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UCMR 5 - is your lab ready?

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Every five years, as part of its responsibilities under the Safe Drinking Water ACT (SDWA), the EPA uses the Unregulated Contaminant Monitoring Rule (UCMR) program to collect data for contaminants that are suspected to be present in drinking water but do not have health-based standards set under the Safe Drinking Water Act. The UCMR program provides the EPA with scientifically valid data on the occurrence of these contaminants in drinking water, which allows the EPA to determine whether the population is being exposed, and how high the levels of exposure might be. 


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UCMR data sets are one of the primary sources of occurrence and exposure information the EPA uses to develop regulatory decisions for emerging contaminants. Since 2001, the UCMR has operated on approximately a five-year cycle, monitoring no more than 30 contaminants in each cycle. On Feb. 22, EPA Acting Administrator Jane Nishida signed the proposed fifth Unregulated Contaminant Monitoring Rule (UCMR 5). 


Of the 30 contaminants listed in the fifth UCMR, 29 are per- or poly-fluoroalkyl substances, otherwise known as PFAS. The impact of these ‘forever chemicals’ on the environment and human health is well-documented. More than 4700 PFAS compounds exist, according to the National Institute of Environmental Health Sciences (NIEHS), and after decades of use and little to no deterioration, many of these are accumulating in our surroundings – and bodies – to an alarming extent. Studies have shown PFAS to be present in the blood of 97% of the US population, and given their persistence and multiple potential routes into the body, bioaccumulation is a particular concern.  


Research conducted to date reveals many possible links between human exposure to PFAS and adverse health effects, including metabolic changes, reduced fertility, reduced immune function, liver and kidney damage, and reduced foetal growth. In animal studies PFAS have also been shown to be carcinogenic, and links have been drawn to increased rates of certain human cancers in specific high-PFAS areas. 


PFAS featured in UCMR 5 include perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). These compounds were amongst the first PFAS to be identified as being hazardous. PFOA and PFOS are now no longer made in the USA, although they are still made in some other countries and could potentially reach US consumers in certain types of products. The full 29 PFAS listed in the UCMR 5 proposal are outlined in the chart below. 


11-chloroeicosafluoro-3-oxaundecane-1- sulfonic acid (11Cl-PF3OUdS)

perfluoro-4-methoxybutanoic acid (PFMBA)

perfluorooctanesulfonic acid (PFOS)

1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)

perfluorobutanesulfonic acid (PFBS)

perfluorooctanoic acid (PFOA)

1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)

perfluorobutanoic acid (PFBA)

perfluoropentanesulfonic acid (PFPeS)

1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)

perfluorodecanoic acid (PFDA)

perfluoropentanoic acid (PFPeA)

4,8-dioxa-3H-perfluorononanoic acid (ADONA)

perfluorododecanoic acid (PFDoA)

perfluoroundecanoic acid (PFUnA)

9-chlorohexadecafluoro-3-oxanone-1- sulfonic acid (9Cl-PF3ONS)

perfluoroheptanesulfonic acid (PFHpS)

n-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)

hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX)

perfluoroheptanoic acid (PFHpA)

n-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)

nonafluoro-3,6-dioxaheptanoic acid (NFDHA)

perfluorohexanesulfonic acid (PFHxS)

perfluorotetradecanoic acid (PFTA)

perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)

perfluorohexanoic acid (PFHxA)

perfluorotridecanoic acid (PFTrDA)

perfluoro-3-methoxypropanoic acid (PFMPA)

perfluorononanoic acid (PFNA)



The only non-PFAS compound included in the fifth UCMR is lithium, which was detected in 56% of treated drinking water samples from 25 PWSs at a median concentration of 10.8 µg/L. Curiously, lithium in drinking water has been associated by multiple studies with reduced rates of suicide, homicide, and rape, a correlation which may have something to do with its use as a treatment for bipolar illness. Lithium can, however, also be toxic to humans. The question of whether lithium contamination in United States drinking water represents a significant threat is an open one, which the EPA is seeking to answer by including it in the fifth UCMR. 


Neither lithium nor the 29 PFAS listed in UCMR 5 are subject to national primary drinking water regulations. The monitoring would not be required immediately but instead would occur between 2023 and 2025. The EPA states that the rule is meant to provide the agency, states and communities “with scientifically valid data on the national occurrence of these contaminants in drinking water,” and “would provide new data that is critically needed to improve EPA’s understanding of the frequency” that these PFAS are found in drinking water. 


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How to Take Part 


Laboratories seeking to participate in UCMR 5 must be approved by the EPA, which is currently accepting expressions of interest for early applications. This requires a simple six-step process:


  1. Request to participate

Laboratories wanting to join the UCMR 5 Laboratory Approval Program must email the EPA to request registration materials.


  1. Registration

This provides the EPA with necessary information to ensure each laboratory receives a customised application package, with the final deadline August 1, 2022.


  1. Application package

Laboratory applicants will complete and return the customised application package outlining a range of data and information regarding analytical equipment.


  1. Review of application package

The EPA will review application packages and, if necessary, request follow-up information.


  1. Proficiency testing

Successful applicants will receive a PT sample containing an analyte or mixture of analytes known to the EPA, but unknown to the laboratory. The laboratory must meet specific acceptance criteria for the analysis of each analyte in each method for which the laboratory is seeking approval.


  1. Written EPA approval

After successful completion of other steps, the EPA sends the laboratory a notification letter listing the methods for which approval is either “pending”, or for which approval is “granted”. 


How we can help 


Approved laboratories must adhere to the quality assurance and quality control procedures and criteria outlined in the method and rule language to maintain their approval status. Once a laboratory is disapproved, there is no opportunity for reinstatement during the UCMR 5 monitoring period. It is therefore crucial that laboratories are able to maintain and demonstrate their analytical excellence throughout the program. 


LGC is committed to supporting laboratories involved in UCMR 5. Our Dr. Ehrenstorfer reference materials have been used by laboratories participating in previous UCMR programs to ensure accurate, reliable results, thereby producing high-quality data and allowing the EPA to make sound regulatory decisions. The majority of our range is accredited to ISO 17034, the gold standard for reference material providers (RMPs) around the world. 


Take a look at our comprehensive portfolio of quality reference materials, which includes an extensive selection of PFAS compounds in many formats, or get in touch to find out how we can be of assistance. 


We will also be continually updating and publishing new articles with additional information and insight as the UCMR 5 process progresses, so check back regularly for further guidance!

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