Reasonable package guidance

Q: I need clarification on regulatory requirements for net content of packaging goods. How is weight loss considered when evaluating whether the fill weight meets a label claim?

The National Institute of Standards and Technology (NIST) Handbook 133 (NIST, 2016) allows for some loss due to "ordinary and customary exposure to conditions that normally occur in good distribution practice" and defines those allowances for products such as flour, pet food or pasta. For products not listed there, the handbook states: "Inspectors should follow their jurisdiction’s guidance for making their determination on an acceptable moisture allowance." This may be clear enough for an inspector within his or her jurisdiction, but it’s vague for a producer that supplies to different regions.

Other international regulations show a similar lack of precision in the requirement. For example, the International Organization of Legal Metrology (OIML) Recommendations 87—Quantity of Product in Prepackages (OIML, 2004) states: "Legal metrology officials may permit reasonable deviations in the quantity of product (that is, hygroscopic products) caused by ordinary and customary exposure to environmental conditions that occur in storage and distribution." At no point, however, does it quantify what is meant by "reasonable."

I also couldn’t find any reference to timing. Is it acceptable if the content meets the label claim at the time it leaves the factory? How is the evaluation made six months, one year or even two years later?

To comply with the regulations while avoiding unnecessary overfilling costs, these requirements and evaluation processes must be clearly understood. No one I asked was able to answer these questions. My organization operates globally, and I would appreciate it if you could extend your comments to other international requirements.

Carlos Liberatori
Brantford, Ontario

A: Defining what is "reasonable" is one of the most complex technical issues we deal with when providing technical advice to weights and measures officials and packers on moisture-loss allowances. The 1977 Supreme Court decision on Jones v. Rath (430 U.S. 519) ruled that federal packaging laws preempted state laws or regulations that did not recognize allowances for reasonable moisture loss or gain in packaged goods.

Prior to that case, most states enforced what were sometimes called "net weight at time of sale" requirements. Today, "reasonable" variations for moisture loss are found in state and federal laws, which govern the net-weight requirements for packaged commodities.

These laws allow for reasonable variations from the net quantity of contents when they are caused by two factors:

  • Variations caused by the packaging process and machinery, which occur if the packer is following current good manufacturing practice.
  • Variations caused by the loss or gain of moisture from the package, which occur if the packer follows current good distribution practices.

The second requirement helps prevent product tampering or mishandling after it leaves a packer’s plant, such as instances in which delivery workers were caught removing product from packages to illegally sell it on the side. There also are poor distribution practices, such as transporting perishable foods in unrefrigerated trucks, which frequently accelerates moisture loss beyond a packer’s expectations.

After weights and measures inspectors find a sample of packages containing less than the quantity represented on the label, they usually contact the packer to determine:

  • Whether the variations are due to the packing process.
  • Whether the packer is following good manufacturing practices. For example, an inspector would ensure scales or filling machines are calibrated and measurement standards are traceable to NIST, and there are statistical process controls in place and supervision to ensure that under-filled packages are reprocessed or removed from sale.

After the variations are understood or eliminated as the primary cause for the shortages, a packer also can provide information on the product and packaging, and present moisture-loss studies conducted on the product. The term "reasonable" is used in law because the amount of moisture loss that may occur, even if a packer is following current good manufacturing and distribution practices, will vary due to a number of factors, including: the product, packaging material, humidity levels, temperature, airflow around the package, other handling and storage practices, and shelf life (time).

For these and other reasons, weights and measures officials typically define what is "reasonable" on a case-by-case basis after consulting with a packer and reviewing production data, moisture-loss studies or by conducting a limited moisture-loss study under controlled conditions to validate a packer’s claims. Because weights and measures inspections are law enforcement functions of each state, their inspectors and attorneys general or states’ attorneys who prosecute these cases follow criminal procedures to ensure due process is provided. As in any criminal prosecution, it is ultimately a court of law that decides whether the moisture allowance is "reasonable."

The moisture allowances currently in NIST Handbook 133, "Checking the Net Content of Packaged Goods," for pasta, dry pet food and flour were developed and adopted only after years of studies and negotiations and should not be interpreted to mean that packages of those products do not lose more than 3% of their weight due to moisture loss. The studies supporting these negotiated moisture allowances typically revealed much larger losses among packages of these products in some marketplaces around the country.

Developing a single value for the entire nation, however, required regulators and packers to compromise on these negotiated values. Flour was adopted in the 1980s, and it has worked effectively to help both parties provide good consumer protection and fair competition in the marketplace.

Note that if an official has sufficient evidence to suspect a packer is taking advantage of one of the moisture allowances in NIST Handbook 133, the official can take legal action against the packer in spite of the 3% moisture allowance. Likewise, if a packer believes the 3% moisture allowance in NIST Handbook 133 is not "reasonable," the packer also is not prohibited from challenging the action in an administrative hearing or courtroom.

Defining reasonable moisture allowances is a challenge for weights and measures officials and packers around the world. For more than 25 years, while serving as the U.S. representative to OIML Technical Committee 6, which is responsible for OIML Recommendation 87—Quantity of Product in Prepackage, I can affirm that officials and packers from every country face these same questions and challenges about what is a "reasonable" moisture loss.

Kenneth S. Butcher
Program leader
Laws and Metric Program

National Institute of
Standards and Technology,
Office of Weights and Measures
Gaithersburg, MD

Additional resources

For a formal explanation of package requirements and moisture loss, read section 1.2 "Package Requirements" in chapter one of the National Institute of Standards and Technology (NIST) Handbook 133, "Checking the Net Contents of Packaged Goods" (NIST, 2016), at http://tinyurl.com/nist-hb-133.

For information on how the moisture allowances were developed, read section 2.5.6 (p. 247) of NIST Handbook 130, "Uniform Laws and Regulations in the Areas of Legal Metrology and Engine Fuel Quality" (NIST, 2016), at http://tinyurl.com/nist-hb-130.

For examples of some of the good manufacturing practices that weights and measures inspectors look for in packaging facilities, read NIST Handbook 130, sections 2.6.11 "Good Quantity Control Practices," and 2.6.12 "Point-of-Pack Inspection Guidelines" at http://tinyurl.com/nist-hb-130.

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