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  Formalin
(formaldehyde 40% solution) is still the most commonly used fixing agent;
acetone is a widely employed solvent.
Such substances expose the personnel to the following occupational risks:
(i) Fires, outbursts and explosions.
In fact, many compounds (such as organic solvents) are volatile and
easily inflammable; risks deriving from the use of compressed or
liquefied gases (oxygen, nitrogen, carbon dioxide, helium and others)
should be also mentioned.
(ii) Irritations and caustic injuries (chemical burns).
Acids and bases, but also some salts, have a noxious power which varies
in strength with the tissue these substances come in contact with. Some
compounds (for example fluoridric acid, sodium hydroxide) may be
responsible for very bad injuries to the skin, the eyes and, in case of
accidental ingestion, to the upper digestive system. Furthermore,
irritating gases and vapours (such as gaseous chlorine) may develop
during different reactions.
(iii) Acute intoxications.
Extremely powerful poisons, such as cyanide, arsenic, mercury compounds,
animal and vegetal toxins, may be found in the laboratories. Intoxication
may occur as a result of accidental ingestion or inhalation or, less
frequentely, as a result of skin contact or inoculation (for example,
through needles or glassworks' fragments).
(iv) Chronic intoxications.
These may arise as a consequence of prolonged exposure to relatively
small doses, unable to produce acute effects. For example, it has been
widely reported that chronic exposure to organic solvents, as it may
happen in industry workers, may lead to pathological changes in different
organs and apparatuses. The most frequently reported toxic effects
include liver disease, nephropathy, coagulation disorders and nervous
system disorders. However, the amounts of substances generally employed
in laboratories are small if compared to the amounts employed in
industry, and even the exposure time is shorter. On the other hand, the
exposure in a laboratory is usually irregular and is often simultaneous
to a big variety of compounds. Furthermore, the constant potentiation of
the analytical activity involves the introduction of new techniques and
instrumentation that make manipulation and risk conditions very variable.
Therefore, very few attempts of evaluating the chronic toxic risk in a
laboratory exist, making it impossible to draw conclusions. In fact,
there is no significant epidemiological study on the predominant diseases
in such environment and the only accounts in the literature refer to
sporadic clinical cases.
(v) Allergies.
Many substances in the laboratory (such as citric acid, picric acid,
sulphanilic acid, chrome and compounds, formaldehyde, hydrazine,
hydroquinone, nitroaniline, paraffin, piridine, o-tolouidine, triethanolamine)
may induce cutaneous or, rarely, respiratory sensitization. These events
are poorly foreseeable and strongly conditioned by the individual
susceptibility of the exposed subjects.
(vi) Carcinogenesis and
mutagenesis.
Substances
with ascertained mutagenic and/or carcinogenic activity (such as benzene,
bischloromethylether, chrome and compounds) and with suspected mutagenic
and/or carcinogenic activity (such as chloroform, formaldehyde, carbon
tetrachloride) are often found in biomedical laboratories. Their
manipulation is a crucial toxicological problem in the laboratory ambit. This
problem has been studied since the 1970s by means of epidemiological
studies and chromosomic maps, but no univocal result has been obtained on
whether laboratory workers have a significantly higher mutagenic or
carcinogenic risk. In these studies, general mortality data for cancer
are discordant (major evidence being about malignant haematological
disorders and nervous system cancer). The major difficulty consists in
the precise estimate of the exposure because usually it has been
estimated on the basis of the qualification of the subjects and of the
working site. This entails enormous difficulties in identifying the
compounds or the groups of compounds responsible for the reported
malignancies.
For additional information
Databases
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