Safe Levels of Industrial Poisons for Man

Maximal permissible concentration or dose for man with using coefficient of safety depending on level of poison toxicity, cumulation, etc. is calculated on the basis of Lim ch (NOAEL) for animals.

Key Parameters of Toxicokynetics

They are as follows:

Т50 - the half-life period of poison in organism (in blood, organs, biological liquids);

Т95 - the period of elimination of 95% of poison from organism.

It is determined in experiments with the help of radioactive labels (isotope C14).

The less these parameters are, the faster poison is eliminated from organism.

Toxicokyneticsis closely connected with cumulation of poisons in organism.

 

Table 39

Basic Parameters of Toxicometry of Chemical Substances

Primary parameter	Derivative parameter
Parameters of Toxicodynamics
1. Acute toxicity
Lethal doses and concentrations LD0, LD50, LD100 (LC)	Zone of lethal effect Z = LD84 / LD16
Factor of specific sensitivity FSS = LD 50 max/LD 50min	Factor of probability of inhalation poisoning FPIP = C/LC 50
Threshold of acute integrated effect Lim ac. integr. Threshold of acute specific effect - Lim ac. sp.	Zone of acute effect Z ac. = LD 50/Lim ac. integr. Zone of acute specific effect Z ac.sp. = LD 50/Lim ac. sp.
2. Subacute toxicity
Factor of cumulation F cum. = LD 50 total for 30 days/LD 50 single Threshold of subacute effect Lim s/a eff.
3. Chronic toxicity
Threshold of chronic integrated effect Lim ch. Integr. (LOAEL) * Threshold of chronic specific effect Lim ch.sp.	Zone of chronic effect Z ch. = Lim ac/Lim ch.   Zone of biological effect Z ch.sp. = Lim ac.sp./Lim ch.sp.
Safe levels for man
Maximal non-effective dose (NOAEL) *, MPC
Parameters of Toxicokinetics
The half-life period of substance in organism - Т50 The period of elimination of substance from organism - Т95 Factor of cumulation - F cum.

*LOAEL - low-observable adverse effect level

*NOAEL - non-observable adverse effect level

Classification of Industrial Poisons

Classification of Chemical Substances according to Toxicity

I class of danger – extremely dangerous substances (extremely toxic)

II class of danger - highly dangerous substances (highly toxic)

IIIclass of danger - moderately dangerous substances (moderately toxic)

IV class of danger - slightly dangerous substances (slightly toxic)

 

Table 40

Parameter	I class	II class	III class	IV class
MPC in air, mg/m3	< 0.1	0.1 – 1.0	1.0 - 10	> 10
DL50 orally	< 15	15 - 150	150 - 5000	> 5000
DL50 on skin	< 100	100 - 500	500 - 2000	> 2000
CL50 inhalation	< 500	500 - 5000	5000-50000	> 50000
FOIP	> 300	300 - 30	30 - 3	< 3
Zone of acute effect (Z ac.)	< 6	6 - 18	18 - 54	> 54
Zone of chronic effect (Z ch.)	> 10	10 - 5	5 – 2.5	< 2.5

Classification of Poisons according to Primary Effect on Organism

They are subdivided into irritating, neurotropic, cardiotropic, hepatotropic, nephrotropic, gonadotropic, cancerogenic, mutagenic, etc.

Basic Mechanisms of Poison Effect on Organism

Toxic effect of poisons depends on:

v Exogenous factors:

Ø Chemical structure of poison (for example, increase of toxicity in homological line of hydrocarbons);

Ø Dose, concentration of poison (dependence "dose - effect" and "time - effect");

Ø Volatility, level of dispersion of poison;

Ø Way of entry into organism (inhalation or others); character and rate of metabolism, way of eliminating poison from organism;

Ø Conditions of environment (meteorologic factors);

Ø Selective sensitivity: age-related, sexual, specific, individual;

Ø Selective effect on organs and systems:

§ Commom toxic poisons

§ Hepatotropic

§ Nephrotropic

§ Cardiotoxic

§ Neurotropic

Ø Character of effect:

§ Constant or intermittent

§ Isolated

§ Combined, complex

v Endogenous factors depending on state of organism:

Ø Age

Ø Sex

Ø Presence of diseases

Ø Defects of detoxication system (inherited or acquired)

Ø Pregnancy, lactation

Ø Physical and mental overstrain.