | 1 |
Many mutagenic substances additionally affect reproductive he alth, these include: benzene and any of its derivatives, lead, antimony, manganese, pesticides, chloroprene and others.
