Industrial hygiene № 28

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INDUSTRIAL HYGIENE INDUSTRIAL HYGIENE The 3 definite elements in The 3 definite elements in industrial hygiene are the industrial hygiene are the recognition, evaluation and control of occupational health hazards. The The recognition of health of health hazards has primacy, since it hazards has primacy, since it must take place before proper must take place before proper evaluation or (if needed) evaluation or (if needed) control can take place. control can take place. Upon recognition of a health hazard,

Transcript of Industrial hygiene № 28

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INDUSTRIAL HYGIENEINDUSTRIAL HYGIENE

The 3 definite elements in industrial hygiene The 3 definite elements in industrial hygiene are the are the recognition, evaluation and control

of occupational health hazards.

The The recognition of health hazards has of health hazards has primacy, since it must take place before proper primacy, since it must take place before proper

evaluation or (if needed) control can take evaluation or (if needed) control can take place. place. Upon recognition of a health hazard, the industrial hygienist should be able to identify measures necessary for proper evaluation.

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Upon completion of the evaluation, the industrial Upon completion of the evaluation, the industrial hygienist then is in a position – in consultation with hygienist then is in a position – in consultation with

other members of the occupational health safety other members of the occupational health safety team – to team – to recommend controls needed to reduce

exposures to tolerable limits.-1).-1). Recognition of health hazards in the Recognition of health hazards in the

workplaceworkplaceThis is the first step in the process leading to This is the first step in the process leading to

evaluation and control and entails the evaluation and control and entails the identification of materials and processes

that have the potential for causing harm to workers.

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Sources of information about health Sources of information about health hazardshazards include clinical data about include clinical data about

health problems in exposed health problems in exposed populations; information in scientific populations; information in scientific journals and reports of government journals and reports of government

agencies; direct agencies; direct reports from workers, union representatives, supervisors, or

employers.

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Inspection of the workplaceInspection of the workplace is the best is the best source of directly relevant data about health source of directly relevant data about health

hazards. hazards. There is no substitute for There is no substitute for observation of

work practices, use of , use of chemical and physical agents, and , and apparent effectiveness

of control measures.The physician should be able to recognize The physician should be able to recognize

major and obvious health hazards and major and obvious health hazards and distinguish those that require formal distinguish those that require formal

evaluation by the industrial hygienist.evaluation by the industrial hygienist.

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The The ““walk through survey”walk through survey” in the in the company of the occupational health company of the occupational health

physician is the physician is the first and most important first and most important technique for recognition of occupational technique for recognition of occupational

health hazardshealth 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.

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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.

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Questions should then be asked Questions should then be asked regarding regarding the handling of unknown materials or materials about which

insufficient information is availableable. . The incoming materials should The incoming materials should

then be followed into the process flow then be followed into the process flow stream, and stream, and each of the process of

interest in the plant should be observed in action. .

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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.

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Observations to be made. Observations to be made. At each point in the process, the At each point in the process, the industrial industrial

hygienist should observe hygienist should observe handling procedures as well as as well as any protective measures that are employed. Use of that are employed. Use of

respiratory protection and and protective clothing should be recorded, as well as other common should be recorded, as well as other common

sense observations such as the sense observations such as the apparent effectiveness of engineering controls – as – as indicated by absence of characteristic

odors, visible dust accumulations, and loud noise. .

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The survey should continue through to the final product produced by the

plant and its packing.

The industrial hygienist should also The industrial hygienist should also follow the pathway of any follow the pathway of any waste

materials and determine their and determine their disposal sites.

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The The number of employees at each step at each step should be noted, as well as any relevant should be noted, as well as any relevant data on data on gender, ethnicity, or age that that might affect employees’ sensitivity to might affect employees’ sensitivity to

chemicals in the workplace. chemicals in the workplace. It is also important It is also important to look for obvious

stigmas such as drying of skin, as might s such as drying of skin, as might expected where exposure to solvents expected where exposure to solvents

occurs.occurs.

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Data review. Data review. Important part of the industrial hygienist’s Important part of the industrial hygienist’s role in recognition of health hazards in the role in recognition of health hazards in the

workplace will be data review. workplace will be data review. Such data may include Such data may include reports from

physicians on clinical findings that may be related to exposures in the workplace lace as well as a review of as well as a review of company records on materials coming into the workplace coming into the workplace

that may present significant hazards. that may present significant hazards.

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A common-sense duty of the employer is A common-sense duty of the employer is to inform workers of the nature and to inform workers of the nature and

hazards of materials to which they may be hazards of materials to which they may be exposedexposed. .

In some cases, the industrial hygienist must In some cases, the industrial hygienist must assess the potential for harm of chemicals for assess the potential for harm of chemicals for which no reliable human toxicological data which no reliable human toxicological data are available. This need arises most often in are available. This need arises most often in research and development settings but also research and development settings but also

wherever wherever chemical intermediates are

produced. .

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An important consideration is that An important consideration is that the worker the worker must be protected at all costmust be protected at all cost. If uncertainty . If uncertainty

exists, it should be resolved in favor of highest exists, it should be resolved in favor of highest standard of concern.standard of concern.

Upon competition of the walk-through survey, Upon competition of the walk-through survey, the industrial hygienist will ordinary have a the industrial hygienist will ordinary have a

closing conferenceclosing conference with the plant management, with the plant management, at at which timewhich time obvious concerns can be obvious concerns can be

discussed and follow-up measures agreed discussed and follow-up measures agreed upon.upon.

. .

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2).Evaluation of health hazards2).Evaluation of health hazards

Evaluation of health hazards within Evaluation of health hazards within the plant will include measurements the plant will include measurements

of exposures, comparison of those of exposures, comparison of those exposures to existing standards, and exposures to existing standards, and

recommendations of controls, if recommendations of controls, if needed.needed.

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Exposure measurementsExposure measurements. .

They are intended to be determinations They are intended to be determinations of of doses delivered to the individual.doses delivered to the individual.

The mere existence of chemicals in the The mere existence of chemicals in the workplace – or even in the workplace workplace – or even in the workplace

atmosphere – does not necessary imply atmosphere – does not necessary imply that the chemicals are being delivered that the chemicals are being delivered

to a sensitive organ system.to a sensitive organ system.

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The The effectiveeffective dose dose will depend upon such will depend upon such things as things as particle sizes particle sizes of dusts in the air, of dusts in the air, the the use of protective devices use of protective devices (respirators, (respirators, protective clothing), and the protective clothing), and the existence of existence of

other other contaminants in the workplace.contaminants in the workplace.The task of determining the dose delivered The task of determining the dose delivered to the worker may be complicated by the to the worker may be complicated by the

existence of existence of multiple pathways of multiple pathways of absorption and metabolismabsorption and metabolism. .

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Such contaminants as Such contaminants as lead are absorbed lead are absorbed readily both through inhalation and readily both through inhalation and

ingestioningestion, and both routes of intake must , and both routes of intake must be considered in evaluation of the potential be considered in evaluation of the potential

for harm. for harm. Similarly, many Similarly, many solvents are readily solvents are readily

absorbed through the skin, and mere absorbed through the skin, and mere determination of airborne levels is not determination of airborne levels is not sufficient to determine the complete sufficient to determine the complete

range of potential exposures. range of potential exposures.

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Inhalation of airborne contaminInhalation of airborne contaminantsants is the is the major route of entry for systemic major route of entry for systemic

intoxicants. intoxicants. Thus, evaluation and control of Thus, evaluation and control of airborne contaminants is an important part airborne contaminants is an important part

of any occupational health programof any occupational health program..Sampling and analysis of airborne Sampling and analysis of airborne

contaminantscontaminants is the definite function of the is the definite function of the industrial hygienist. The methods for industrial hygienist. The methods for

sampling and analysis of airborne sampling and analysis of airborne contaminants have been already discussed.contaminants have been already discussed.

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Evaluation of physical agents Evaluation of physical agents requires specialized equipment that requires specialized equipment that

is often not routinely available is often not routinely available (except for sound level meters). (except for sound level meters).

Evaluation of ionizing or non-Evaluation of ionizing or non-ionizing radiation requires ionizing radiation requires

specialized training.specialized training.

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3).Control of health hazards3).Control of health hazardsUpon completion of evaluation, the industrial Upon completion of evaluation, the industrial

hygienist should hygienist should recommend recommend appropriate appropriate controlscontrols, if needed. , if needed.

Recommendations should 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 Controls should be adequate to adequate to prevent unnecessary exposure prevent unnecessary exposure

during accidents and emergenciesduring accidents and emergencies as well as as well as during normal conditions.during normal conditions.

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Engineering controlsEngineering controlsEngineering controls to toxic Engineering controls to toxic exposures consist mainly of:exposures consist mainly of:

- enclosure - enclosure – – building structures building structures around the sources of emissionsaround the sources of emissions

- isolation - isolation –– placing hazardous process placing hazardous process components in areas with limited components in areas with limited

human contact and human contact and - VENTILATION- VENTILATION

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Local exhaust ventilation Local exhaust ventilation confirms to the confirms to the principle that control should be implemented principle that control should be implemented

as near to the source as practically possibleas near to the source as practically possible. .

Thus, application of a Thus, application of a local exhaust inlet on local exhaust inlet on a specific toola specific tool (such as grinder) would be (such as grinder) would be

more desirable than more desirable than performing the grinding performing the grinding operation in a operation in a ventilated hoodventilated hood, which in turn , which in turn

would would be more desirable thanbe more desirable than installing installing general ventilation general ventilation in the room where the in the room where the

grinding is performed. grinding is performed.

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In a situation where a In a situation where a very toxic substance very toxic substance is being manipulated in such a way that the is being manipulated in such a way that the

exposure is possible, exposure is possible, all 3 ventilation all 3 ventilation systems might be reasonable to usesystems might be reasonable to use..

Thus, Thus, the operator the operator would be protected by would be protected by the ventilation of the specific toolthe ventilation of the specific tool, , nearby nearby workersworkers (as well as the operator) would be (as well as the operator) would be protected protected by the hood by the hood and and the reminder of the reminder of

the building the building would be protected by would be protected by the the general ventilation system.general ventilation system.

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Design of ventilation systems for Design of ventilation systems for contamination control should ordinarily contamination control should ordinarily

not to be left to engineers without not to be left to engineers without specific background or experience. specific background or experience.

Similarly, an industrial hygienist without Similarly, an industrial hygienist without engineering training and experience in engineering training and experience in

the process to be controlled may produce the process to be controlled may produce an unsatisfactory design.an unsatisfactory design.

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SubstitutionSubstitution

All possibilities for substitution of a nontoxic All possibilities for substitution of a nontoxic for a toxic material or agent should be for a toxic material or agent should be

explored. explored. If a toxic material can be dispersed with a If a toxic material can be dispersed with a

less harmful, that should be done. less harmful, that should be done. Substitution can be done, of course, Substitution can be done, of course, if a useful if a useful

substitute is availablesubstitute is available – one that is suitable – one that is suitable for existing processes or for which the process for existing processes or for which the process

can be relatively easily adapted.can be relatively easily adapted.

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Controls on human behaviorControls on human behavior – – these can be subdivided into the these can be subdivided into the

general categories of general categories of administrativeadministrative c c ontrols and ontrols and work practice work practice controls.controls.

- - Administrative controls Administrative controls – – includes includes such things as establishment of such things as establishment of prohibited prohibited areasareas, areas where smoking and eating are , areas where smoking and eating are

either prohibited or allowed, and seither prohibited or allowed, and safe afe pathways through the work environmentpathways through the work environment..

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Administrative controls will also include Administrative controls will also include work schedulingwork scheduling in such a way that in such a way that dangerous operations are carried out dangerous operations are carried out when fewest workers are present.when fewest workers are present.

Less desirable Less desirable is the practice of is the practice of scheduling individual workers to scheduling individual workers to

perform tasks for perform tasks for short periods, where short periods, where excessive exposures would be excessive exposures would be

incurredincurred. .

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This practice was at one time common in This practice was at one time common in nuclear power industrynuclear power industry, where temporary , where temporary employees employees (“jumpers”) (“jumpers”) were employed were employed

and paid by the day, although their actual and paid by the day, although their actual work period may have been as short as 15 work period may have been as short as 15 minutes. Such practices, where exposure minutes. Such practices, where exposure

to carcinogenic or genotoxic agent is to carcinogenic or genotoxic agent is spread across a larger population group spread across a larger population group

although individual exposures are lower, although individual exposures are lower, is is entirely unacceptable. entirely unacceptable.

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- Work practices control - Work practices control – – implies implies control over the behavior of individual control over the behavior of individual

workers on the job.workers on the job.

Such details as handling of contaminated Such details as handling of contaminated tools are included. tools are included.

EducationEducation ( (on the hazards to be avoided) on the hazards to be avoided) and and training training (on the desired practices) (on the desired practices)

are required. are required.

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Controls on work practices are Controls on work practices are particularly important particularly important where where

engineering controls are either not engineering controls are either not adequate or not possibleadequate or not possible and where and where

there is there is significant potential for significant potential for generation of airborne generation of airborne

contaminants outside of controlled contaminants outside of controlled placesplaces..

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Personal protectionPersonal protectionPersonal protective equipment use, Personal protective equipment use,

though often essential, is less desirable though often essential, is less desirable than other approaches because of the than other approaches because of the difficulty in ensuring that it is both difficulty in ensuring that it is both

used and effective. used and effective. Examples on construction sites are Examples on construction sites are

“hard hats” “hard hats” and and “safety shoes”. “safety shoes”.

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In laboratory environments, the use In laboratory environments, the use of protective eyewear is common, of protective eyewear is common,

as is the use of protective garments, as is the use of protective garments, such as laboratory coats.such as laboratory coats.

However, there are significant However, there are significant complexities in both design and complexities in both design and

function of the protective devices function of the protective devices used to reduce exposures. used to reduce exposures.