By Rick Andrew

In September 2021, in this column, I described an initiative of the NSF Joint Committee on Drinking Water Treatment Units to develop requirements and a testing protocol for POU and POE devices for the reduction of microplastics in drinking water. The column summarized the work of a task group to first define the term microplastics, especially the size of the plastic particles falling under consideration as microplastics.

The task group reviewed available information such as academic research and other studies regarding microplastic contamination in water, analyzed the information and arrived at definition of microplastics as particles of plastic having a size in the range of 1 µm to 5,000 µm. Based on this definition, the task group concluded that the NSF/ANSI 42 nominal particulate Class I reduction claim could serve as an appropriate measure for effectiveness in reduction of microplastics, because the test for this claim requires a test particle size range from 0-80 µm, with the reduction claim based specifically on reduction of only the 0.5µm- to 1µm-sized particles present in the challenge.

The test also evaluates the ability of the system to effectively filter particles when it is new and no filter cake has built up, as well as when the system has become significantly caked and the filter is clogged, even as the flow is rapidly cycled on after a rest period and the seals in the filter system are stressed. Essentially, the task group concluded, based on the relative size range of the particles involved and the rigorous nature of the test protocol itself, filtration systems capable of meeting the requirements for nominal particulate reduction, Class I would effectively reduce the plastic particles defined as microplastics.

The task group then took this conclusion and developed language to modify NSF/ANSI 401 to refer to NSF/ANSI 42 for the testing method and requirement, with the microplastics reduction claim itself being added to NSF/ANSI 401. The selection of NSF/ANSI 401 instead of NSF/ANSI 42 to house the microplastics reduction claim is because of the current status of microplastics as an emerging compound or incidental contaminant, consistent with the scope of NSF/ANSI 401 NSF/ANSI 42, which on the other hand, addresses claims of treatment of aesthetic contaminants that may impact the taste, odor or appearance of the water. Microplastics are not visible and have no taste or odor, thus making NSF/ANSI 401 the clear choice as the standard to include the microplastics reduction claim.

Status update
At the time the column was written, a ballot prepared by the task group was out for consideration and voting by the Joint Committee. Since then, the voting period has ended with 100-percent affirmative votes cast. Based on that successful result, the proposal was then brought to the NSF Council of Public Health Consultants for ultimate ratification as a last step before being adopted into NSF/ANSI 401. The NSF Council of Public Health Consultants has also completed their review and voting period, and has approved the proposal

Next steps
An updated version of NSF/ANSI 401, which will include these requirements for claims of microplastic reduction, was scheduled to be published in December. With publishing of the updated standard, the microplastics reduction claim becomes official and becomes available for conformity assessment, including third-party certifications. Manufacturers with products that are currently third-party certified for nominal particulate reduction, Class I, can leverage this new microplastics reduction claim by liaising with their certification body and taking the necessary steps to fully conform with the requirements. These steps will include updating product documentation and literature (including potentially the packaging); performance data sheet; replacement element packaging; installation, operation and maintenance instructions, and system data plate. With these updates, the certification listings can also be updated to reflect the claim of microplastics reduction under NSF/ANSI 401.

The steps are similar for manufacturers with products that currently do not have claims of nominal particulate reduction, class I claims, except that these products will additionally have to be tested to assure that they conform to the testing requirement. The testing requirement is that a challenge of particles is introduced into test systems and the systems must reduce the number of particles in the size range of ≥ 0.5 µm to < 1 µm by 85 percent when operated, according to the specifications in the test protocol. Details of this testing protocol were included in the September, 2021 Water Matters column.

Benefits to stakeholders
The way that the addition of this new microplastics reduction claim requirement in NSF/ANSI 401 was accomplished, by basing the claim on an already existing test for nominal particulate reduction, Class I, brings significant benefits to stakeholders of the POU/POE industry. Manufacturers with products already meeting the requirements for nominal particulate reduction, Class I, can quickly and inexpensively establish a claim of microplastics reduction without the need for any additional product research and development or laboratory testing.

End users of POU/POE systems who have concerns about potential microplastic contamination of drinking water will soon have multiple options for products with third party-certified microplastics reduction claims. Regulatory officials can rest assured that these reduction claims are valid, based on robust standards developed through a consensus process, with conservative test methods that ensure product performance according to claims.

The NSF Joint Committee on Drinking Water Treatment Units (and the task group working on the microplastics reduction issue) used a scientifically based yet pragmatic approach when working on this initiative. Through a logical analysis of the issue of microplastics contamination, coupled with an assessment of the existing nominal particulate reduction, Class I test method and requirements, they were able to arrive at a sound solution without reinventing the wheel or adding unnecessary costs to testing and certification, thus benefiting manufacturers, end users, and regulators.

About the author
Rick Andrew is NSF’s Director of Global Business Development – Water Systems. Previously, he served as General Manager of NSF’s Drinking Water Treatment Units (POU/POE), ERS (Protocols) and Biosafety Cabinetry Programs. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email: Andrew@nsf.org

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