Safety In The Prosthetics Workplace

Abstract

"The Occupational Safety and Health Administration (OSHA) has estimated that more than 32 million workers are exposed to 650,000 hazardous chemical products in more than 3 million American workplaces. These can include chemical agents, physical agents and biologic agents." ¹⁰

Introduction

In the prosthetic fabrication process, a number of occupational hazards exist. These include chemical contaminants, airborne contaminants, and noise pollution. Very little information is available on the safety hazards of working in the prosthetics field. The purpose of this research project was to identify safety measures that are used by registered prosthetic technicians across the United States as well as identify any trends in health issues related to safety measure use among these technicians. In addition to this, recommendations for improving safety will be made.

Methods

A survey was sent to 200 registered prosthetic technicians across the United States. All names were randomly selected from the 2000 Registry and Reference Guide from the American Board for Certification in Orthotics and Prosthetics. The survey can be found in Appendix A.

In order to obtain some information on demographics, age, gender, and number of years in the field were requested at the beginning of the survey.

The survey contained four sections to gather data on the availability and use of safety equipment, the use of various chemicals, and the frequency of chronic health issues related to chemical exposure. The first section evaluated the use and availability of safety equipment. The equipment surveyed was latex and vinyl safety gloves, dust masks, respirator or ventilator, eye protection, hearing protection, protective clothing, and ventilation systems. This section also included questions on the availability of MSDS sheets, a dedicated area for lamination, eye wash stations, and safety showers. The final question indicated the respondent's satisfaction with his ventilation system at his current place of employment.,/p>

The second section evaluated the frequency of use of thirteen common products used in the prosthetics fabrication process. The products listed were polyester resin, acrylic resin, epoxy resin, acrylic carbon resin, sealing resin, pedilan foam, solka floc, micro balloon, naugatuck promoter, acetone, ambroid, thermoplastics, and contact cement.

The third section evaluated the use of safety equipment while performing thirteen common tasks. The tasks were laminating, sanding acrylic lamination, sanding polyester lamination, sanding laminated carbon fiber, sanding plastics, sanding polyethylene foam, using naugatuck promoter, using pedilan foam, sanding pedilan foam, using acetone, using ambroid, using contact cement, and using sealing resin with micro balloon or solka floc.

The fourth section focused on any chronic health issues that the respondent may have. Twenty-one common health issues were listed with space for the respondent to list any other issues. The health issues were nausea, vomiting, headaches, dizziness, shortness of breath, asthma, bronchitis, high blood pressure, skin rash, eczema, allergies, hearing loss, heart disease, liver disease, hepatitis, cancer, reduced libido, infertility, low birth weight child, child with birth defects, and child with cancer.

Results

Demographics

Ninety-seven of the 200 surveys were returned. There were ninety male and six female respondents (one respondent left this question blank). The average age of the respondents was 40 with the average number of years in the field being 13.8.

Safety Measures

Table 1 shows the use of protective safety equipment.

The technicians surveyed realize the importance in having their hands protected. Only one person out of 97 never wears safety gloves, 62.9% wear latex gloves daily, 26.8% wear vinyl gloves daily, and 12.4% wear both latex and vinyl safety gloves on a daily basis. Unfortunately, chemical resistant gloves were not included on the survey.

Employers and employees are aware of the importance of a ventilation system and protecting the workers from airborne contaminants. Only 4.1% of the facilities do not have a ventilation system. A dust mask is worn on a daily basis by 50.5% of respondents, 20.6% use a ventilator or respirator on a daily basis, and 89.7% use some sort of a ventilation or vacuum system daily. Only five respondents never use a dust mask or respirator/ventilator; however, all five use a ventilation system on a daily basis.

Eye protection is valued by most of the respondents. Over 80% wear eye protection daily while only 6.2% never wear eye protection.

Unfortunately, hearing protection is not a priority among the respondents. Hearing protection is worn daily by only 21.6% while 50.5% never wear any hearing protection. Over 17% of facilities do not have hearing protection available.

Approximately 70% of respondents have a safety policy in place that is reviewed annually. Over 90% have a dedicated area for lamination and have MSDS sheets available. Almost 75% have an eye wash station but only 15.5% have a safety shower at their facility. See Table 2.

In general, respondents were content with the ventilation systems in their facilities: 34% responded very satisfied, 40.2% somewhat satisfied, 15.5% somewhat dissatisfied, and 12.4% very dissatisfied. Two respondents marked two answers due to their satisfaction in one area of their facility and their dissatisfaction in another area. Many expressed their dissatisfaction with the carbon dust that is perpetually covering everything in their facilities.

Table 3 gives an idea of the frequency of use of various products in the prosthetics field. Special notice should be given to percentages of respondents that use each product on a daily basis. In the discussion section, time will be given to hazards of various chemicals and safety measures that should be practiced when using that specific chemical. Of special concern is the use of acetone in the field due to its high usage and the hazards it may present. Over 75% of respondents use acetone on a daily basis, however, as shown in Table 4, only 39.1% use safety gloves and only 10.9% use a respirator while using acetone. Low use of safety equipment can also be observed among the 84.5% using contact cement on a daily basis with only 20% using safety gloves and 13.7% using a respirator. Encouraging numbers are the low use of polyester resin, Naugatuck Promoter and Ambroid. These three products are a safety concern due to their potential hazards. Over 60% of respondents never or seldom use polyester resin, Naugatuck Promoter, or ambroid. Notice though in table 4 the low use of safety gloves while laminating or using ambroid.

HEALTH ISSUES

Table 5 summarizes the percentage of chronic health issues experienced by the respondents of this survey. Of special concern are headaches at 15.5%, skin rash at 12.4%, allergies at 21.6% and hearing loss at 12.4%. These results are higher than U.S. annual averages as documented by the National Center for Health Statistics.⁹

a     Percentages are calculated based upon rates per 1,000 as found in Prevalence of Chronic Conditions: United States, 1990-1992. 9 The first number represents 18-44 age group; the second number represents 45-64 age group. b     Includes migraine headaches. c     Dermatitis only. d     Excludes deafness. e     Other includes: Psoriasis, anxiety disorder, sinus infection, Epstein Barr Virus, gout, kidney stones, hair loss, development of latex intolerance, and loss of sense of smell.

Discussion

Material safety data sheets (MSDS) contain information on the chemical and physical properties of a product, potential health hazards, emergency and first aid, storage and handling, personal protection, and environmental and regulatory data. As an employee using the chemical product, it is important to understand the health hazards involved in using the product and the safety measures that should be used to prevent potential health hazards.

The U.S. Government's Occupational Safety and Health Administration (OSHA) requires MSDS sheets to be available for all products that pose a hazard in the workplace. This is documented in Hazard Communications Standard 29 CFR 1910.1200. All manufacturers of hazardous chemicals or products are required to supply material safety data sheets to all purchasers of their products. They are required to distribute this information upon the first purchase of a product, when there is a change in the chemical's composition, or when new significant information is available on the product. A product is termed "hazardous" if acute or chronic health effects may occur in exposed employees. OSHA requires that all employees have ready access to MSDS information when they are in their work area and that all employees are adequately trained in the hazards of all of the chemicals that they use.¹⁸

For the purpose of this research project, twenty-seven different MSDS sheets were reviewed for thirteen various products used in the prosthetic fabrication process. A list of these products and the manufacturers can be found in Appendix B. This is only a small sampling of the various products that are available in the prosthetics field. Upon reviewing the MSDS sheets, information was broken down based upon:

• Potential health effects

• Exposure limits

• Exposure control and personal protection

POTENTIAL HEALTH EFFECTS

Appendix C lists products and their potential health effects as found from the reviewed MSDS. The health effects are divided by eye, skin, inhalation, and ingestion. It is also noted if the product contains a known carcinogen or has been found to cause birth defects. The final column lists the target organs that may be affected by the product if exposure occurs. Almost all of the products studied were found to be an irritant to the eyes, skin, and respiratory system. The thinners (acetone and solvents) and adhesives were found to cause defatting of the skin and possible central nervous system depression.

Of special concern:

• Unsaturated polyester resin: can cause lung injury when inhaled or ingested; possible carcinogen; has caused birth defects in laboratory animals; can affect the auditory system

• Epoxy Vinyl Ester Resin: possible carcinogen; can affect the auditory system

• Hardener for Pedilan Foam: can cause possible corneal damage

• Naugatuck Promoter (Diethylaniline-N,N): can cause irreversible eye damage

• Rubber Cement: has caused birth defects in laboratory animals

The products used in the prosthetics industry contain chemical ingredients that are of concern by themselves. Some of the chemicals of special concern are styrene, acetone, toluene, and methyl ethyl ketone.

Styrene is an ingredient in many laminating resins. In the survey, 35.1% of technicians use polyester resin 1-3 times per week or more, 75.3% use acrylic resin 1-3 times per week or more, and 71.1% use epoxy resin 1-3 times per week or more. 28.7% wear a respirator or ventilator while laminating and 76.6% use a vacuum system. Depending on the vacuum system available and the amount of contaminants in the air, some technicians may be exposed to styrene. Breathing high levels of styrene can cause nervous system effects such as depression, concentration problems, muscle weakness, tiredness, and nausea. It can also cause eye, nose and throat irritation. In long term testing on animals, liver, kidney, brain and lung damage was experienced. Styrene has also been determined to possibly cause cancer in humans. Some studies have shown that breathing styrene may cause leukemia.⁵

Acetone is used daily by 75.3% of survey respondents while another 15.5% use it 1-3 times per week. Acetone is one of the most commonly used chemicals in the prosthetics industry. If exposed, acetone goes directly into the blood and is carried to all of the organs. In small amounts, it is broken down in the liver and is not harmful.⁵ "Breathing moderate to high levels of acetone for short periods of time, however, can cause nose, throat, lung, and eye irritation, headaches, light headedness, confusion, increased pulse rate, effects on blood, nausea, vomiting, unconsciousness and possible coma, and shortening of the menstrual cycle in women."⁵ Swallowing high levels of acetone can cause unconsciousness and damage to the skin in the mouth. Skin contact results in irritation and damage to the skin. Long term exposure in animal studies have shown kidney, liver, and nerve damage, increased birth defects, and a decrease in a male's ability to reproduce.⁵ A study conducted at an antenatal counseling service in Toronto, Canada from 1987 to 1996, and reported in the August 2000 JAMA, showed that occupational exposure to organic solvents (acetone included) during pregnancy was associated with an increased risk of major fetal malformations. The study found that women exposed occupationally to organic solvents had a 13-fold risk of major malformations as well increased risk for miscarriages in previous pregnancies while working with organic solvents. Also, women reporting symptoms associated with organic solvents during early pregnancy had a significantly higher risk of major malformations than those who were asymptomatic, suggesting a dose-response relationship. ¹⁴

Toluene is another commonly used hazardous chemical found in ambroid, rubber cement and other contact cements or glues. 84.5% of survey respondents use contact cement or other adhesives daily with another 11.3% using it 1-3 times a week. Contact cement or other adhesives were the most commonly used products in the survey. "Toluene affects the brain. Low to moderate levels from long-term exposure can cause tiredness, confusion, weakness, drunken type actions, memory loss, nausea and loss of appetite, and hearing loss. Inhaling a high level of toluene in a short time can make you feel light headed, dizzy, or sleepy. It can cause unconsciousness, and even death. Repeated exposure to high levels can cause permanent brain and speech damage, vision and hearing problems, loss of muscle control, and poor balance. It can also cause memory loss and decreased mental ability. Toluene also effects the kidneys."5 Toluene can cause neurologic problems and retarded growth and development in babies if the mother inhales a high level of toluene during pregnancy. ⁵ Exposure to high levels of toluene has also been shown to increase the chance of spontaneous abortions among female workers. ³³

Methyl ethyl Ketone (2-Butanone) is also used in ambroid and various rubber cements and glues. Methyl ethyl ketone can cause irritation to the nose, throat, skin and eyes. Serious health effects in animals have only been seen at high levels of exposure. At high levels of inhalation, animals have experienced birth defects, loss of consciousness, and death. At high levels of ingestion, rats experienced nervous system effects such as drooping eyelids and uncoordinated muscle movements. ⁵

Carbon fiber and carbon fiber dust were mentioned by many respondents in the survey as a concern and will be discussed briefly. OSHA states that carbon/graphite fibers can cause skin and respiratory irritation, contact dermatitis and possibly chronic interstitial lung disease.³⁰ Carbon fibers commonly in use are greater than six micrometers in diameter making them unlikely to be respirable or able to enter the lungs.30 However, carbon dust created by machining (grinding, routing, and sanding) may be very fine and should be considered respirable. 30 3M states that generally for a dust particle to be respirable it must be less than 10 microns in size.² This suggests that the carbon fibers less than 10 microns may be respirable along with the carbon fiber dust. Carbon fiber dust levels should be controlled below the OSHA permissible exposure limits for inert or nuisance dust, which are 5 mg/m3 respirable fraction and 15 mg/m3 total dust.³⁸

It should be noted that all health effects are based on the amount of exposure. Is the product touching the skin directly? Is the product inhaled or ingested? Are the chemicals in the air above the permissible exposure limits? What safety measures are in place?

EXPOSURE LIMITS

Most of the products studied in this research project are a mixture of various chemical components. Unfortunately, studies have not been done on the finished product, only on the components. MSDS sheets give exposure limits of the various components. In order to understand these exposure limits, some terminology needs to be understood.

"Exposure limits have different names and different meanings depending on who developed them and whether or not they are legal limits. For example, Threshold Limit Values (TLVs) are exposure guidelines developed by the American Conference of Governmental Industrial Hygienists (ACGIH). They have been adopted by many Canadian governments as their legal limits. Permissible Exposure Limits (PELs) are legal exposure limits in the United States."¹⁷

OSHA sets permissible exposure limits (PELS) in the United States. PELs are enforceable by OSHA. PELs are based on an 8-hour time weighted average (TWA) exposure.²⁶ "Time-weighted average (TWA) exposure limit is the time-weighted average concentration of a chemical in air for a normal 8-hour work day and 40-hour work week to which nearly all workers may be exposed day after day without harmful effects. Time-weighted average means that the average concentration has been calculated using the duration of exposure to different concentrations of the chemical during a specific time period. In this way, higher and lower exposures are averaged over the day or week. Short-term exposure limit (STEL) is the average concentration to which workers can be exposed for a short period (usually 15 minutes) without experiencing irritation, long-term or irreversible tissue damage, or reduced alertness."¹⁷ "Workers can be exposed to a maximum of four STEL periods per 8 hour shift, with at least 60 minutes between exposure periods."¹⁹ Ceiling (C) exposure limit is the concentration that should not be exceeded at any time.¹⁷ Usually, PELs and TLVs refer to substances that may be inhaled, although some can be absorbed through the skin or eyes. When skin exposure is possible, the designation "skin" may be listed on the MSDS sheet. ¹⁹

"OSHA currently has 470 Permissible Exposure Limits (PELs) for various forms of approximately 300 chemical substances, many of which are widely used in industrial settings. The current PELs are based on research conducted primarily in the 1950's and early 1960's and, in many cases, do not adequately protect worker health. Therefore, in 1989 OSHA published a final rule for general industry, revising 212 existing exposure limits and establishing 164 new ones. In addition, OSHA proposed in 1992 to apply most of these new and revised limits to construction, maritime, and agriculture. However, in 1992 the 11th Circuit Court of Appeals ruled that OSHA did not sufficiently demonstrate that the new PELs were necessary or that they were feasible. The Court's decision to vacate the new limits forced the Agency to return to the original 1971 limits."²⁷ The American Conference of Governmental Industrial Hygienists (ACGIH) TLVs are generally more protective than OSHA's PEL values. "Many U.S. companies use the current ACGIH levels or other internal and more protective limits."²⁷

The Chemical Abstracts Service of the American Chemical Society assigns CAS Registry Numbers. Each chemical gets a unique identifier although a chemical may go by many different names. ¹⁷ By knowing the CAS number for a chemical, PELs and other chemical information can be obtained through OSHA or the National Institute for Occupational Safety and Health (NIOSH). Appendix D lists the various products used in this study, their chemical components, CAS numbers, OSHA PELs and ACGIH TLVs. As can be seen from Appendix D, PEL's have not been established for many of the chemicals. This data is incomplete and is for informational purposes only.

EXPOSURE CONTROL

MDSD sheets reveal that products are hazardous to the skin, eyes, respiratory system, digestive system and various other organs. They specify PELs for the chemical components in the product, but do not specify how much exposure to the product itself is dangerous. However, they do specify various means to protect employees from exposure. Appendix E lists the exposure control or personal protection measures that are recommended by the MSDS sheets studied. In almost all instances, mechanical ventilation is recommended. From the survey, it was found that only 4.1% of the respondents did not have a ventilation system, and 74.2% of the respondents are at least somewhat satisfied with their ventilation system. These numbers are encouraging, but it is important to know if the ventilation system is maintaining the air contaminants below the permissible exposure limits. To determine if concentrations of airborne contaminants are a respiratory hazard, one should consult with a safety and health professional or an industrial hygienist. They can identify contaminants and measure concentrations.¹ Air monitoring systems are also available. 3M has air monitoring systems available that can be worn by employee throughout the day and then analyzed to determine the chemical composition of the air. 3M claim the devices will meet or exceed ±25% accuracy at a 95% confidence level for many contaminants. ¹

PERSONAL PROTECTION

In addition to mechanical ventilation, the use of personal safety equipment should be encouraged. Protective gloves, safety glasses, facemasks, respirators, and hearing protection are ways to prevent problems from arising in the future. Unfortunately, it may be complicated and confusing to determine what is the best means of protection. Gloves and respirators are two items that are often difficult to determine the best choice for the situation. The following paragraphs will offer some suggestion on the proper gloves and respirators to use in the prosthetics industry.

PROTECTIVE GLOVES

According to NIOSH, dermatologic disorders are one of the top ten leading occupational health problems, primarily a result of workplace exposure to harmful chemical, biologic, and physical agents. The hands are at greatest risk.¹⁶ The most reliable way to eliminate exposure to these harmful agents is through the use of protective gloves. Gloves were recommended on the MSDS sheets for almost all products reviewed, but seldom were specific gloves suggested. Approximately 90% of survey respondents use acetone 1-3 times or more per week, however, only 39% wear latex or vinyl gloves. Unfortunately, latex gloves are effective only against water based solutions and offer little to no protection against organic solvents such as acetone.⁸ Regrettably, chemical resistant gloves were not included on the technician survey. The wearing of any gloves may give a false sense of security. The use of the wrong type of gloves can increase the chance of harm by holding the chemical close to the skin in a warm, moist environment. ⁸

Chemical resistant gloves should be used for products used in the prosthetics fabrication process. An appropriate chemical resistant glove must be chosen based upon amount of degradation, breakthrough time, and permeation rate. ^6,39 Degradation can cause cracking, tearing, or dissolving of the glove material. ⁶ Breakthrough time is the potential usable time; the time before the initial chemical contact until the time when the chemical reaches the inside surface of the glove.^6,39 Permeation rate is the time in which it takes the chemical to diffuse from the outside of the glove to the inside on a molecular level. ³⁹ "The best protective glove is one which demonstrates no significant deterioration upon contact with the specific chemical, and has an acceptably high breakthrough time and a low permeation rate under the conditions of use." ³⁹ Again, research has been done mostly on pure chemicals and most of the chemicals used in industry are mixtures. A chemical mixture may have higher permeation rates than its components. ³⁹

Upon consulting with NIOSH concerning the products used in this study, recommendations are to wear a disposable 4H or Silver Shield glove underneath a thin flexible glove, such as latex. The 4H or Silver Shield glove provides chemical resistance while the latex glove improves dexterity. A 4-hour wearing time is suggested for the 4H or Silver Shield glove and more frequent replacement for the thin glove. ⁷ The University of Toronto Protective Glove Standard also recommends the Silver Shield glove against a wide range of acids, solvents and bases.³⁹ Both the 4H and the Silver Shield gloves are supplied through North Safety Products. The Silver Shield glove is made from Norfoil® which is a lightweight, flexible laminate. It is also available in a more flexible style, Silver Shield Lite. Both types are available in small, medium and large sizes.²⁵ 4H gloves are very similar to the Silver Shield gloves and are offered in 7 different sizes.²⁴ Other gloves on the market offering comparable protection as the Silver Shield or 4H glove would also be acceptable. See Table 6 for breakthrough times for 4 types of gloves for various chemicals. Be advised that no single glove material will protect against all chemicals, no glove material is totally impermeable, and glove performance can vary with product and manufacturer.³⁹

RESPIRATORS

Engineering controls should be the primary method to control airborne contaminants, but when contaminants are above permissible exposure levels or secondary protection is desired, a respirator should be used. OSHA estimates that 5.0 million workers wear respirators occasionally or routinely.³¹ "Respirator use is encouraged, even when exposures are below the exposure limit, to provide an additional level of comfort and protection for workers. However, if a respirator is used improperly or not kept clean, the respirator itself can become a hazard to the worker."²⁸ "Respirators can only provide adequate protection if they are properly selected for the task; are fitted to the wearer and are consistently donned and worn properly; and are properly maintained so that they continue to provide the protection required for the work situation."³¹ Misuse of a respirator can be harmful to the safety and health of the employee. OSHA recommends that a comprehensive respiratory protection program is developed and implemented in each workplace where respirators are used. ³¹ OSHA outlines a respirator protection program online through their web page.³¹ Respirator protection programs can also be recommended through a respirator supplier.

If respirators are not required by OSHA or the employer, but are used voluntarily by an employee, the employer must provide the basic advisory information on respirators, as given in Appendix D of OSHA CFR 1910.134. The employer is also required to have the elements of a written protection program ensuring that the respirator is used correctly and the employee is fit. This does not include the use of dust masks.1 A copy of CFR 1910.134 is included in Appendix F.

A respirator should be chosen based upon the following factors:³¹

• Nature of the hazard, and the physical and chemical properties of the air contaminant

• Concentrations of contaminants

• Relevant permissible exposure limit or other occupational exposure limit

• Nature of the work operation or process

• Time period the respirator is worn

• Work activities and physical/psychological stress

• Fit testing

• Physical characteristics, functional capabilities and limitations of respirators

In the prosthetics field an air purifying respirator would be recommended. Air purifying respirators remove contaminants from the air. Filters or cartridges/canisters are the functional piece of the air purifying respirators. Filters remove particulates from the air while chemical cartridges or canisters remove vapor and gas from the air. Combination cartridges protect against particulates, gases, and vapors. ³¹

Prosthetic technicians are exposed to particulates as well as harmful vapors. From reviewing the 3M Company's Solutions for Occupational Health and Environmental Safety 1999 Resource Guide, ¹ the following guidelines are recommended for respirator selection by the author of this report:

For complete protection against particulates and harmful vapors, a full facepiece air purifying respirator with particulate/organic vapor cartridge would be advised. If contaminant exposure levels are below 10 times the permissible exposure limit a half facepiece respirator is acceptable if the appropriate eye protection is worn. The cartridge must be NIOSH approved for N, R, or P class 95 or 100 particulate filters. The N, R, and P refer to a respirator's ability to filter out oil particles. The 95 and 100 refer to filter efficiency.

For protection against particulates only, a NIOSH approved N, R, or P filter, class 95 or 100 air purifying respirator would be advised. This would be for an employee who is not involved with laminating or working directly with chemicals. This respirator is the dust mask that everyone is familiar with. Dust masks are now available in many styles with many options. Some options include nose clips, odor removing filter material, adjustable straps, and materials to make breathing easier and cooler.

There are many choices for respirators and it is recommended one consult with a respirator supplier, such as 3M, to determine the correct respirator for the application.

HEALTH ISSUES

One of the main goals of this research project was to be able to correlate chronic health issues with the products/chemicals that are used in prosthetics as well as identity the safety practices that are followed by employees. Unfortunately, due to the quantity of variables involved and lack of research time, it was not possible to statistically correlate the health issues with a specific product or safety measure. However, it was determined that the number of headaches, skin rashes, allergies, and hearing loss may be at a level above annual averages in the U.S. (See Table 5). These results indicate the need for further research into the correlation of these specific health issues with product exposures and safety measures.

Headaches:

Research has found that the U.S. national average for headaches from 1990-1992 was 11.48% of the 18-44 age group and 10.19% of the 45-64.9 In the prosthetic technician survey, 15.5% of respondents suffer from headaches. This is 4-5% higher than the national average in both age groups. Exposure to various chemicals may have had an impact on the percentage of headaches from the survey although correlations cannot be established at this time. It is recommended by the author that if an employee suffers from frequent headaches, he should evaluate the amount of exposure to chemicals he is experiencing on a daily basis as well as look at the protective equipment that is being implemented.

Skin Rash & Allergies:

Ten percent of the U.S. population suffers from some type of allergy.12 In the prosthetic technician survey, 21.6% suffer from some type of allergy. Also, in addition to allergies, 12.4% of respondents suffer from some form of skin rash and 1% identified eczema as a chronic problem. Occupational allergy is a term used to describe allergic reactions occurring after working with industrial dusts, vapors, gases or fumes. Eczema may be one form of occupational allergy. Substances like rubber and glue may result in eczema that occurs at the site of contact with the skin.⁴ "The degree of eczema depends on the length of exposure and sensitivity to the substance. Symptoms may show within some weeks - but it can often take months, years, sometimes decades, before an eczema develops. Any part of the skin may become affected, but the most frequent sites are the hands, arms and the face because these tend to be the least protected parts of the body."⁴ Future studies should evaluate the breakdown of the types of allergies and skin rashes. By determining if the allergies or rashes are food, skin, or respiratory related, a better correlation between industry, allergies, and skin rashes can be determined. Given the number of chemicals used that are respiratory and skin irritants, a correlation between working in the prosthetics industry and the number of allergies and skin rashes suffered is likely.

Hearing Loss:

Noise induced hearing loss accounts for the major proportion of hearing loss for people aged 35 to 65. ³⁶ Noise levels are measured in units of decibels (dBA). "An estimated 8 million workers in U.S. manufacturing industries are exposed to potentially hazardous average daily levels of occupational noise at 80 dBA and above. More than 3 million workers in other occupations are exposed to average daily levels above 85 dBA. One U.S. worker in four exposed to 90 dBA over a working lifetime will develop a hearing impairment. Noise-induced hearing loss can be caused by integrated, continuous, or intermittent noise levels of 85 dBA, individual instances of 140 dBA, or short term exposures of 115 dBA. Workers exposed to industrial noise may not manifest noise-induced hearing loss for as many as 10 years after initial exposure." ³⁶

According to NIOSH, the maximum exposure time at 85 dBA is 8 hours and the maximum exposure time at 110 dBA is one minute and 29 seconds. ²³ After reaching maximum exposure time, noise induced hearing loss can occur. As a reference point, consider that normal conversation is 60 dBA, shouting in the ear is 110 dBA, a pneumatic drill is 120 dBA and a jackhammer or power drill is 130 dBA. ²³ According to NIOSH, as long as the 8 hour day time weighted average is below 85 dBA, risk of hearing loss is only 8% over a 40 year lifetime exposure.²⁰ Technicians in the prosthetics field are consistently exposed to noise above 85 dBA and therefore the possibility of hearing loss is likely.

This study found that 12.4% of the respondents suffer from some hearing loss, although only 21.6% of those polled wear hearing protection on a daily basis. In addition, 17.5% of the respondents' facilities did not have hearing protection available. OSHA requires that employees be in a hearing conservation program if they are above the 85 dBA recommended exposure level. The following indicates that a hearing conservation program might be necessary: employees are complaining of the loudness of the environment, normal conversation is difficult, or there are indications of employees losing their hearing. Noise levels can be measured by a sound level meter or a dosimeter. A dosimeter is more accurate in that it stores sounds level measurements and calculates an average. With a dosimeter, a microphone can be attached to the employee's clothing and worn throughout a day. ²⁹ If interested, dosimeters can be rented and facilities can test their own noise level. OSHA is also available for free, on-site testing.

It is recommended by the author that hearing protection is available in areas where loud equipment is used and that employees are encouraged to protect their hearing. Again, many types of hearing protection are available. One should consult with their hearing protection supplier to determine the best hearing protection for the application.

Conclusion / Recommendations

Two hundred surveys were sent nationwide and 97 were returned. Results from the survey and personal comments included with the replies show that technicians are aware of and concerned about safety issues in the workplace. Results indicating a high use of safety glasses and ventilation systems are encouraging. This high use may be due to the availability of the equipment and ease of use as well as immediate results, since particles flying through the air can be seen. The low use of hearing protection and respirators, however, was discouraging. The low results may be due to unavailability of safety equipment or because of the inconvenience of donning the equipment. Also, because short-term effects are not experienced, a person might not be aware of or concerned about possible long-term exposure effects. By having safety equipment on site, educating technicians in the hazards of the chemicals they are using and the long term effects of noise and chemical exposure, and giving proper training on the use of equipment, employees will be more inclined to use safety equipment. Therefore, the author of this report would make the following recommendations:

Recommendations for all prosthetic fabrication facilities

• Each facility should be evaluated to determine if airborne contaminants are below permissible exposure limits.

• All facilities should have an adequate ventilation system or vacuum system to keep airborne contaminants below permissible exposure limits.

• If airborne contaminants are above permissible exposure limits or airborne contaminant concentrations are unknown, respirators should be made available to employees along with proper training.

• MSDS sheets should be available in chemical use areas and MSDS training should be required upon employment.

• Eye protection should be available for all employees.

• Hearing protection should be available for employees in high noise areas.

• Dust masks should be available in all grinding areas in addition to mechanical ventilation.

• Chemical resistant gloves and latex gloves should be available for employees.

Recommendations for future studies

• Conduct a statistically designed study to correlate health issues to product use and safety measures.

• Conduct a study that further breaks down health issues based upon symptoms experienced (i.e. skin cracking on hands, type of headache and when experienced).

• More detailed studies on the chemicals used in the prosthetics industry versus types of gloves and breakthrough time.

• A study to evaluate the types and brands of safety glasses, gloves, dust masks, hearing protection, and respirators that are used in the industry.

Bibliography

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• Adams, PF, GE Hendershot, and MA Marano. "Current Estimates from the National Health Interview Survey, 1996." National Center for Health Statistics. Vital Health Stat Series 10, Vol. 200. (1999).

• Allergies: Nothing to Sneeze At. 31 Dec. 2000 www.mckinley.uiuc.edu.

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