1. EZVV Hexavalent Chromium Update 17 Jan 18
Air Force Life Cycle Management Center
Acquisition Environmental and Industrial Facilities Division
Birthplace, Home & Future of Aerospace
EZVV Hexavalent Chromium Update 17 Jan 18
Christine R. Knezevich, CIH – Occupational Health Manager
Acquisition Environmental & Health Risk Management Branch (AFLCMC/EZVV)
U. S. Air Force
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2. Hexavalent Chromium (Cr+6) Summary
Hexavalent chromium compounds (e.g., chromic acid, etc.) are excellent corrosion inhibitors.
Hexavalent chromium is regulated as a known human carcinogen in the U.S. under environmental (i.e., Environmental Protection Agency or EPA) and health & safety (Occupational Safety & Health Administration or OSHA) laws.
A number of Cr+6 compounds including chromium trioxide have been banned in the European Union (EU) with “sunset” dates beginning in September The aerospace industry has been recommended for a number of exemptions (“authorizations”).
The following slides provide an update to Cr+6 aerospace issues including the USAF Cr+6 authorization process.
Chromium trioxide is the acidic anhydride of chromic acid. It is essentially chromic acid without water. So it is hexavalent chromium. It can be marketed as chromic acid. Often to save on chemical transportation costs, dry chromic acid flake (chromium trioxide) is shipped and the company who receives it puts it into solution for use or further processing.
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3. U.S. Hexavalent Chromium Regulatory Update
Clean Air Act: Cr+6 National Emission Standard for Hazardous Air Pollutants (NESHAPs) has been in place for affected industries (e.g., electroplating). There are no recent changes.
Clean Water Act: The EPA is conducting a 2016 – 2017 review of the metal finishing effluent guidelines.
Safe Drinking Water Act (SDWA): The EPA has required a selected number of water systems to perform Cr+6 monitoring for 1 year as part of a regulatory review. Currently, only total chromium (not Cr+6) is regulated under SDWA. In 2014, California became the first state to set a drinking water limit for Cr+6.
OSHA’s Cr+6 Standard remains unchanged. In 2013, OSHA issued a Fact Sheet on “Controlling Exposure to Hexavalent Chromium in Aerospace and Air Transport Painting.”
Clean Water Act (CWA): “The EPA is conducting a preliminary review of the Metal Finishing Category. EPA solicits data and information regarding the discharge and treatment of metals, particularly chromium, nickel, and zinc, in addition to cadmium, copper, lead, silver, and any others, to POTWs by metal finishers, as well as any other information believed to be relevant to EPA’s review.” See
SDWA total chromium maximum contaminant level (MCL) is 100 micrograms (ug)/L. See Cr+6 monitoring requirements under the EPA Unregulated Contaminant Monitoring Regulation (UCMR 3). See April 24, 2017 announcement at
The California MCL for Cr+6 is 10 ug/L.
H.R. Bill 1068 – SDWA revisions proposed include the review of 10 contaminants every 3 years. Currently, 5 contaminants are reviewed every 5 years. Also the bill calls for a review of perchlorates & perfluorinated compounds for regulation.
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4. OSHA Hexavalent Chromium Standard
The standard has an 8 hour time weighted average Cr+6 exposure of 5 micrograms (ug)/m3.
It requires periodic monitoring at least every 6 months if initial monitoring shows employee exposure at or above the action level of 2.5 ug/m3 as an 8 hour time weighted average.
Respiratory protection must be provided.
Appropriate personal protective clothing and equipment if skin or eye contact is a likely to be a hazard must be provided.
Medical surveillance to employees who are or may be exposed at or above the action level for 30 or more days/year, and at termination of employment is required.
Employers are prohibited to use worker rotation as a method to achieve compliance with the exposure limit.
OSHA did not specify what exactly needed to be in terms of medical surveillance. The guidance recommended was to focus on skin and the respiratory system. Biomonitoring is not required, but there is a ACGIH biological exposure index (BEI) of total chromium in urine (at the end of shift at the end of the week.) However, there are dietary sources of trivalent chromium that will be picked up in urine. So you can’t use BEI in isolation. The only employees that I previously had in a biomonitoring program (in industry) with elevated chromium in urine were NOT production or maintenance workers. One was an administrative customer service employee. The other was a technical field/sales representative. Both employees admitted to starting diets with vitamins containing chromium.
Housekeeping Programs – yes, OSHA counts “5S” as housekeeping. Wipe sampling in break areas may be requested by a local OSHA office (not in the standard) or a local union.
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5. EU Hexavalent Chromium Regulatory Update
The European Chemical Agency (ECHA) regulates chemicals under its Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation.
The “sunset date” or ban date for chromium trioxide is September 21, There are 2017 – 2019 sunset dates for various hexavalent chromium compounds, such as chromates, used in the aerospace industry.
A number of surface treatment chemical manufacturers have applied for and been recommended for exemptions or “authorizations” for the use of Cr+6 compounds in the aerospace and automotive industries. The exemptions have end dates. It is anticipated that all Cr+6 authorizations will be issued by the first quarter of 2018.
ECHA’s Committees for Risk Assessment (RAC) and Socio-Economic Analysis (SEAC) have adopted 19 final opinions for recommending authorization for the use of hexavalent chromium in aerospace and surface treatment industries. See Annex to a News Alert ECHA/NA/16/37, Helsinki, 13 December 2016; saved on the EZVV Shared Drive under HAZMAT (Chromium & Hexavalent Chromium) Folders. I know that there were 26 proposed authorizations, but the Annex announcement mentions 19 final authorizations. See also
The authorization end dates are 7 years from the original sunset dates of the chemicals. The original sunset dates are from 2017 – The sunset date of chromic acid is Some of the chromate sunset dates are in 2019.
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6. US EPA Regulatory Activities
In last couple of years, the EPA has been reviewing the way that it is regulating hexavalent chromium compounds and metal finishing as a whole.
The metal finishing effluent guidelines date back to the 1980s and do not reflect current science or technologies.
To understand the current metal finishing effluent guidelines, you have to understand conversion coatings, as defined by the EPA.
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7. Conversion Coatings: US Regulatory Definitions
Per the EPA, a conversion coating refers to the application of a coating to previously deposited metal or basis metal for increased corrosion protection, lubricity, preparation of the surface for additional coatings or formulation of a special surface appearance. This includes chromating, phosphating, metal coloring and immersion plating.
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8. Conversion Coatings: US Regulatory Definitions
Chromating – chromium compounds deposit at the surface of the metal form a highly corrosion resistant surface.
Phosphating – Surface of the substrate metal is converted into phosphate compounds. The bath is primarily phosphoric acid with certain metals such as titanium and accelerators including nickel.
Coloring – Converts the metal surface to an oxide or other insoluble metal compound that has the desired color.
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9. Conversion Coatings: US Regulatory Definitions
Immersion Plating – Surface of the base metal is displaced by a second metal. The plating metal deposits onto the base metal as elemental metal, not an oxide or other compound. It is used to plate zinc or zinc/tin onto aluminum. Sodium hydroxide and zinc oxide powder form the bath. Zinc oxide is reduced and goes into solution as zincate ion. The electrochemical potential between the aluminum & zinc drives the zinc to plate out onto the aluminum. The process occurs at ambient temperature & at a pH near 13.
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10. If Related Wastewater Is Discharged To A POTW .
The water discharge is subject to metal finishing pre-treatment standards [Reference: 40 CFR Part 433]
The EPA defines the following 6 processes as metal finishing:
Electroplating
Electroless plating
Anodizing
Coating (chromating, phosphating & coloring)
Chemical etching and milling
Printed circuit board manufacture
Exemption: Point Source Categories for
specific industries (i.e., foundries, etc.)
The Point Source Industry Standards include:
Nonferrous metal smelting and refining [Reference: 40 CFR Part 421]
Coil coating [Reference: 40 Part 465]
Battery manufacturing [Reference: 40 Part 461]
Iron and steel [Reference: 40 Part 420]
Metal casting foundries [Reference: 40 Part 464]
Aluminum forming [Reference: 40 Part 467]
Copper forming [Reference: 40 Part 468]
Plastic molding and forming [Reference: 40 CFR Part 463]
Nonferrous forming [Reference: 40 CFR Part 471]
Electrical and electronic components [Reference: 40 Part 469]
Metallic platemaking and grauvure cylinder preparation conducted within or for printing and publishing facilities or to existing indirect discharge job shops and independent printed circuit board manufacturers [Reference: 40 CFR Part 433]
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11. Conversion Coatings: Summary
BOTTOM LINE:
Over last couple of years, the EPA has announced that it is reviewing and updating the metal finishing effluent guidelines, which can impact the use of hexavalent chromium and its alternatives.
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12. Conversion Coatings: Waste Considerations
F019 hazardous waste is wastewater treatment sludge from the chemical conversion coating (i.e., chromating, phosphating, metal coloring and/or immersion plating) of aluminum with these exceptions/exemptions:
Zirconium phosphating in aluminum can washing when such phosphating is an EXCLUSIVE conversion coating process with no chromium or cyanide in the zirconium phosphating solution. “Exclusive” means not combined with other processes that use hazardous constituents (e.g. electroplating, chromating, etc.) [Reference: 40 CFR ]
Aluminum parts in vehicles
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13. Chrome Free Alternatives: Environmental Considerations
The EPA issued a 2003 determination that PreKote, a non-chromic surface treatment used on Air Force aircraft, is NOT subject to metal finishing effluent guidelines.
The EPA issued a 2016 determination that “zirconization” was a conversion coating & subject to metal finishing effluent guidelines.
Smart/self healing coatings: There have been demonstrations using nanomaterial modified primers in corrosion inhibiting coatings. The corrosion inhibitor is contained in nanospheres, which are activated when the coating is damaged. The environmental concern is the water solubility of the inhibitor.
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14. Chrome Free Alternatives: Environmental Considerations
The Naval Air Systems Command has patented trivalent chromium surface treatments (including an “active aluminum primer” or Cr+3 treated aluminum particles in an epoxy primer) that have worked on aluminum/aluminum alloys.
Environmental Concern: Cr+6 has been found on Cr+3 conversion coatings. The formation of Cr+6 is thought to be due to bath pH and the use of aggressive oxidizing agents, such as peroxide compounds. To combat this problem, more robust Cr+3 passivation systems have been developed that limit immersion time, lower bath pH, lower working temperature, and do not rely on oxidizers.
Hazardous waste and wastewater disposal considerations remain with Cr+3 conversion coatings.
Originally peroxide was added to increase corrosion protection.
Complexing agents are critical:
Cr+6 formation is greater on Cr+3 conversion coatings prepared with an oxalic acid treating agent vs. those prepared with formic acid and acetic acid treating agents. Also Cr+6 conversion is enhanced with the addition of bivalent cobalt and nitrate anion in the treating agent, esp. if oxalic acid is used. The addition of hydroxyl compound D-gluconic acid in the treating agent reduces Cr+6 formation.
References:
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15. Chrome Free Alternatives Concerns
What are the health and safety concerns associated with chrome free alternatives? Are carcinogens still being used?
How are the chrome free chemicals regulated? Are “Chemicals of Concern” (Dept. of Homeland Security) or “List I and II chemicals (Drug Enforcement Administration) being used? What are compliance requirements?
What equipment change-over is necessary, and what is the time involved? What are health & safety considerations with the new equipment?
What is done with existing craft/systems that utilize hexavalent chromium products?
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16. Hexavalent Chromium Authorization Process
Where no proven alternative to Cr6+ exists, the PM will obtain AF Corrosion Control and Prevention Executive (CCPE) concurrence on all approval requests involving corrosion control prior to submitting an authorization request to the PEO. A package to secure AF CCPE coordination and document the PEO authorization includes the following elements:
Authorization Form: Complete Sections A, B and C of the Authorization to Use Hexavalent Chromium form  available at the AFLCMC ESOH Central SharePoint site.
Exemption: Systems at Milestone A after May 2011.
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17. Hexavalent Chromium Authorization Process
Memo for Record
Document determination and supporting rationale
Prepared by PM’s staff, endorsed by PCO and legal
Authorization Package
Authorization to Use Hexavalent Chromium Form
Plan of Action
Life cycle events where Cr+6 can be assessed
If Cr+6 is used in a transition period, identify implementation plan
If alternatives are pending approval, state major decision points for the alternative(s); Test decisions, approvals, etc.
Should be consistent w/ other program documents (CPCP)
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18. EZVV Hexavalent Chromium Update
THANK YOU FOR YOUR ATTENTION!
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