1. INDUSTRIAL HYGIENE
The 3 definite elements in industrial hygiene
are the recognition, evaluation and control
of occupational health hazards.
The recognition of health hazards has
primacy, since it must take place before proper
evaluation or (if needed) control can take
place. Upon recognition of a health hazard, the
industrial hygienist should be able to identify
measures necessary for proper evaluation.
2. Upon completion of the evaluation, the industrial
hygienist then is in a position – in consultation with
other members of the occupational health safety
team – to recommend controls needed to reduce
exposures to tolerable limits.
-1). Recognition of health hazards in the
workplace
This is the first step in the process leading to
evaluation and control and entails the
identification of materials and processes
that have the potential for causing harm to
workers.
3. Sources of information about health
hazards include clinical data about
health problems in exposed
populations; information in scientific
journals and reports of government
agencies; direct reports from workers,
union representatives, supervisors, or
employers.
4. Inspection of the workplace is the best
source of directly relevant data about health
hazards.
There is no substitute for observation of
work practices, use of chemical and
physical agents, and apparent effectiveness
of control measures.
The physician should be able to recognize
major and obvious health hazards and
distinguish those that require formal
evaluation by the industrial hygienist.
5. The “walk through survey” in the
company of the occupational health
physician is the first and most important
technique for recognition of occupational
health hazards.
The survey should begin with a proper
introduction to plant management and
discussion of the purpose of the survey and
inquiry about any relevant recent
complains.
6. Following the process flow through the
plant is most productive.
The survey might thus begin at the
loading dock, where materials
entering the plant can be examined.
Warning labels, descriptive language
about the chemical composition of
materials, and the packing of the
incoming materials should be noted.
7. Questions should then be asked
regarding the handling of unknown
materials or materials about which
insufficient information is available.
The incoming materials should
then be followed into the process flow
stream, and each of the process of
interest in the plant should be
observed in action.
8. Of interest throughout the survey
will be the methods used for
material handling, particularly at
the places where they are
transferred from manufacturers’
containers into vessels for use
within the plant.
9. Observations to be made.
At each point in the process, the industrial
hygienist should observe handling
procedures as well as any protective
measures that are employed. Use of
respiratory protection and protective clothing
should be recorded, as well as other common
sense observations such as the apparent
effectiveness of engineering controls – as
indicated by absence of characteristic
odors, visible dust accumulations, and loud
noise.
10. The survey should continue through
to the final product produced by the
plant and its packing.
The industrial hygienist should also
follow the pathway of any waste
materials and determine their disposal
sites.
11. The number of employees at each step
should be noted, as well as any relevant
data on gender, ethnicity, or age that
might affect employees’ sensitivity to
chemicals in the workplace.
It is also important to look for obvious
stigmas such as drying of skin, as might
expected where exposure to solvents
occurs.
12. Data review.
Important part of the industrial hygienist’s
role in recognition of health hazards in the
workplace will be data review.
Such data may include reports from
physicians on clinical findings that may
be related to exposures in the workplace
as well as a review of company records
on materials coming into the workplace
that may present significant hazards.
13. A common-sense duty of the employer is
to inform workers of the nature and
hazards of materials to which they may be
exposed.
In some cases, the industrial hygienist must
assess the potential for harm of chemicals for
which no reliable human toxicological data
are available. This need arises most often in
research and development settings but also
wherever chemical intermediates are
produced.
14. An important consideration is that the worker
must be protected at all cost. If uncertainty
exists, it should be resolved in favor of highest
standard of concern.
Upon competition of the walk-through survey,
the industrial hygienist will ordinary have a
closing conference with the plant management,
at which time obvious concerns can be
discussed and follow-up measures agreed
upon.
15. 2).Evaluation of health hazards
Evaluation of health hazards within
the plant will include measurements
of exposures, comparison of those
exposures to existing standards, and
recommendations of controls, if
needed.
16. Exposure measurements.
They are intended to be determinations
of doses delivered to the individual.
The mere existence of chemicals in the
workplace – or even in the workplace
atmosphere – does not necessary imply
that the chemicals are being delivered
to a sensitive organ system.
17. The effective dose will depend upon such
things as particle sizes of dusts in the air,
the use of protective devices (respirators,
protective clothing), and the existence of
other contaminants in the workplace.
The task of determining the dose delivered
to the worker may be complicated by the
existence of multiple pathways of
absorption and metabolism.
18. Such contaminants as lead are absorbed
readily both through inhalation and
ingestion, and both routes of intake must
be considered in evaluation of the potential
for harm.
Similarly, many solvents are readily
absorbed through the skin, and mere
determination of airborne levels is not
sufficient to determine the complete
range of potential exposures.
19. Inhalation of airborne contaminants is the
major route of entry for systemic
intoxicants. Thus, evaluation and control of
airborne contaminants is an important part
of any occupational health program.
Sampling and analysis of airborne
contaminants is the definite function of the
industrial hygienist. The methods for
sampling and analysis of airborne
contaminants have been already discussed.
20. Evaluation of physical agents
requires specialized equipment that
is often not routinely available
(except for sound level meters).
Evaluation of ionizing or non-
ionizing radiation requires
specialized training.
21. 3).Control of health hazards
Upon completion of evaluation, the industrial
hygienist should recommend appropriate
controls, if needed.
Recommendations should take into account
not only the conditions found during the
survey but also those that may be expected
to prevail in the future. Controls should be
adequate to prevent unnecessary exposure
during accidents and emergencies as well as
during normal conditions.
22. Engineering controls
Engineering controls to toxic
exposures consist mainly of:
- enclosure – building structures
around the sources of emissions
- isolation – placing hazardous process
components in areas with limited
human contact and
- VENTILATION
23. Local exhaust ventilation confirms to the
principle that control should be implemented
as near to the source as practically possible.
Thus, application of a local exhaust inlet on
a specific tool (such as grinder) would be
more desirable than performing the grinding
operation in a ventilated hood, which in turn
would be more desirable than installing
general ventilation in the room where the
grinding is performed.
24. In a situation where a very toxic substance
is being manipulated in such a way that the
exposure is possible, all 3 ventilation
systems might be reasonable to use.
Thus, the operator would be protected by
the ventilation of the specific tool, nearby
workers (as well as the operator) would be
protected by the hood and the reminder of
the building would be protected by the
general ventilation system.
25. Design of ventilation systems for
contamination control should ordinarily
not to be left to engineers without
specific background or experience.
Similarly, an industrial hygienist without
engineering training and experience in
the process to be controlled may produce
an unsatisfactory design.
26. Substitution
All possibilities for substitution of a nontoxic
for a toxic material or agent should be
explored.
If a toxic material can be dispersed with a
less harmful, that should be done.
Substitution can be done, of course, if a useful
substitute is available – one that is suitable
for existing processes or for which the process
can be relatively easily adapted.
27. Controls on human behavior –
these can be subdivided into the
general categories of administrative c
ontrols and work practice controls.
- Administrative controls – includes
such things as establishment of prohibited
areas, areas where smoking and eating are
either prohibited or allowed, and safe
pathways through the work environment.
28. Administrative controls will also include
work scheduling in such a way that
dangerous operations are carried out
when fewest workers are present.
Less desirable is the practice of
scheduling individual workers to
perform tasks for short periods, where
excessive exposures would be
incurred.
29. This practice was at one time common in
nuclear power industry, where temporary
employees (“jumpers”) were employed
and paid by the day, although their actual
work period may have been as short as 15
minutes. Such practices, where exposure
to carcinogenic or genotoxic agent is
spread across a larger population group
although individual exposures are lower,
is entirely unacceptable.
30. - Work practices control – implies
control over the behavior of individual
workers on the job.
Such details as handling of contaminated
tools are included.
Education (on the hazards to be avoided)
and training (on the desired practices)
are required.
31. Controls on work practices are
particularly important where
engineering controls are either not
adequate or not possible and where
there is significant potential for
generation of airborne
contaminants outside of controlled
places.
32. Personal protection
Personal protective equipment use,
though often essential, is less desirable
than other approaches because of the
difficulty in ensuring that it is both
used and effective.
Examples on construction sites are
“hard hats” and “safety shoes”.
33. In laboratory environments, the use
of protective eyewear is common,
as is the use of protective garments,
such as laboratory coats.
However, there are significant
complexities in both design and
function of the protective devices
used to reduce exposures.
