Industrial Safety and Health for Goods and Materials Services - Chapter 8 docx

If, I have continuously used the term exposure since, unlike traumainjuries and deaths, which are usually caused by the release of some source of energy,occupational illnesses are often

8 Health Hazards

8.1 OCCUPATIONAL ILLNESSES

Occupation illnesses are not as easily identified as injuries According to the Bureau

of Labor Statistics, there were 5.7 million injuries and illnesses reported in 1999 Ofthis number only 372,000 cases of occupational illnesses were reported The 372,000occupational illnesses included repeat trauma such as carpal tunnel syndrome, noise-induced hearing loss, and poisonings It certainly appears that many occupationalillnesses go unreported when the employer or worker is not able to link exposurewith the symptoms the employees are exhibiting Also, physicians fail to ask the rightquestions regarding the patients employment history, which can lead to the com-monest of diagnoses of a cold orflu This has become very apparent with the recentoccupational exposure to anthrax where a physician sent a worker home withanthrax without addressing his=her potential occupational exposure hazards Unless

Exposure in the workplace can cause occupationally related illnesses (Courtesy of the U.S.Environmental Protection Agency.)

physicians are trained in occupational medicine, they seldom address work as thepotential exposure source.

This is not entirely a physician problem by any means since the symptoms that areseen by the physician are often those offlu and other common illnesses suffered by thegeneral public It is often up to the employee to make the physician aware of their on-the-job exposure If, I have continuously used the term exposure since, unlike traumainjuries and deaths, which are usually caused by the release of some source of energy,occupational illnesses are often due to both short- and long-term exposures Ifthe result of an exposure leads to immediate symptoms, it is said to be acute If thesymptoms come at a later time, it is termed a chronic exposure The time betweenexposure and the onset of symptoms is called the latency period It could be days,weeks, months, or even years, as in the case of asbestos where asbestosis or lungcancer appears 20–30 years after exposure

It is often very difficult to get employers, supervisors, and employees to takeseriously the exposures in the workplace as a potential risk to the workforce both shortand long term, especially long term.‘‘It cannot be too bad if I feel alright now.’’ Thisfalse sense of security is that the workplace seems safe enough The question is howbad could it be in our workplace? Everyone seems well enough now

8.2 IDENTIFYING HEALTH HAZARDS

Health-related hazards must be identified (recognized), evaluated, and controlled toprevent occupational illnesses, which come from exposure to them Health-relatedhazards come in a variety of forms, such as chemical, physical, ergonomic, orbiological:

. Chemical hazards arise from excessive airborne concentrations of mists,

vapors, gases, or solids that are in the form of dusts or fumes In addition

to the hazard of inhalation, many of these materials may act as skin irritants ormay be toxic by absorption through the skin Chemicals can also be ingestedalthough this is not usually the principle route of entry into the body

. Physical hazards include excessive levels of nonionizing and ionizing

radiations, noise, vibration, and extremes of temperature and pressure

. Ergonomic hazards include improperly designed tools or work areas.

Improper lifting or reaching, poor visual conditions, or repeated motions

in an awkward position can result in accidents or illnesses in the tional environment Designing the tools and the job to be done to fitthe worker should be of prime importance Intelligent application of engin-eering and biomechanical principles is required to eliminate hazards ofthis kind

occupa-. Biological hazards include insects, molds, fungi, viruses, vermin

(birds, rats, mice, etc.), and bacterial contaminants (sanitation and keeping items such as potable water, removal of industrial waste andsewage, food handling, and personal cleanliness can contribute to theeffects from biological hazards) Biological and chemical hazards canoverlap

house-Health-rela ted hazards can often be elusive and difficult to identify A commonexample of this is a contamina nt in a building that has caused symptom s of illness Even the ev aluation process may not be able to detect the contam inant that hasdissipated before a samp le can be coll ected This leaves nothi ng to contr ol andpossibly no an swer to what caused the ill nesses Table 8.1 depicts the most commonreported illness es in the wor kplace.

8.3 HEALTH HAZARDS

Health hazards are caused by any chemi cal or biol ogical exposur e that inte ractsadversely with organs wi thin our body causi ng illn esses or injuries The maj ority ofchemical expo sures result from inhal ing chemi cal contam inants in the form ofvapors, gases, dusts , fume s, and mis ts, or by skin ab sorption of these mat erials.The degree of the hazard depends on the lengt h of exposur e time and the amoun t orquantity of the chemi cal agen t This is co nsidered to be the dose of a substanc e Achemical is consi dered a poiso n when it causes harmful effects or inte rferes withbiological react ions in the body Only those chemi cals that are associated wi th agreat risk of harmful effects are desig nated a s poiso ns (Figur e 8.1)

Dose is the most importan t factor deter mining whether or not you will have anadverse effect from a chemi cal exposur e The longer you wor k at a job and the morechemical agent that gets into the air or on you r skin, the higher the dose potent ial.Two compo nents that make up dose are as follow s:

1 The length of exposur e, or how long you are exposed — 1 h, 1 day, 1 year,

TABLE 8.1

Repor ted Non fatal Occupat ional Illnesses

Type of Illness

Total Illnesses Reported (%) Skin disease or disorders 17

Respiratory conditions because of toxic agents 8

Poisoning 1

Hearing loss 11

All other diseases 62

Source: From Bureau of Labor Statistics United States Department

of Labor Workplace Injuries and Illnesses in 2004.

Available at http: ==bls.gov

synergistic effect Many chemicals can interact and although the dose of any onechemical may be too low to affect you, the combination of doses from differentchemicals may be harmful For example, the combination of chemical exposures and

a personal habit such as cigarette smoking may be more harmful than just anexposure to one chemical Smoking and exposure to asbestos increase the chance

of lung cancer by as much as 50 times

The type and severity of the body’s response is related to dose and the nature ofspecific contaminant present Air that looks dirty or has an offensive odor may, infact, pose no threat whatsoever to the tissues of the respiratory system In contrast,some gases that are odorless or at least not offensive can cause severe tissue damage.Particles that normally cause lung damage cannot even be seen Many times,however, large visible clouds of dust are a good indicator that smaller particlesmay also be present

The body is a complicated collection of cells, tissues, and organs havingspecial ways of protecting itself against harm We call these the body’s defensesystems The body’s defense system can be broken down, overcome, or bypassed.This can result in injury or illness Sometimes, job-related injuries or illnessesare temporary, and you can recover completely At other times, as in the case ofchronic lung diseases like silicosis or cancer, these are permanent changes that maylead to death

FIGURE 8.1 Chemical exposure poses real health issues for workers (Courtesy of the U.S.Environmental Protection Agency.)

8.3.1 ACUTEHEALTHEFFECTS

Chemicals can cause acute (short-term) or chronic (long-term) effects Whether ornot a chemical causes an acute or chronic reaction depends both on the chemical andthe dose you are exposed to Acute effects are seen quickly, usually after exposures

to high concentrations of a hazardous material For example, the dry cleaning solventperchloroethylene can immediately cause dizziness, nausea, and at higher levels,coma and death Most acute effects are temporary and reverse shortly after beingremoved from the exposure But at high enough exposures permanent damage mayoccur For most substances, neither the presence nor absence of acute effects can beused to predict whether chronic effects will occur Dose is the determining factor.Exposures to cancer-causing substances (carcinogens) and sensitizers may lead toboth acute and chronic effects

An acute exposure may occur, for example, when we are exposed to ammoniawhile using another cleaning agent Acute exposure may have both immediate anddelayed effects on the body Nitrogen dioxide poisoning can be followed by signs ofbrain impairment (such as confusion, lack of coordination, and behavioral changes),days or weeks after recovery

Chemicals can cause acute effects on breathing Some chemicals irritate the lungsand some sensitize the lungs Fluorides, sulfides, and chlorides are all found in variouswelding and solderingfluxes During welding and soldering, these materials combinewith the moisture in the air to form hydrofluoric, sulfuric, and hydrochloric acids Allthree can severely burn the skin, eyes, and respiratory tract High levels can overwhelmthe lungs, burning and blistering them, and causing pulmonary edema (Fluid building

up in the lungs will cause shortness of breath and if severe enough can cause death.)

In addition, chemicals can have acute effects on the brain When inhaled, solventvapors enter the bloodstream and travel to other parts of the body, particularly thenervous system Most solvents have a narcotic effect This means they affectthe nervous system by causing dizziness, headaches, inebriation, and tiredness.One result of these symptoms may be poor coordination, which can contribute tofalls and other accidents on a worksite Exposure to some solvents may increase theeffects of alcoholic beverages

8.3.2 CHRONICHEALTHEFFECTS

A chronic exposure occurs during longer and=or repeated periods of contact, times over years and often at relatively low concentrations of exposure Perchloro-ethylene or alcohol, for example, may cause liver damage or other cancers 10–40years afterfirst exposure This period between first exposure and the development ofthe disease is called the latency period An exposure to a substance may causeadverse health effects many years from now with little or no effects at the time ofexposure It is important to avoid or eliminate all exposures to chemicals that are notpart of normal ambient breathing air For many chemical agents, the toxic effectsfollowing a single exposure are quite different from those produced by repeatedexposures For example, the primary acute toxic effect of benzene is central nervoussystem damage, while chronic exposures can result in leukemia

some-There are two ways to determine if a chemical causes cancer: studies conducted onpeople and studies on animals Studies on humans are expensive, difficult, and nearimpossible This type of long-term research is called epidemiology Studies onanimals are less expensive and easier to carry out This type of research is sometimesreferred to as toxicology Results showing increased occurrences of cancer in animalsare generally accepted to indicate that the same chemical causes cancer in humans Thealternative to not accepting animal studies means we would have a lot less knowledgeabout the health effects of chemicals We would never be able to determine the healtheffects of the more than 100,000 chemicals used by the industry.

There is no level of exposure to cancer-causing chemicals that is safe Lowerlevels are considered safer One procedure for setting health standard limits is calledrisk assessment Risk assessment on the surface appears very scientific yet the actualresults are based on many assumptions It is differences in these assumptions thatallow scientists to come up with very different results when determining an acceptableexposure standard The following are major questions that assumptions are based on:

. Is there a level of exposure below which a substance would not cause

cancer or other chronic diseases? (Is there a threshold level?)

. Can the body’s defense mechanisms inactivate or break down chemicals?

. Does the chemical need to be at a high enough level to cause damage to a

body organ before it will cause cancer?

. How much cancer should we allow? (One case of cancer among 1 million

people, or one case of cancer among 100,000 people, or one case of canceramong 10 people?)

For exposures at the current permissible exposure limit (PEL), the risk of loping cancer from vinyl chloride is about 700 cases of cancer for each million workersexposed The risk for asbestos is about 6,400 cases of cancer for each millionworkers exposed The risk for coal tar pitch is about 13,000 cases for eachmillion workers exposed PELs set for current federal standards differ because ofthese different risks

deve-The dose of a chemical-causing cancer in human or animal studies is then used toset a standard PEL below which only a certain number of people will develop illness

or cancer This standard is not an absolute safe level of exposure to cancer-causingagents, so exposure should always be minimized even when levels of exposure arebelow the standard Just as the asbestos standard has been lowered in the past from

5 to 0.2fibers=cm3, and now to 0.1fibers=cm3(50 times lower) It is possible thatother standards will be lowered in the future as new technology for analysis isdiscovered and public outrage insists on fewer deaths for a particular type ofexposure If a chemical is suspected of causing cancer, it is best to minimizeexposure, even if the exposure is below accepted levels

8.3.3 CHRONIC DISEASE

Chronic disease is not always cancer There are many other types of chronic diseases,which can be as serious as cancer These chronic diseases affect the function of

different organs of the body For example, chronic exposure to asbestos or silica dust(fine sand) causes scarring of the lung Exposure to gases such as nitrogen oxides orozone may lead to destruction of parts of the lung No matter what the cause, chronicdisease of the lungs will make the individual feel short of breath and limit theiractivity Depending on the extent of disease, chronic lung disease can kill In fact, it

is one of the top 10 causes of death in the United States

Scarring of the liver (cirrhosis) is another example of chronic disease It is alsoone of the 10 causes of death in the United States The liver is important in makingcertain essential substances in the body and cleaning certain waste products Chronicliver disease can cause fatigue, wasting away of muscles, and swelling of stomachfromfluid accumulation Many chemicals such as carbon tetrachloride, chloroform,and alcohol can cause cirrhosis of the liver

The brain is also affected by chronic exposure Chemicals such as lead candecrease IQ and memory, and=or increase irritability Many times these changes aresmall and can only be found with special medical tests Workers exposed to solvents,such as toluene or xylene in oil-based paints, may develop neurological changes over

a period of time

Scarring of the kidney is another example of a chronic disease Individuals withsevere scarring must be placed on dialysis to remove the harmful waste products orhave a kidney transplant Chronic kidney disease can cause fatigue, high bloodpressure and swollen feet, as well as many other symptoms Lead, mercury, andsolvents are suspect causes of chronic kidney disease

8.3.4 BIRTHDEFECTS=INFERTILITY

The ability to have a healthy child can be affected by chemicals in many differentways A woman may be unable to conceive because a man is infertile The production

of sperm may be abnormal, reduced, or stopped by chemicals that enter the body.Men working in an insecticide plant manufacturing 1,3-dibromo-3-chloropropane(DBCP) realized after talking among themselves that none of their wives hadbeen able to become pregnant When tested, all the men were found to be sterile

A woman may be unable to conceive or may have frequent early miscarriagesbecause of mutagenic or embryotoxic effects Changes in genes in the woman’sovaries or man’s sperm from exposure to chemicals may cause the developingembryo to die A woman may give birth to a child with a birth defect because of achemical with mutagenic or teratogenic effects When a chemical causes a terato-genic effect, the damage is caused by the woman’s direct exposure to the chemical.When a chemical causes a mutagenic effect, changes in genes from either the man orwoman have occurred

Many chemicals used in the workplace can damage the body Effects range fromskin irritation and dermatitis to chronic lung diseases such as silicosis and asbestosis

or even cancer The body may be harmed at the point where a chemical touches orenters it This is called a local effect When the solvent benzene touches the skin, itcan cause drying and irritation (local effect)

A systemic effect develops at some place other than the point of contact.Benzene can be absorbed through the skin, breathed into the lungs, or ingested

Once in the body, benzene can affect the bone marrow, leading to anemia andleukemia (Leukemia is a kind of cancer affecting the bone marrow and blood.)Adverse health effects may take years to develop from a small exposure or mayoccur very quickly to large concentrations.

8.4 BIOLOGICAL MONITORING

Biological monitoring is the analysis of body systems such as blood, urine,nails, teeth, etc that provide a baseline level of contaminants in the body Medicaltesting can have several different purposes, depending on why the worker is visiting

finger-a doctor If it is finger-a preemployment exfinger-aminfinger-ation, it is usufinger-ally considered finger-a bfinger-aseline touse as a reference for future medical testing Baselines are a valuable tool to measurethe amount of toxic substances in the body and often give an indication of theeffectiveness of personal protective equipment (PPE) (Figure 8.2)

Occupational Safety and Health Administration (OSHA) regulations allow theexamining physician to determine most of the content reviewed in the examination.Benefits received from an examination will vary with content of the examination Nomatter what tests are included in the examination, there are certain importantlimitations of medical testing:

. Medical testing cannot prevent cancer Cancer from exposure to chemicals

or asbestos can only be prevented by reducing or eliminating an exposure

. For many conditions, there are no medical tests for early diagnosis For

example, the routine blood tests conducted by doctors for kidney functions

do not become abnormal until half the kidney function is lost Nine of ten

FIGURE 8.2 Biological monitoring is a part of medical assessment (Courtesy of the U.S.Environmental Protection Agency.)

people with lung cancer die withi n 5 years because chest x-rays do no tdiagnose lung cancer in time to save the indi vidual.

. No medical test is perfect So me tests are falsely abnormal and some false ly

normal

8.4.1 MEDICAL QUESTIONNAIRE

A medical and work history, despi te comm on percept ions, is probably the mostimportan t part of an examinati on Most diagno ses of disea se in medi cine are made bythe work history Labo ratory tests are used to con firm past illness es and inju ries.Doctors are inte rested in the history of lung, heart , kidney , liver, and other chroni cdiseases for the indi vidual and family The doctor will also be concern ed aboutsymptom s indi cating heart or lung disea se and smok ing habits

A physic al examinati on is very bene ficial for routi ne screen ing Good results areimportan t but an indi vidual may be physi cally fit and still have a serious medicalproblem Blood is test ed for blood cell production (anemia), liver function, kidneyfunction, and if taken while fast ing, for increased sugar, choles terol, an d fat in theblood Urine is tested for kidney funct ion and diabet es (sugar in the urine) It ispossible to meas ure in the blood and urine c hemicals that get into the body fromexposures on a jobsite This type of testing is call ed biol ogical monitor ing

8.4.2 P ULMONARY FUNCTION T ESTS

A spiro meter measures the volume of air in an indi vidual ’ s lungs and how quickly

he=she can breathe in and out This is called pulmonary funct ion testing This isuseful for diagnosing disea ses that cause scarr ing of the lungs that affect s theexpandab ility (asbes tosis) Emphys ema or asthma may also be diagno sed withpulmonary funct ion testing It is vital for ev aluating the abil ity of an individua l towear a respirato r without additional healt h risk

8.4.4 CHESTX-RAY

X-rays are useful in determining the cause of breathing problems or to use as abaseline to determine future problems A chest x-ray is used to screen for scarring ofthe lungs from exposure to asbestos or silica It should not be performed routinely,unless the history indicates a potential lung or heart problem and the physician thinks

a chest x-ray is necessary Some OSHA regulations require chest x-rays as part of themedical surveillance program Unnecessary x-ray screening should be eliminated.For work-related biological monitoring, it is sufficient to have chest x-rays every

5 years

8.5 HAZARDOUS CHEMICALS

Hazardous and toxic (poisonous) substances can be defined as harmful chemicalspresent in the workplace In this definition, the term ‘‘chemicals’’ includes dusts,mixtures, and common materials such as paints, fuels, and solvents OSHA currentlyregulates exposure to approximately 400 substances The OSHA chemical samplinginformationfile contains a listing for approximately 1500 substances The Environ-mental Protection Agency’s (EPA) Toxic Substance Chemical Act Chemical Sub-stances Inventory lists information on more than 62,000 chemicals or chemicalsubstances Some libraries maintain files of material safety data sheets (MSDSs)for more than 100,000 substances It is not possible to address the hazards associatedwith each of these chemicals

Since there is no evaluation instrument that can identify the chemical or theamount of chemical contaminant present, it is not possible to be able to make a real-time assessment of a worker’s exposure to potentially hazardous chemicals Addi-tionally, threshold limit values (TLVs) provided by the American Conference ofGovernmental Industrial Hygienist (ACGIH) in 1968 are the basis of OSHA’s PELs

In the early 2000s, workers are being provided protection with chemical exposurestandards that are 40 years old The ACGIH regularly updates and changes its TLVsbased upon new scientific information and research

The U.S EPA allows for one death or one cancer case per million peopleexposed to a hazardous chemical Certainly, the public needs these kinds of protec-tions Using the existing OSHA PELs, risk factor is only as protective as one deathbecause of exposure in 1000 workers This indicates that there exists a fence linementality which suggests that workers can tolerate higher exposures than what thepublic would be subjected to As one illustration of this, the exposure to sulfur

FIGURE 8.3 Work is often a strain on the heart (Courtesy of the U.S EnvironmentalProtection Agency.)

dioxide for the public is set by the EPA at 0.14 ppm average over 24 h, while theOSHA PEL is 5 ppm average over 8 h Certainly, there is a wide margin betweenwhat the public can be subjected to and what a worker is supposed to be able totolerate The question is,‘‘Is there a difference between humans in the public arenaand those in the work arena?’’ Maybe workers are assumed to be more immune to theeffects of chemicals when they are in the workplace than when they are at home,because of workplace regulations and precautions.

A more significant issue is that regarding mixtures The information does notexist to show the risk of illnesses, long-term illnesses, or the toxicity of combiningthese hazardous chemicals At present, it is assumed that the most dangerouschemical of the mixture has the most potential to cause serious health-relatedproblems, then the next most hazardous, and so on However, little consideration

is given regarding the increase in toxicity, long-term health problems, or presenthazards Since most chemicals used in industry are mixtures formulated by manu-facturers, it makes it even more critical to have access to the MSDSs and take aconservative approach to the potential for exposure This means that any signs orsymptoms of exposure should be addressed immediately, worker complaints should

be addressed with sincerity and true concern, and employers should take precautionsbeyond those called for by the MSDSs if questions persist

Actually, the amount of information that exists on dose=response for chemicalsand chemical mixtures is limited This is especially true for long-range effects If achemical kills or makes a person sick within minutes or hours, the dose response iseasily understood But, if chemical exposure over a long period results in an indivi-dual’s death or illness, then the dose needed to do this is, at best, a guess It mostcertainly does not take into account other chemicals the worker was exposed to duringhis=her work life and whether they exacerbated the effects or played no role in theindividual’s death or illness This is why it is critical for individual workers to keeptheir exposure to chemicals as low as possible Even then, there are no guarantees thatthey may not come down with an occupational disease related to chemical exposure.Many employers and workers as well as physicians are not quick or trained toidentify the symptoms of occupational exposure to chemicals In one case, two menpainted for 8 h with a paint containing 2-nitropropane in an enclosed environment

At the end of their shift, one of the workers felt unwell and stopped at the emergencycenter at the hospital After examination, he was told to take rest and was assured hewould be better the next morning Later that evening, he returned to the hospital anddied of liver failure from 2-nitropropane exposure The other worker sufferedirreparable liver damage but survived No one asked the right questions regardingoccupational exposure The symptoms were probably similar to a common cold or

flu which is often the case unless some investigation is done Often those who sufferfrom chemical poisoning go home and start excreting the contaminant during the

16 h where they have no exposure They feel better the next day and return to workand are reexposed Thus, the worker does not truly recognize this as a poisoningprocess Being aware of the chemicals used, reviewing the MSDSs, and following therecommended precautions are important to the safe use of hazardous chemicals.With this point made, it becomes critical that employers should be aware of thedangers posed to their workforce by the chemicals that they use Employers need to