From Big Medical Encyclopedia

MAXIMUM ALLOWABLE CONCENTRATIONS (MAC) — the hygienic standards regulating environmental pollution, safe for the person, chemical (including radioactive) substances. Maximum allowable concentration — necessary criteria at implementation a dignity. protection of air of a working zone, the atmosphere of the inhabited places, water, the soil and food stuffs. In the USSR for the first time maximum allowable concentration (for hydrogen chloride) it was established and approved as Narkomtrud on August 30, 1922.

As maximum allowable concentration in air of a working zone such concentration of harmful substances which at daily (except the days off) work during 8 hours (or at other duration, but no more than 41 hour a week) during all working experience cannot cause the diseases or deviations in the state of health found by modern methods of researches both during work and in the remote terms of life of the present and succeeding generations are allowed.

Maximum allowable concentration of atmospheric pollution — the maximum concentration of harmful substances referred to certain time of averaging (20 — 30 min., 24 hours, 1 month, 1 year) which at the regulated probability of their emergence do not render either direct, nor indirect harmful action on the person, his posterity and a dignity. living conditions.

Maximum allowable concentrations of harmful substances in water of reservoirs — the maximum concentration which at impact on a human body during all his life do not exert the direct or mediated impact on the state of health of the present and succeeding generations and do not worsen a gigabyte. conditions of water use of the population.

Maximum allowable concentrations of exogenous chemical substances for the soil are established for the prevention of secondary pollution hazardous to health of people of the waters contacting to the soil, air and plants.

For foodstuff there are standards of admissible residual amounts of harmful substances (DOCK). The amount of maximum allowable concentration of harmful substances for air is defined in mg/m3, for water — in mg/l, for food stuffs and the soil — in mg/kg. Establishment of the most one-time and for high-cumulative substances of srednesmenny concentration is provided in air of a working zone, the most one-time and average daily concentration — in free air of the inhabited places. According to GOST 12.1.007 — 76 along with maximum allowable concentration the class of danger of substances (for a regulation of ventilation, planning and hardware registration of technological process), and also aggregate state of substance in actual practice of contact with people is specified (for justification of control methods). The substances capable to get into an organism through the unimpaired skin are designated by a special symbol. For each substance regulated in free air of the inhabited places the class of danger is also proved. Justification of maximum allowable concentration in water is carried out taking into account one of three limiting indicators of harm of substance — organoleptic, all-sanitary or sanitary and toxicological.

Examples of the existing standards of maximum allowable concentration of nek-ry harmful substances in air of a working zone, free air of the inhabited places and water of reservoirs of sanitary and household water use are given in tables 1 — 4.

Maximum allowable concentrations of harmful substances in air of a working zone are established step by step. The first stage is dated for the period of laboratory development of new connections and comes to an end with justification of approximate safe level of influence. The second stage belongs to the period of semi-production tests and design of production. At this stage the maximum allowable concentration in hron, and lifelong is proved (for studying of carcinogenesis, processes of a senilism, etc.) experiments on animals. The third stage begins after implementation of substances in production in the terms established depending on a toxicological property of substance and a gigabyte. characteristics of production, but not later than in 3 — 5 years from the moment of implementation, also consists in specification of maximum allowable concentration by comparison of the working conditions working and a condition of their health.

Staging of establishment of maximum allowable concentration of chemical substances in water of reservoirs following. At the first stage threshold concentration of chemical substances on an organoleptic and all-sanitary sign of harm are established, toxicological researches for calculation of most not operating concentration are conducted. At the second stage subacute animal experiments using an express eksperimen-talnykh of methods and the subsequent extrapolation of the received results on long terms of influence are made. At the third stage are put hron, experiments, and on the fourth — lifelong experiments for the purpose of studying of cancerogenic action and a geroeffekt are made. Depending on a class of danger of the studied substance of a research can be complete for substances of the 4th class of danger at the first stage, for substances of the 3rd class — at the second stage, for substances of the 2nd class — at the third stage and for substances of the 1st class — at the fourth stage.

Maximum allowable concentrations of radioactive materials are designated differently. At internal radiation due to intake of radionuclides in an organism establish the admissible concentration (AC) — the relation of marginal annual receipt (PDP), or the limit of annual receipt (LAR) of radioactive material, to the volume (V) water or air, about the Crimea it comes to a human body within a year. For contacting to sources of ionizing radiation by the nature of the professional activity air volume the equal 2,5-106 l a year are accepted; for persons who do not work directly with sources of radiation, but under the terms of accommodation or placement of jobs can be affected by ionizing radiation, air volume is equal 7,3-106d in a year, and water volume — 800 l a year.

Marginal annual receipt (PDP) — such amount of the radioactive materials coming to an organism of the professional worker within a year a cut in 50 years creates the equivalent dose equal to 1 traffic regulations in critical body (see. Marginal dose of radiation). At annual intake of radioactive material in an organism at the level of PDP the equivalent dose for any year will be equal or less than 1 traffic regulations (depending on time of achievement of equilibrium content of radioactive material in an organism). The Limit of Annual Receipt (LAR) — amount of the radioactive materials coming to an organism of narrow groups of the population within a year a cut in 70 years creates the equivalent dose equal of 0,1 traffic regulations in critical body.

Admissible concentration of radionuclides of rare gases (argon, krypton, xenon) and short-lived radionuclides of carbon, nitrogen and oxygen are calculated proceeding from admissible dosage rate their external beta and gamma radiations. For the majority of radionuclides numerical values of PDP, PGP and recreation center are calculated proceeding from their equilibrium accumulation in critical body equal to admissible contents. During the planning of actions for protection and for operating control behind a radiation situation for the purpose of prevention of exceeding of a dose limit reference levels of receipt in an organism of radionuclides shall be established. Before establishment of reference levels they are accepted equal admissible, established by standards of radiation safety (NRB-76). Admissible concentration of radionuclides are defined in curie/l (for air and water) and in curie/kg (for food stuffs).

Establishment of maximum allowable concentration is based on the principles of an advancing of development of standards to implementation of new chemical connections in the national economy, on a priority of medical indications before technical approachibility at the time of the research of substances and before other technical and economic criteria, on the principle on-rogovosti all types of action of chemical connections (including mutagen and cancerogenic) on a complete organism taking into account need of a comprehensive approach to establishment of thresholds of harmful action. Maximum allowable concentrations are approved by M3 of the USSR, and control of their observance is imposed on bodies and institutions of sanitary and epidemiologic service.

The Approximate Safe Levels of Influence (ASLI) — temporary approximate a gigabyte. the standards limiting the content of harmful substances in objects of the environment (air of a working zone, free air of the inhabited places, water, etc.) for the purpose of providing safe working conditions and life. This concept is entered instead of earlier applied «settlement maximum allowable concentrations» in order to avoid terminological confusion. HAVING PUT are applied at a stage of research and trial development, at a stage of tests of new substances and technological processes. They locate by a settlement way in the parameters of a toksikometriya received as a result of short-term experiments on laboratory animals at single and repeated (up to 1 month) influence, and by interpolation and extrapolations in the series of compounds close on physical, chemical properties and biological effect. HAVING PUT on the majority of methods of justification excludes definition of a threshold hron, effects of substances as most labor-consuming and long part of researches. Sizes HAVING PUT are approved by M3 of the USSR for limited term (for air of a working zone experienced and semi-plants — for 2 years, for free air of the inhabited places — for 3 years) then they depending on perspective of use of substance and the available information on its toxic properties shall be replaced with maximum allowable concentration or pereut-verzhdena for new term or are cancelled.

According to requirements of GOST 12.1.007 — 76 for HAVING PUT control methods in air of a working zone shall be developed. HAVING PUT in free air of the inhabited places can be used for precautionary sanitary inspection (see) in the absence of methods of chemical control.

The concept «threshold limit values» accepted in the USSR differs from the corresponding foreign regulations. So, the concept of «the size of a threshold limit» — Threshold Limit Values (TLV) is widespread in the USA that means average concentration of harmful substances for change. Sizes maximum allowable concentrations and TLV for separate substances sometimes differ in tens of times in connection with distinctions of the principles and methods a gigabyte. rationing. In our country maximum allowable concentrations are established on the basis of these medicobiological researches, and in the USA at justification of TLV this principle is not obligatory.

See also Standards hygienic .



Are brought as an example. Symbols: p — vapors and (or) gases; and — aerosols; p + and — mix of vapors and an aerosol; * — substance is dangerous at receipt through skin; ** — srednesmenny maximum allowable concentration.



Notes. 1. At presence at free air at the same time several substances (e.g., carbon monoxide and sulphurous anhydride; carbon monoxide, nitrogen dioxide and sulphurous anhydride; hydrogen sulfide and carbon sulfur; phthalic, maleic anhydrides and and - naphthoquinone) maximum allowable concentrations remain for each substance separately.

2.       At simultaneous presence at free air of several substances possessing summation of action, the sum of their concentration during the calculation for a below-mentioned formula shall not exceed 1.

C1/PDK1 + C2/PDK2 + … + <Sn/Pdkspan >&lang=EN-USn lt; = 1

where: C1, S2......, &Cnnbsp; — the actual concentration of substances in free air; &Pdk1nbsp; PDK2......, &Pdknnbsp; — maximum allowable concentrations of the same substances.

Have effect of summation: sulphurous anhydride, carbon monoxide, nitrogen dioxide and phenol; acetone, acrolein, phthalic anhydride; acetone, acetophenone, acetone and phenol; acetone, furfural, formaldehyde and phenol; acetic aldehyde and vinyl acetate; aerosols of vanadium pentoxide and oxides of manganese; aerosols of vanadium pentoxide and sulphurous anhydride; aerosols of vanadium pentoxide and trioxide of chrome; benzene and acetophenone; valerian, kapron and oil acids; hexachlorane and fazolon; 2,3-dichlorine-1,4-naphthoquinone and

1,4 naphthoquinone; isopropyl benzene and isopropyl benzene hydroperoxide; ozone, nitrogen dioxide and formaldehyde; carbon monoxide, nitrogen dioxide, formaldehyde, hexane; sulphurous anhydride and aerosol of sulphuric acid; sulphurous anhydride and hydrogen sulfide; sulphurous anhydride and nitrogen dioxide; sulphurous anhydride, carbon monoxide, phenol and dust of converter production; sulphurous anhydride and phenol; sulphurous anhydride and hydrogen fluoride; sulphuric and sulphurous anhydride, ammonia, nitric oxides; hydrogen sulfide also dinit; strong mineral acids (sulfuric, salt and nitric); carbon monoxide and dust of cement production; acetic acid and acetic anhydride; phenol and acetophenone; furfural, methyl and ethyl alcohols; cyclohexane and benzene; ethylene, propylene, butylene and amilen.

3.       At consecutive use of hexachlorane, a fazolon and butifos maximum allowable concentrations of each substance separately remain.

4.       Effect of potentiation hydrogen fluoride and ftorsol with coefficient 0,8 have.


&1nbsp; Are brought as an example.

Symbols:       * —       in       limits,       admissible       calculation on organic content, on indicators of BPK and the dissolved oxygen; ** — dangerously at receipt through skin.

Bibliography: Methods of studying of biological effect of pollutants (the review of the methods used in the USSR), Copenhagen, WHO, 1975, bibliogr.; Moskalyov Yu. I. Some results of the International commission on radiological protection (MKRZ) in 45 years (from 1928 to 1973), in book: From radiobiol. an experiment to the person, under the editorship of Yu. I. Moskalyov, page 253, M., 1976; Standards of radiation safety (NRB-76), M., 1978; The Problem on-rogovostm in toxicology, under the editorship of G. N. Krasovsky, M., 1979; Radiation protection, Recommendations of MKRZ, the Publication-26, the lane with English, M., 1978; With An about c to and y I. V. The prevention of harmful chemical effects on the person — a complex problem of medicine, ecology, chemistry and equipment, Zhurn. Vsesoyuz, chemical about-va of D. I. Mendeleyev, t. 19, No. 2, page 125, 1974, bibliogr.; Sh and c to about - in and A. P., etc. Hygienic rationing in the conditions of scientific and technical progress, in book: The comprehensive analysis of the surrounding environment, under the editorship of Yu. A. Izrael, page 105, L., 1975, bibliogr.

I. V. Sanotsky, K. K. Sidorov, Yu. I. Moskalyov.