Industrial toxicology is the scientific and systematic study of poisonous substances or toxics
with reference to industries. In industries the workmen may have to face chemical hazards of
toxic nature in their work places. The toxic effect may be fatal or may impair or damage the
human system in the long-run through cumulative action. The toxic of substances depends on
the degree of exposure. In general the degree of exposure depends upon the time of exposure,
the concentration of toxic substance as well as the susceptibility of the workers to a particular
toxic chemical. Toxic may find entry into the human system broadly in a four-fold manner:
1. Through absorption by skin.
2. Through the respiratory system by inhalation.
3. Through the gastro-intestinal tract by swallowing.
4. Through other organs like eyes etc.
Effect of toxic substances on the human system
Effects of toxic substances so far as their degree of danger, sphere of action and exposure-
periods are concerned may be expressed by using suitable terms. The degree of danger
associated with a toxic chemical may be expressed as serious, moderate or mild. Depending
upon the severity of the toxicity hazard. The sphere of action associated with a toxic chemical
may be expressed as local or systemic. A particular part of the body say eyes may be affected
due to exposure of eye to ammonia. This is an example of local effect, whereas lead
poisoning affecting blood forming cells, bones and nervous system is an example of systemic
effects. The exposure- period associated with a toxic chemical may be instantaneous or
prolonged in respect of time. Injured of limbs by corrosives like nitric acid is an example of
instantaneous cases, whereas silicosis resulting from inhalation of silica dust over a long
period of exposure is an example of prolonged case.
Factors influencing the Effects of toxic Materials
The effects of toxic substances on the workmen depend upon the following considerations:
1. Absorption. The effects are dependent upon the rate of absorption of toxic
substances in the human body. Quicker the absorption more is the risk to the
workmen.
2. Concentration and time of Exposure. More the concentration and time of
exposure more is the amount of toxic substances getting entry into the human
body.
3. Personal tolerance level. Certain persons can reasonably tolerate a particular
toxic substance while others cannot.
4. Susceptibility. Susceptibility to toxic substance may vary from person to person.
5. Personal hygiene and behaviour. Personal hygiene and behaviour including
proper maintenance of clothing, cleanliness, tidy habits etc. play an important role
as regards the effects of toxic substances on the human system.
6. The state of the matter. The state of the matter of toxic substances (whether
solid, liquids or gases) play an important role in connection with the effects of
toxic substances on the human system. As for example hydrochloric acid HCI as
(liquid) stored in container will be much less disturbing as compared to an
atmosphere charged with hydrogen chloride (HCI) in the gaseous state.
Some toxic chemicals and their harmful effect on human system
1. Carbon monoxide. Carbon monoxide on inhalation causes asphyxia or
breathlessness. In high concentrations carbon monoxide can also cause death.
2. Carbon disulphide. On inhalation causes anaesthetic effects. Central nervous
system is also affected on prolonged exposure to carbon disulphide.
3. Chlorine. Inhalation causes irritation to mucous membranes i.e. eye, nose etc. it
can cause death if the concentration is high.
4. Chromium. Chromium entering the body through inhalation or taking of food and
water contaminated with chromium compounds can cause ulcers as well as cancer
of certain vital organs of the body as for example lungs etc.
5. Mercury. Mercury and its compounds can cause adverse effects on the central
nervous system of the human body.
6. Lead. Lead poisoning badly affects the central nervous system as well as bones.
7. Naphtha. Naptha on inhalation can cause breathlessness or even coma.
8. Methyl isocyanate. It can affect the respiratory as well as gastro intestinal tract.
Methyl isocyanate poisoning is characterized by serious irritation of eyes etc. it
can prove fatal in high concentrations.
9. Sulphur dioxide. Sulphur dioxide if inhaled causes irritation of throat, nose etc.
and can even cause death in substantially high concentrations.
10. Phosgene. Phosgene if inhaled seriously affects the respiratory system etc. And
can cause death in case of high exposures.
