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Theme № 19. Industrial toxicology and toxicology of agrochemicals
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THEME № 19. INDUSTRIAL TOXICOLOGY AND TOXICOLOGY OF AGROCHEMICALS
Toxicology and industrial toxicology.
Toxicology is a science, studying laws of action various toxins (poisons) on an organism. The toxicology shares on military, household, industrial.
Industrial toxicology - the section of toxicology, studying laws of action on an organism industrial poisons - chemical substances to which the person contacts on manufacture and which can cause development of professional poisonings.
Parameters toxity of industrial poisons.
For the toxic and hygienic characteristic industrial poisonings it is necessary to know key parameters of it toxity at investigation on laboratory animalsdependences " doze - effect" (TOXICODYNAMICS) and " time - effect" (TOXICOKYNETICS).
All these parameters are determined in experiments at laboratory animals and then approximated on the person with account FSS - factor of specific sensitivity - differences in toxicological parameters for different kinds of warm-blooded animals (white mice, rats, rabbits).
KEY PARAMETERS LEVEL TOXITY POISONS
PARAMETERS OF TOXICODYNAMICS:
1. ACUTE TOXICITY (at unitary influence):
1) Lethal (fatal) dozes (concentration) – LD0, LD100, LD50 (amount in % of animals, died at action of this doze).
2) Threshold (limit) of sharp action - Lim ac. – limit doze on general toxic effects, Lim ac sp. - on specific effects (for example, irritating action).
3) Zone of sharp action - Z ac. = LD50 / Lim ac. – then it is less, the substance is more dangerous for sharp poisonings.
2. HALF-ACUTE TOXITY – it is studied at influence on animals in experiment by 30-45 days. It is determined coefficient cumulation (C. cum. ) = LD50 at unitary action / LD50 totally during 30 days.
3. CHRONIC TOXITY ( at long time influence – during months or years) - it is most important parameter - represents real conditions of influence industrial poisons on the person. Indexes it is investigated on laboratory animal:
Lim ch (threshold chronic action by common toxic and specific and remote effects). Abroad used LOAEL - the bottom level of notice harmful effect (Lim ch), NOAEL - level of not notice harmful effect (under threshold effect).
Zone of chronic action - Z ch = Lim ac / Lim ch - then it is more - the more opportunity occurrence chronic poisonings.
SAFE LEVELS INDUSTRIAL POISONS FOR the PERSON
From Lim ch (NOAEL) for animals calculated maximal permissible concentration or doze for person with using coefficient safety (depends from level toxity poison, cumulation, etc. )
KEY PARAMETERS TOXICOKYNETICS:
Т50 - the period half-removing poison from an organism (from blood, bodies, biological liquids);
Т95 - the period of removing 95% poison from an organism.
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It is determined in experiments with the help of radioactive labels (isotope C14).
The less these parameters - the faster poison are deduced from an organism.
TOXICOKINETICS is closely connected with cumulation poisons in organism.
KINDS OF CUMULATION POISONS IN ORGANISM
1. MATERIAL - accumulation poison or it metabolites in an organism
2. FUNCTIONAL - accumulation only toxic effects poison in an organism
3. MIXED - accumulation in organism metabolites or poison and pathological effects
CLASSIFICATION TOXIC SUBSTANCES BY DEGREE OF CUMULATION _______________________________________________________
Level cumulation Coefficient cumulation C cum.
Supercumulation < 1
Expressed cumulation 1 - 3
Middle cumulation 3 - 5
Weak cumulation > 5
CLASSIFICATION CHEMICAL SUBSTANCES ON TOXITY
I class of danger - EXTREMELY DANGEROUS SUBSTANCES (Extremely toxic)
II class of danger - HIGLY DANGEROUS SUBSTANCES
(Highly toxic)
III class of danger - MIDDLE DANGEROUS SUBSTANCES
(Middle toxic)
IV class of danger - SMALL DANGEROUS SUBSTANCES
(Small toxic)
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Parameter I class II class III class IV class
MPC in air, mg / m3 < 0, 1 0, 1 - 1, 0 1, 0 - 10 > 10
DL 50 peroral < 15 15 - 150 150 – 500 > 5000
DL50 at skin < 100 100 - 500 500 - 2000 > 2000
CL 50 inhalation < 500 500 - 5000 5000-50000 > 50000
FOIP > 300 300 - 30 30 – 3 < 3
Zone acute action Z ac. < 6 6 - 18 18 - 54 > 54
Zone chronic action Z ch. > 10 10 - 5 5 - 2, 5 < 2, 5
Classification poisons by primary character of action on organism:
Irritating, neurotropic, cardiotropic, hepatotropic, nephrotropic, gonadotropic, cancerogen, mutagen substances.
BASIC LAWS ACTION POISONS ON ORGANISM.
Toxic effect of poisons depend from:
1) EXOGEN FACTORS:
- Chemical structure of poison (for example, increase toxicity in gomological line of hydrocarbons);
- Doze, concentration of poison (dependence " doze - effect" and " time - effect" );
- Ability to flying, level of dispersion of poison;
- Way of receipt poison in organism (inhalation or other); character and rate of a metabolism, path of removing poison from an organism
- Conditions of environment (metheorologic factors);
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- Selective sensitivity: Age, Sexual, Specific, Individual
- Selective activity on bodies and systems:
- Commom toxic poisons
- Hepatotropic
- Nephrotropic
- Cardiotoxic
- Neurotropic
- Character of action:
- Constant or intermittent
- Isolated
- Combined, complex
2) ENDOGEN FACTORS - depends from a state of an organism:
- Age, Sex, Presence of diseases, Defects detoxical system (inheritable or acquired),
Pregnancy, lactation, Physical and intellectual overfatigue.
KINDS ADAPTATION ORGANISM TO ACTION POISONS
ADAPTATION is the true adaptation of an organism to action of poison without irreversible biological changes and with preservation gomeostasis (constancy) biological system.
COMPENSATION (or accustoming) - temporarily latent pathology due to overstrain of adaptable reserves, at action any adverse factors becomes decompensation - poisoning.
In experiment on animals difference of adaptation from compensation is checked by special functional tests.
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