Two Steps Closer to Harmonization

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The United States has made two giant leaps toward international harmonization earlier this year, but still has a long way to go…

Elimination of the ORM-D Classification

Thirty years ago, the U.S. Department of Transportation’s Research and Special Programs Administration (RSPA) published its most significant rulemaking, HM-181, and adopted the international standards of the United Nations’ Recommendations on the Transport of Dangerous Goods Model Regulations (UN Orange Book).


At that time, RSPA eliminated four of five Other Regulated Material (ORM) classifications.  Hazardous materials classified as ORM-A exhibited anesthetic, irritating, noxious, or other toxic properties.  ORM-B hazardous materials were those that could cause significant damage to the transport vehicle and included substances like many corrosive solids.  ORM-C hazardous materials had other inherent characteristics that caused them to be regulated in transportation (e.g., wet cotton), and hazardous substances and hazardous wastes were classified as ORM-E.

RSPA elected to keep hazard class, ORM-D (Consumer Commodities), which were limited quantities suitable for retail distribution and intended for personal care or household use.  Flammable and non-flammable aerosols having a volumetric capacity of not more than 1.0 liter were entitled to significant regulatory relief in the United States when reclassified and marked as Consumer Commodity ORM-D.


However, the use of the ORM-D marking caused aerosol manufacturers and distributors to be out of synch with international standards, thereby putting them at a significant competitive disadvantage.  Many firms had maintained two sets of packaging: one marked Consumer Commodity ORM-D for U.S. markets, and the other Limited Quantity for international shipments.

The elimination of the ORM-D mark levels the playing field and harmonizes U.S. and international consignments of aerosols and other limited quantities of dangerous goods.    Limited quantities are smaller quantities of dangerous goods for which a packaging exception applies.  Instead of using expensive UN approved packagings, strong outer packagings may be used in lieu.  Qualifying dangerous goods are further excepted from the marking of the proper shipping name and identification number for surface and ocean transport.  U.S. domestic shipments of limited quantities will continue to enjoy relief from the requirements for dangerous goods declarations for surface shipments by road and rail but will require dangerous goods declarations for air and ocean transport.

Additional exceptions from stowage, segregation (or separation from other dangerous goods) and marine pollutant marking requirements will also apply.

Proposed adoption of GHS Revision 7

Another significant advance toward international harmonization was made when the U.S. Occupational Safety and Health Administration (OSHA) published a Notice of Proposed Rulemaking (NPRM) in the Federal Register on February 16, 2021.  

OSHA is proposing to modify the Hazard Communication Standard (HCS) to conform to the United Nations’ Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Revision 7 (GHS, Rev. 7).  The proposed modifications include revised criteria for classification of certain health and physical hazards, revised provisions for updating labels, new labeling provisions for small containers, technical amendments related to the contents of safety data sheets (SDSs), and revisions related to definitions and terms used in the standard.  OSHA is seeking comment on the 468-page proposed rule and will accept comments until April 19.

One of the most consequential amendments in the proposed rule is the United States’ recognition of non-flammable aerosols assigned to GHS Aerosols Category 3.  Currently, the U.S. is operating under GHS Revision 3, which does not include provisions for non-flammable aerosols having a heat capacity less than 20 kJ/g.  These substances are currently assigned as Gases Under Pressure and take the cylinder pictogram.

Since OSHA adopted GHS Revision 3 in 2012, the GHS has been updated five times.   The advances put forth by Revisions 4 through 8 to the Globally Harmonized Standard for the Classification and Labeling of Chemicals have created a deepening chasm between the United States and the rest of the world, particularly with respect to the classification and treatment of aerosols.  Adoption of OSHA’s proposed amendments will harmonize the Hazard Communication Standard (HCS) with the international standards currently recognized by many European Union member nations, as well as Australia and Canada.



In the proposed rulemaking, OSHA also noted that GHS Revision 8 contains several significant additional changes in the chapter on aerosols and is requesting comments on whether the agency should adopt two specific changes outlined below:

First, GHS Revision 8 lists classification criteria for aerosols as text in a table rather than referring to the decision logic flowcharts.  When OSHA revised the Hazard Communication Standard in 2012, the agency declined to adopt the GHS decision logic and used its own text for classification of flammable aerosols.  OSHA has determined that there are no substantive differences between OSHA’s current text and the text represented in Table XIV of GHS Revision 8 although they do not contain exactly the same language.

Second, GHS Revision 8 adopted a new hazard category within the aerosols class: Chemicals Under Pressure. These products function similarly to aerosol dispensers (UN1950) but are packed in refillable and non-refillable pressure receptacles up to 450 liters.  Chemicals under pressure present hazards similar to those presented by aerosol dispensers.  Therefore, the classification criteria and hazard information for chemicals under pressure are essentially the same as those for aerosols.  OSHA recognizes that adopting this hazard classification would bring some chemicals that are not currently covered by its regulations into their jurisdiction.

Much More Work to Do

Despite these significant advances, the United States still has a long way to go toward international harmonization.  The U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration, PHMSA, (RSPA’s successor) still maintains its own set of requirements which differ considerably than the harmonized international standards followed by other countries.


Most notably, the international standards define aerosols or aerosol dispensers as non-refillable receptacles made of metal, glass or plastics and containing a gas compressed, liquefied, or dissolved under pressure, with or without a liquid, paste or powder, and fitted with a release device allowing the contents to be ejected as solid or liquid particles in suspension in a gas, as a foam, paste or powder or in a liquid state or in a gaseous state.


However, the United States defines an aerosol (49 CFR §171.8) as “…an article consisting of any non-refillable receptacle containing a gas compressed, liquefied, or dissolved under pressure, the sole purpose of which is to expel a non-poisonous (other than a Division 6.1 Packing Group III material) liquid, paste, or powder and fitted with a self-closing release device allowing the contents to be ejected by the gas.”

Therefore, canned gases and refrigerants (e.g., dusters) are not entitled to reclassification as aerosols because they are gases used to expel themselves.  This difference in classification creates unique challenges for manufacturers and fillers.  Consequently, they are forced to obtain written permission from PHMSA to be able to package these in receptacles intended for aerosols, or ship these as limited quantities because the U.S. requirements currently limit such gases to no more than 120 mL (4 fluid ounces) per inner receptacle.   These permits (which are not recognized by other competent authorities) generally require additional markings on the receptacle including the DOT Special Permit number. 


In cases where aerosols are shipped from the United States to Canada, a DOT Special Permit may only be used to the first point of rest in Canada.  Subsequent movements of these goods must be under the provisions of Canada’s Transport of Dangerous Goods Regulations or under the terms of a Permit for Equivalency of Safety which must be obtained from Transport Canada.


The United States has always maintained a set of requirements that are, generally, more restrictive than the standards imposed by the United Nations’ Recommendations on the Transport of Dangerous Goods Model Regulations (UN Orange Book) or other equivalent instruments.  Why though? 


There is plenty of credible, empirical evidence to suggest that the rules imposed by the UN Orange Book are adequate and will ensure a minimum acceptable level of safety.  Having a different set of rules which is more restrictive, as in the case of the U.S. definition versus international definition of aerosols, or the current GHS classification of non-flammable aerosols, does not promote any greater degree of safety than that which is afforded by a single international standard.  This is particularly true of non-flammable aerosols which pose little risk in transportation to begin with.


Hopefully, the elimination of the ORM-D classification and the adoption of the 7th Revised Edition of the GHS will promote international harmonization without compromising safety.

Steve Hunt is President of ShipMate, Inc., an international recognized dangerous goods consulting firm.  He was a member of the U.S. delegation to the International Maritime Organization’s Carriage of Dangerous Goods Subcommittee and Associate Staff Member of the U.S. Transportation Safety Institute.  He may be reached directly via email at

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