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HEXAVALENT CHROMIUM OVERVIEW

HEXAVALENT CHROMIUM OVERVIEW. 29 CFR 1926.1126 CHROMIUM (VI) Susan Harwood Grant # 46E6 – HT34. Background Information. Chromium is a metal that exists in several oxidation or valence states, ranging from chromium (-II) to chromium (+VI).

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HEXAVALENT CHROMIUM OVERVIEW

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  1. HEXAVALENT CHROMIUM OVERVIEW 29 CFR 1926.1126 CHROMIUM (VI) Susan Harwood Grant # 46E6 – HT34

  2. Background Information • Chromium is a metal that exists in several oxidation or valence states, ranging from chromium (-II) to chromium (+VI). • Chromium compounds are very stable in the trivalent state and occur naturally in this state in ores such as ferrochromite, or chromite ore. • The hexavalent, Cr(VI) or chromate, is the second most stable state. It rarely occurs naturally; most Cr(VI) compounds are man made.

  3. Background Information • OSHA has determined that the PEL of 5 µg/m3 is technologically feasible for all affected welding job categories • OSHA has concluded that no carbon steel welders are exposed to Cr(VI) above 5 µg/m3, with the exception of a small portion of workers welding on carbon steel in enclosed and confined spaces. • Many welding processes, such as tungsten-arc welding (TIG) and submerged arc welding (SAW), already achieve Cr(VI) exposures below the PEL because they inherently generate lower fume volumes.

  4. Is Chrome a Carcinogen or Necessary Element? • Chrome III is an essential nutrient for maintaining blood glucose levels • Chrome VI is classified as a known human carcinogen

  5. Health Effects • Cancer • Hexavalent chromium is considered a potential lung carcinogen. • Studies of workers in the chromate production, plating, and pigment industries consistently show increased rates of lung cancer. • Insoluble forms such as zinc chromate are the most potent • 20 year cancer latency

  6. Health Effects • Ingestion Hazards • Erosive to stomach • Hemorrhaging and death are likely • Treatment for ingestion - dilution with milk or water and/or asorbic acid. This should only be given by someone qualified in first aid. • Ingestion of ascorbic acid to reduce Cr VI to Cr III will work, but may cause renal failure (conversion of ascorbic acid to oxalate plugs the kidneys) • Recommended that you seek medical assistance first.

  7. Health Effects • Eyes • Direct eye contact with chromic acid or chromate dusts can cause permanent eye damage. • Treatment for eye contact – Flush eye(s) for 15 min. Seek medical assistance. • Respiratory Tract • Hexavalent chromium can irritate the nose, throat, and lungs. • Repeated or prolonged exposure can damage the mucous membranes of the nasal passages and result in ulcers. • In severe cases, exposure causes perforation of the septum (the wall separating the nasal passages).

  8. Health Effects • Skin • Prolonged skin contact can result in dermatitis and skin ulcers. • Some workers develop an allergic sensitization to chromium. In sensitized workers, contact with even small amounts can cause a serious skin rash. • Kidney damage has been linked to high dermal exposures. • Treatment for skin contact - Irrigate with water • Possible use of 10% ascorbic acid topically (the acid reduces/changes Cr VI to Cr III) • Recommended that you seek medical assistance first.

  9. New Cr VI OSHA Standard • Suit by Public Citizen Health Research Group; Paper, Allied Industrial, Chemical, and Energy Workers Union (1997 & 2002) • 4/2/2003 - 3rd Circuit Court of Appeals ruling for OSHA Cr(VI) proposal to be published by 10/4/2004 and standard by 1/18/2006 • 2/28/2006 - Final Rule published

  10. Greater Risk Than Asbestos • Cancer risk from Cr (VI) at new PEL is higher than asbestos risk at asbestos PEL • Asbestos: 6.7 deaths per 1000 workers • Benzene: 10 deaths per 1000 workers • Chrome VI: 10-45 excess lung cancer deaths per 1000 workers for 45 years of exposure at new PEL of 5 ug/m3

  11. Past Cr VI Sampling • Under the old PEL: • little sampling was performed; • Chrome plating was the main focus • Some overexposures were noted • Little welding sampling was performed • A few spray painter exposures were evaluated • They were VERY HIGH. • Painting a plane in a bunker was 1000 X the PEL • Consultation found 3250 ug/m3, 650 X the new PEL • Not much prior sampling for Cr VI exposures

  12. Coverage • General Industry • Basic difference: Construction and Shipyards Cr VI standards lack sections on • Regulated Areas • Housekeeping

  13. Scope • This standard applies to occupational exposures to chromium (VI) in all forms and compounds in construction, except: • Exposures that occur in the application of pesticides; • Exposures to portland cement; or • Where the employer has objective data demonstrating that a material containing chromium or a specific process, operation, or activity involving chromium cannot release dusts, fumes, or mists of chromium (VI) in concentrations at or above 0.5 µg/m³ as an 8 hour time weighted average (TWA) under any expected conditions of use. 29 CFR 1926.1126(a)

  14. What is Covered? • Welding - Stainless Steel • Welding - Carbon Steel • Painting • Woodworking • Refractory Brick Restoration & Maintenance • Hazardous Waste Site Work • Industrial Rehabilitation and Maintenance • Portland Cement Producers – Portland Cement? • Ready Mix Concrete – Portland Cement? • Precast Concrete Products – Portland Cement?

  15. Welding • Nearly half the workers covered under the new standard are welders • Chromium in steel is oxidized to Cr VI by high welding temperatures • 6,000 - 8,000° C for the SMAW, GTAW, GMAW, FCAW and SAW processes • The hotter the process and the more oxygen that is present, more fume is generated

  16. Welding • Overexposures are POSSIBLE when welding stainless steel or high chrome steel and proper procedures are not followed. • Stainless steel has between 10.5% - 27% chromium • Nickel is also present in some types of stainless

  17. Welding • Potential for overexposure when welding CARBON steel and proper procedures are not followed. • Position of head during welding is number one problem • Anywhere the welding fume is more confined, such as welding in a tight corner • Reason: 10% of carbon steel has chromium in more than trace amounts

  18. Welding • Stick welding: High likelihood of overexposure to Cr VI • 50% of total Cr produced is Cr VI ( FR pg 10262 col 3) • TIG & MIG generates lower fume amounts • 4% of total Cr produced from MIG is Cr VI

  19. Welding • Submerged arc generates lower fume amounts • Conclusion: Switch to MIG from stick if you can

  20. Definitions • Action level - 2.5 µg/m³ (8-hour TWA). • Permissible Exposure Limit - 5 µg/m³ (8-hour TWA). • This has been lowered from the past level of 52 micrograms per cubic meter of air (52 µg/m³). 29 CFR 1926.1126(b)

  21. Definitions • Objective data means: • Information such as air monitoring data from industry-wide surveys; or • Calculations based on the composition or chemical and physical properties of a substance 29 CFR 1926.1126(b)

  22. Exposure Determination • Each employer who has a workplace or work operation covered by this section shall determine the 8-hour TWA exposure for each employee exposed to chromium (VI). • This determination shall be made in accordance with either of the following methods: • Scheduled Monitoring Option • Performance-oriented Option 29 CFR 1926.1126(d)

  23. Exposure Determination • Scheduled Monitoring Option • Perform initial monitoring to determine the 8-hour TWA exposure for each employee. • Additional monitoring when: • There has been any change that may result in new or additional exposures to chromium (VI), or • When the employer has any reason to believe that new or additional exposures have occurred. 29 CFR 1926.1126(d)(2)

  24. Exposure Determination • Scheduled Monitoring Option • Representative sampling may be performed instead of sampling all employees in order to meet this requirement. • In this case, the employer shall sample the employee(s) expected to have the highest chromium (VI) exposures.

  25. Exposure Determination • If samples show < Action Level • May discontinue monitoring • If samples show ≥ Action Level • Periodic monitoring every six months • If samples show ≥ Permissible Exposure Level • Periodic monitoring every three months • Additional monitoring where process has changed 29 CFR 1926.1126(d)(2)

  26. Exposure Determination • Performance-oriented Option • The employer shall determine the 8-hour TWA exposure for each employee on the basis of any combination of: • Air monitoring data; • Historical monitoring data (prior to 5/30/2006); or • Objective data. 29 CFR 1926.1126(d)(3)

  27. Employee Notification • If sampling shows > PEL, 5 working days to post results or provide in writing • Where sampling shows > PEL, Employer must describe in the written notification the corrective action being taken to reduce employee exposure to or below the PEL 29 CFR 1926.1126(d)(4)

  28. Accuracy of Sampling • Accuracy • Method and analysis +/- 25% w/ a CI of 95% • Example would be the OSHA ID-215 Method 29 CFR 1926.1126(d)(5)

  29. Observation of Monitoring • Where air monitoring is performed to comply with the requirements of this section • Provide affected employees or their designated representatives an opportunity to observe. • The employer shall provide the observer with clothing and equipment and shall assure that the observer uses such clothing and equipment and complies with all other applicable safety and health procedures. 29 CFR 1926.1126(d)(6)

  30. Methods of Compliance • Use engineering and work practice controls to reduce and maintain employee exposure to or below the PEL. • When not sufficient enough, Use of respiratory protection in Addition. • No exposure above the PEL for 30 or more days per year or not feasible, Use of respiratory protection alone to comply. 29 CFR 1926.1126(e)

  31. Methods of Compliance • No rotation of employees to different jobs to achieve compliance with the PEL.

  32. Engineering Controls • To the extent feasible, designed to eliminate or reduce exposure to hazards based on the following principles: • If feasible, design the facility, equipment, or process to remove the hazard and/or substitute something that is not hazardous or is less hazardous. • If removal is not feasible, enclose the hazard to prevent exposure in normal operations. • Where complete enclosure is not feasible, establish barriers or local ventilation to reduce exposure to the hazard in normal operations.

  33. Elimination by Design • Some examples of designing facilities, equipment, or processes so that the hazard is no longer present are: • Redesigning, changing, or substituting equipment to remove the source of excessive temperature, noise, or pressure; • Redesigning a process to use less toxic chemicals; • Redesigning a workstation to relieve physical stress and remove ergonomic hazards; and • Designing general ventilation with sufficient fresh outdoor air to improve indoor air quality and generally to provide a safe, healthful atmosphere.

  34. Enclosure of Hazards • When you can not remove a hazard and cannot replace it with a less hazardous alternative, the next best control is enclosure. • While this may control employee exposure during production, it may not control exposures during maintenance.

  35. Enclosure of Hazards • Some examples of enclosure designs are: • Complete enclosure of moving parts of machinery; • Complete containment of toxic liquids or gasses from the beginning of the process using or producing them to detoxification, safe packing for shipment, or safe disposal of toxic waste products; • Glove box operations to enclose work with dangerous micro-organisms, radio nuclides, or toxic substances; and • Complete containment of noise, heat, or pressure.

  36. Barriers or Local Ventilation • When the potential hazard cannot be removed, replaced, or enclosed, the next best approach is a barrier to exposure, or, in the case of air contaminants, local exhaust ventilation to remove the air contaminant from the workplace. • This engineered control involves potential exposure to the worker even in normal operations, consequently, it should be used only in conjunction with other types of controls, such as safe work practices designed specifically for the site condition and/or personal protective equipment.

  37. Welding Controls • Fume extractor for stick and MIG/TIG welding on stainless steel • Fume extractor for enclosed welding on any kind of steel • Weld using lower temperatures • Avoid stick welding on steel containing chrome, if possible

  38. How is welding fume controlled? • Change the welding procedures; • Stick to MIG or even better TIG • Use welding wires/rods designed for lower fume generation; • Change power sources; • Change shielding gases; or • Fume removal / extraction.

  39. Fume Removal / Extraction • Low Vacuum (High Volume) • Low Vacuum systems remove a large amount of air at low velocity and low vacuum pressure. • In welding fume extraction, low vacuum systems use articulated “arms” roughly 8 inches in diameter and can be from 12 to 18 inches from the welding arc. • These arms typically draw between 600 and 900 CFM per arm. • If access to the joint prevents the use of fume guns or suction heads, low vacuum may be the better solution. • If the weldment smokes considerably after welding due to die oils or paint, fume guns will not work since they are removed after welding.

  40. Low Vacuum (High Volume) • Mobiflex 100-NF Portable Fan • For hard to reach areas, exhaust the fume • Connect to 6 in. diameter, 16 ft. long hose set with magnet mounted hood exhaust or extension hose set. • Does not provide filtration.

  41. Low Vacuum (High Volume) • Mobiflex 200-M Base Unit - Mobile Welding Fume Extractor • A portable, low vacuum/high volume disposable filtration system designed for intermittent or continuous extraction and filtration of welding fumes. • On-board internal extraction fan and is designed specifically for weld applications. • The particulate is collected on the inside of the cartridge, minimizing exposure to particulate during filter maintenance and disposal.

  42. Fume Removal / Extraction • High Vacuum (Low Volume) • High Vacuum systems capture fume as close to the arc as possible using integrated fume extraction guns or heads that use small diameter hose 1.5–1.75 inches, about 4 to 6 inches from the welding arc. • These systems use much smaller hose or duct because they draw only between 35 and 150 CFM. • Fume is captured before it reaches the operators breathing zone. • Using fume guns, the suction automatically follows the arc, eliminating repositioning necessary with low vacuum arms. • Since only a small volume of air is processed, the strain on heating and cooling systems is minimal. • Portable and mobile high vacuum units are smaller and less expensive than mobile low vacuum units.

  43. High Vacuum (Low Volume) • Miniflex - Portable Welding Fume Extractor • A portable, high vacuum, low volume system specifically designed for the removal and filtration of welding fumes. • It can be completely disassembled in a matter of minutes for cleaning and maintenance. • With an automatic start/stop function, the unit automatically turns on and off during welding. • It can be used in confined spaces and other locations that are not accessible with other welding fume extractors.

  44. Work Practice Controls • Position of head during welding operations • When welding outside, having the wind at your back with the fumes being pushed away from your head. • Preplan your work.

  45. Some Painting Controls • Chromates provide excellent corrosion control. • With what data exists, airborne spray painting exposures are high. • Recommendations: • Substitute with non-Cr VI paint, if possible • Conduct spray painting in an extremely well-designed and maintained booth. (Think of controlling lead-based spray paint exposures, but having to control 10 times better.) • Airline respirators

  46. Some Painting Controls • Ventilated grinders have been designed for silica and lead exposures • Some grinders have a ventilated shroud on the grinder or needle gun, others may also have a perforated grinder disk • If the paint contains zinc chromate or other chromates, Cr VI exposures will be high

  47. Some Painting Controls • Ventilated tools, ventilated enclosures, and increased levels of PPE are recommended • Use Paint strippers to eliminate airborne exposures

  48. Personal Protective Equipment • When exposure to hazards cannot be engineered completely out of normal operations or maintenance work, and when safe work practices cannot provide sufficient additional protection, a further method of control is using protective clothing or equipment. • These include face shields, steel-toed shoes, hard hats, respirators, hearing protection, gloves and safety glasses.

  49. Respiratory Protection • Provide respiratory protection for employees during: • Installing or implementing feasible engineering and work practice controls; • Work operations where exposed above the PEL for fewer than 30 days per year and the employer has elected not to implement engineering and work practice controls to achieve the PEL; or • Emergencies. • Where respirator use is required by this section, the employer shall institute a respiratory protection program in accordance with 29 CFR 1910.134. 29 CFR 1926.1126(f)

  50. Respiratory Program Requirements 29 CFR 1910.134

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