Engineering Controls Database

Control of Hazardous Material and Noise Exposure in Electronics Recycling Operations.

Problem:	Lead (Pb), cadmium (Cd), and other metals are used in the manufacturing of electronic components. These pose a risk to workers involved in recycling of electronic components if the processes are not adequately controlled or the workers are not properly trained and provided appropriate personal protective clothing and equipment. The disassembly and recovery of materials from electronic equipment creates an exposure risk for workers. Air sampling conducted at one recovery operation indicated that exposures can be well in excess of OSHA Permissible Exposure Limits (PELs). In the facility described in the report, the highest exposures occurred to workers during maintenance operations when a three filter bank system of filters used to clean the air was replaced. Airborne concentrations of Cd and Pb measured during filter change-out showed an 8-hour time weighted average of about 150 times the OSHA Permissible Exposure Limit (PEL) for Cd and 15 times the OSHA PEL for Pb for one of the two workers conducting the filter exchange operation. Air samples collected on a second worker showed airborne concentrations of 30 times the PEL for Cd and 4 times the PEL for Pb. In both cases the results showed that the Cd concentrations exceeded the assigned protection factor for the powered air-purifying respirator being used by the workers. An overexposure to Cd was also found during the weekly clean-up operation. While beryllium levels were not consistently high at the facility referenced in the report [EPHB 326-12a], many of the activities that might expose workers to beryllium (such as shredding of removed components) were not conducted on-site. Sampling also indicated exposure risks from surface contamination. Surface wipe and bulk dust samples were also examined at the operation and lead, cadmium and other heavy metals were detected. While there are few established standards available for wipe samples with which to compare these data, and although wipe sample results cannot be used to determine when the contamination occurred, most of the surfaces tested for lead indicated levels exceeding the most stringent criteria. Finally, workers were exposed to risks of hearing loss from sustained noise levels over exposure limits. Measurement of noise levels at the facility examined in the report indicated several measurements exceeding the Recommended Exposure Limit (REL) and Threshold Limit Value (TLV) of 85 dBA. One exceeded the PEL of 90 dBA and 3 other measurements exceeded 50% of the allowable dose requiring that those employees be placed in a hearing conservation program. Engineering controls were not implemented in this case of this hazard, although operators need to be made aware of potential risks.
What this means to you:	Computers and their components contain a number of hazardous substances. Among these are “platinum in circuit boards, copper in transformers, nickel and cobalt in disk drives, barium and cadmium coatings on computer glass, and lead solder on circuit boards and video screens” [Chepesiuk 1999]. The Environmental Protection Agency (EPA) notes that “In addition to lead, electronics can contain chromium, cadmium, mercury, beryllium, nickel, zinc, and brominated flame retardants” [EPA 2008]. Schmidt [2002] linked these and other substances to their use and location in the “typical” computer: lead used to join metals (solder) and for radiation protection, is present in the cathode ray tube (CRT) and printed wiring board (PWB). Aluminum, used in structural components and for its conductivity, is present in the housing, CRT, PWB, and connectors. Gallium is used in semiconductors; it is also present in the PWB. Nickel is used in structural components and for its magnetivity; it is found in steel housing, CRT and PWB. Vanadium functions as a red-phosphor emitter; it is used in the CRT. Beryllium, used for its thermal conductivity, is found in the PWB and in connectors. Chromium, which has decorative and hardening properties, may be a component of steel used in the housing. Cadmium, used in Ni-Cad batteries and as a blue-green phosphor emitter, may be found in the housing, PWB and CRT. Cui and Forssberg [2003] note that cadmium is present in components like chip resistors, semiconductors, and infrared detectors. Mercury may be present in batteries and switches, thermostats, sensors and relays [Schmidt 2002, Cui and Forssberg 2003], found in the housing and PWB. Arsenic, which is used in doping agents in transistors, may be found in the PWB [Schmidt 2002]. Electronics recycling operations, depending on the particular activities conducted, may expose workers to these hazardous substances. The following table presents the various occupational exposure limits established for the five metals of primary interest to the assessment team for the facility in the case report. [img=1] Skin contact with barium, and many of its compounds, may cause local irritation to the eyes, nose, throat and skin, and may cause dryness and cracking of the skin and skin burns after prolonged contact [Nordberg 1998]. Beryllium has been designated a known human carcinogen by the International Agency for Research on Cancer [IARC 1993]. In 1984, NIOSH issued a Current Intelligence Bulletin, which recommended that cadmium and its compounds be regarded as potential occupational carcinogens based upon evidence of lung cancer among a cohort of workers exposed in a smelter [NIOSH 1984]. Early symptoms of cadmium exposure may include mild irritation of the upper respiratory tract, a sensation of constriction of the throat, a metallic taste and/or cough. Short-term exposure effects of cadmium inhalation include cough, chest pain, sweating, chills, shortness of breath, and weakness. Short-term exposure effects of ingestion may include nausea, vomiting, diarrhea, and abdominal cramps [NIOSH 1989]. Long-term exposure effects of cadmium may include loss of the sense of smell, ulceration of the nose, emphysema, kidney damage, mild anemia, an increased risk of cancer of the lung, and possibly of the prostate [NIOSH 1989, Thun et al. 1991, Goyer 1991]. Symptoms of lead poisoning include weakness, excessive tiredness, irritability, constipation, anorexia, abdominal discomfort (colic), fine tremors, and "wrist drop” [Saryan and Zenz 1994, Landrigan et al. 1985, Proctor et al. 1991a]. Overexposure to lead may also result in damage to the kidneys, anemia, high blood pressure, impotence, and infertility and reduced sex drive in both genders [NIOSH 1978]. Metallic nickel compounds cause allergic contact dermatitis [Proctor et al. 1991b]. NIOSH considers nickel a potential occupational carcinogen [NIOSH 2005].
Description of control:	Air in the recycling facility is run through a replaceable filter. The filter change operation is normally performed by two workers (three were involved during the time of the follow-up study because one was in training) who wear disposable Tyvek coveralls, gloves and PAPRs while they remove all three sets of filters, clean the system, and replace the filters. The filter change is a maintenance operation that occurs at approximately monthly intervals during which the ventilation system is shut down and all three sets of filters are removed and replaced. Initially the blanket filter is vacuumed then removed. Then the pocket filters that are located behind the blanket filter are removed and the containment structure for both is vacuumed. Finally the HEPA filters, which are in a separate structure downstream from the fan, are removed and this area is vacuumed. During the initial sampling visit all filters were cleaned by vacuuming and/or by shaking to remove dust, and then reinstalled. The practice of replacing all filters as part of this operation was implemented prior to the follow-up sampling visit and the entire process was wetted with a water spray prior to filter removal. This operation was of particular interest because of concern expressed by management and workers and anticipation of elevated exposures. Before the follow-up visit, modifications were made to the procedure used for filter cleaning. The recommended changes included: 1) the immediate bagging and disposal of used filters rather than attempting to clean and re-use them; 2) the use of a water spray to suppress dust during the filter change operation; and 3) the use of HEPA vacuums and wet mopping to remove dust from the floor and work surfaces. The procedure was modified by the addition of a “spray down” step in which all filters were wetted with a water mist prior to removal, and the filters were then immediately bagged in plastic for disposal rather than being cleaned for re-use.
Engineering and Physical Hazard Report Numbers:	326-12A;
References:	Chepesiuk R [1999]. Where the chips fall: environmental health in the semiconductor industry. Environ Health Perspect. 107:A452–A457. Cui J, Forssberg E [2003]. Mechanical recycling of waste electric and electronic equipment: a review. J Hazard Mater. 99:243–263. EPA [2008]. eCycling. Available on-line at http://www.epa.gov/ecycling/. Accessed June 3, 2008. Goyer RA [1991]. Toxic effects of metals. In: Amdur ML, Doull J, Klaassen CD (eds.) Casarett and Doul’s Toxicology, pp. 623–680. IARC [1993]. IARC monographs on the evaluation of carcinogenic risks to humans: beryllium, cadmium, mercury, and exposures in the glass manufacturing industry. Vol. 58. Lyon, France: World Health Organization, International Agency for Research on Cancer. Landrigan PJ, Froines JR, Mahaffeyet KR [1985]. Body lead burden: summary of epidemiological data on its relation to environmental sources and toxic effects. In: Dietary and environmental lead: human health effects. Amsterdam: Elsevier Science Publishers. NIOSH [1978]. Criteria for a recommended standard: occupational exposure to inorganic lead. Revised criteria – 1978. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 78-158. NIOSH [1984]. Current intelligence bulletin #42: Cadmium. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 84-116. NIOSH [1989]. Occupational health guidelines for chemical hazards. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH)/DOL (OSHA) Publication No. 81-123 and supplements 88-118, 89-104. NIOSH [2005]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2005-149. Available online at http://www.cdc.gov/niosh/npg/. Accessed June 6, 2008. Nordberg G, ed. [1998]. Barium. In: Metals: chemical properties and toxicity. Chapter 63. In: Stellman, JM, ed. Encyclopedia of occupational health and safety. 4th ed. Vol. 2. Geneva: International Labor Office. Pp. 63.8-63.9. Proctor NH, Hughes JP, Fischman ML [1991a]. Lead. In: Chemical hazards of the workplace. 3rd ed. Philadelphia, PA: J.B. Lippincott Company, Philadelphia, pp 353 357. Proctor NH, Hughes JP, Fischman ML [1991b]. Nickel and inorganic compounds. In: Chemical hazards of the workplace. 3rd ed. Philadelphia, PA: J.B. Lippincott Company, Philadelphia, pp 422-424. Saryan LA, Zenz C [1994]. Lead and its compounds. In: Occupational medicine. 3rd ed. Chicago, IL: Mosby-Year Book, Inc. Schmidt CW [2002]. e-Junk explosion. Environ Health Perspect. 110:A188–A194. Thun MJ, Elinder CG, Friberg L [1991]. Scientific basis for an occupational standard for cadmium. Am J Ind Med. 20:629-42.
NAICS Codes:	562920
Keywords:	barium barium beryllium beryllium cadmium cadmium component disassembly component disassembly electronics electronics glass breaking operations glass breaking operations lead and nickel lead and nickel packaging and shipping. packaging and shipping. receiving and sorting receiving and sorting Recycling Recycling respirable particulates respirable particulates
How well does this control work?	Measurements made during the follow-up indicated significant reductions in the levels of airborne contaminants during this modified filter replacement operation although respiratory protection during the filter change operation continues to be necessary and other improvements are needed. Modifications were made to the procedure used for the filter change operation after the initial monitoring of airborne particulate. The results of these changes would appear to be a dramatic reduction in airborne particulate. The follow-up measurements indicate levels of Ba, Be, Pb and Ni well below their respective exposure limits. Eight-hour TWAs based on two task-based Cd measurements of 7.8 and 12.9 µg/m3 were 3.5 and 6.1 µg/m3, respectively. The former exceeds the OSHA Action level for cadmium of 2.5 µg/m3, while the latter exceeds the PEL of 5 µg/m3. Measurements of respirable Cd were below the TLV of 2 µg/m3 for that entity. Comparing the geometric means of the 8-hour TWA personal breathing zone cadmium exposures shows the reduction achieved by the change in work practices. The geometric mean of the two 8-hour cadmium TWAs from the sampling prior to implementation of the controls was 357 µg/m3. The geometric mean of the four 8-hour cadmium TWAs from the post-implementation sampling was 0.375 µg/m3. This indicates a reduction of 99.9%, although samples were too small to establish statistical significance.