Types of Hygienic Standards in Atmospheric Air

By their effect on organism the atmosphere pollutants are subdivided into 3 groups:

· Substances of the reflex (irritating) action

· Substances of the absorption (toxic) action

· Substances of the reflex-absorption action

There are 2 types of maximal permissible concentration of atmosphere pollutants:

· Maximal–single permissible concentrations (MPC m.s.) are designed for a 20-30-minute effect of irritation pollutants and directed at prevention of reflex reactions and poisonings in people at high concentration of pollutants in air (emergencies). They are established by irritating action on mucous membrane of the eye and by toxic effect. For toxic substances such researches are carried out on animals with transfer of the data on a human being.

· Daily average maximal permissible concentrations (MPC d.a.) are designed for absence of pathological changes in people at a twenty-four-hour effect during the whole life, and also for absence of remote effects in the subsequent generations. MPC d.a. is much lower than MPC m.s. in view of greater exposure (time) to effect.

The criteria of harmful effect at normalization of pollutants in atmospheric air are as follows:

· organoleptic(determining the threshold concentration of pollutant by change of smell, colour, transparence of air);

· reflectory(establishing the threshold concentration by irritating olfactory effect on a human or laboratory animal);

· toxicological(threshold concentration is established by common toxic, specific or remote effects at inhalation on laboratory animals).

Normalization of Pollutants in the Air of a Working Zone

Air of a working zone is the air of industrial and other premises, which pollution affects the workers. At normalization the term of effect is estimated for 40-50 years (the maximal work experience), therefore the maximal permissible concentration of pollutants in the air of a working zone is a bit higher than the maximal permissible concentration in the atmospheric air. At normalization of substances in the air of a working zone the possibility of the skin-absorptive effect on organism is also studied in experiments on animals.

Normalization of Harmful Substances in Reservoir Water

Normalization of pollutants in water depends on type of water use, i.e. drinking, household, recreational, balneological, industrial, fishing, meliorative, transport. Depending on type of water use, various criteria of harm action are applied, therefore the maximal permissible concentration for the same substance can differ considerably. Hygienic standards are established for first four types of water use.

At hygienic normalization of substances in reservoir water the following 3 signs of harmful effect are studied:

· organoleptic(threshold concentrations changing organoleptic properties of water)

· common sanitary(threshold concentrations affecting the saprophytic microflora, oxygen regulations of reservoir, providing the processes of autopurification of reservoir from pollution)

· toxicological (determination of threshold and non-effective concentrations of substance in experiments on animals as for toxic, specific and remote effects).

Hygienic Normalization of Harmful Substances in Foodstuffs

As standards of pollutants in foodstuffs the MPC and MPL (maximum permissible — level — for pesticides in foodstuffs) are used. For substantiation of MPC in foodstuffs very difficult researches are required, that is why maximal permissible concentrations are established only for few substances for the time being.

The characteristic feature of normalization of pollutants in foodstuffs is that MPCs are established in view of PDD value (permissible daily dose of harmful substance entering the organism), thus the entry of pollutant into organism not only with foodstuffs, but also with drinking water and air are taken into account.

Signs (Criteria) of Harmful Effect at Normalization of Pollutants in Foodstuffs

· Organoleptic — effect on organoleptic properties of foodstuffs;

· Hygienic — maintaining the nutritional value, i.e. major nutrients — proteins, fats, vitamins, etc.;

· Technological — transformations of pollutant at culinary (thermal) processing of product, the formation of more toxic metabolites;

· Toxicological — studying toxic, specific and remote effects at introduction into laboratory animals.

Hygienic Normalization of Exogenous Chemical Substances (ECS) in the Ground

ECS are substances of anthropogenic origin, purposely (pesticides, fertilizers) or accidentally (heavy metals, mineral oil, etc.) brought to the ground by a person.

The ground is a burial place of waste products and at normalization of ECS it is necessary to keep processes of autopurification, and also to prevent pollution of subsoil waters and atmospheric air.

Maximal permissible concentration of ECS in the ground is such content of pollutant in the ground, which at direct contact with a human organism (work on the ground) or at migration on ecological chains guarantees absence of negative effect on a human health, does not disturb the processes of ground autopurification and does not influence the sanitary living conditions of the population.

The Basic Signs of Harmful Action at Normalization of ECS in the Ground

· Organoleptic — change of organoleptic properties of air, subsoil waters, vegetable foods contacting with ground, containing various concentrations of normalized substance.

· Common sanitary — effect on the ground microflora and processes of its autopurification.

· Phytoaccumulative (translocative) — accumulation of normalized substance in vegetable foods (not higher than maximal permissible concentration for foodstuffs).

· Air-migratory — evaporation of substance in atmospheric air above the ground (not higher than MPC for air)

· Water-migratory — accumulation of substance in subsoil waters (not higher than MPC for water).

· Toxicological — by toxic, specific and remote effects on laboratory animals at skin or inhalation action together with a soil dust.

 

 

Hygienic Estimation of Objects of the Environment at Combined Pollution

In a real life a human organism is affected, as a rule, not by a single but by a number of harmful factors and their combined effect may considerably differ from a separate effect of each factor. The following types of combined effect are distinguished:

· A combined effect is a simultaneous action on organism of some factors of identical nature, for example, only physical (noise and vibration), or only chemical (chemical substances).

· An associated effect is action on organism of some factors of different nature, for example, chemical materials and radiation effect.

· A complex effect — a harmful factor affects the organism in different ways simultaneously (for example, with inhaled air, nutrition, water, penetrates through skin).