Lab Matters Fall 2023 | Page 40

APHL 2023 POSTER ABSTRACTS

AGRICULTURAL , VETERINARY AND ENVIRONMENTAL TESTING TECHNOLOGIES AND PRACTICES

Anatoxin-a and Saxitoxin : Cyanotoxins of Increasing Frequency in Pennsylvania Freshwater Bloom Events

P . Higgins 1 , A . Mickey 1 , C . Sterling 2 ; 1 Pennsylvania Department of Environmental Protection , 2 Pennsylvania Department of Environmental Protection Bureau of Laboratories

The main harmful algal bloom ( HAB ) season in Pennsylvania ( PA ) typically lasts from May to October , and HAB events have been occurring in greater abundance and duration due to climate change . HAB events involving certain types of cyanobacteria can lead to the presence of different cyanotoxins in recreational waters . Anatoxin-a and saxitoxin are neurotoxins that are more potent in detrimental health effects than the other two common cyanotoxins of concern ( microcystin and cylindrospermopsin ). Many state and the federal recreational guidance documents only provide values related to the presence of microcystin and cylindrospermopsin and there is little consideration for the potential health effects when multiple toxin-producing cyanobacteria types are present in a single bloom event . During the 2022 HAB season in PA , anatoxin-a and saxitoxin were detected more frequently than in previous HAB seasons and multiple types of cyanobacteria that could produce two or more cyanotoxins were observed in individual HAB events . The prevalence of anatoxin-a and saxitoxin detection during HAB events , including multiple cyanotoxin events , suggests a need for additional focus on anatoxin-a , saxitoxin , and multiple cyanotoxin events in surveillance programs for freshwater bodies .

Presenter : Pamela Higgins , pahiggins @ pa . gov

Comparing Methods Utilized to Test for PFAS in Aqueous Samples : EPA 537.1 , EPA 533 , ISO 21675

E . Walters ; Biotage

Extraction protocols and analytical methods utilized for detecting per- and polyfluoroalkyl substances ( PFAS ) in aqueous samples have evolved rapidly over the past decade . Since the US Environmental Protection Agency ( EPA ) released method 537 in 2009 , laboratories across the world have made significant progress in their ability to quantify these contaminants . From 2013 – 2015 , EPA 537 was utilized for assessment monitoring as part of the Unregulated Contaminant Monitoring Rule ( UCMR ) 3 program and was updated to EPA method 537.1 , shortly thereafter . In late 2019 , EPA method 533 and International Organization for Standardization ( ISO ) Method 21675 were released , which in addition to EPA method 537.1 , enable laboratories to quantify up to 37 PFAS analytes with exceptional precision and accuracy . In anticipation of the upcoming UCMR 5 program , it is beneficial to review these top methods utilized for evaluating PFAS in aqueous samples . This study focuses on comparing the extraction protocols and analytical requirements for each method . Results from these methods will be compared to assess method robustness , analyte detection limits , data accuracy and reproducibility . This evaluation demonstrates the value that can be obtained from comparing protocols and analytical results from current methodology to make informed decisions about the future of PFAS monitoring .

Presenter : Evan Walters , evan . walters @ biotage . com

ddPCR on Beach Water in San Diego County

S . Hallis , B . Costa , W . Jordan , J . Corrigan , W . Wooten ; County of San Diego Health & Human Services Agency

Droplet digital polymerase chain reaction ( ddPCR ) was used for the detection of fecal indicator bacteria ( FIB ), Enterococcus spp ., in San Diego County beach water samples collected as part of regulatory monitoring activities starting on May 5 , 2022 . The ddPCR method was approved by EPA for use only in San Diego County for the purpose of beach monitoring and notification . CDPH approved the County of San Diego ’ s use of the ddPCR method at 1413 DNA copy number / 100 mL threshold . Additionally , the County of San Diego Public Health Laboratory received approval from ELAP to add the alternative test procedure to the FOA certificate . ddPCR results are typically turned around within 10 hours compared to culture techniques which produce results in 24 hours . The faster turnaround time is more protective of public health as beaches can be posted earlier when numbers are in exceedance of the beach action threshold . Additionally , the beaches can be opened sooner as results can be provided the same day . Furthermore , PCR based water monitoring techniques are more sensitive than previously used culture techniques . Sampling of south county sites occurs daily , and other sites are sampled per AB-411 guidelines . At beaches in the south county , the community is disproportionately impacted by cross border sewage flows from Mexico and the Tijuana River Valley . Beach threshold exceedances have an impact on tourism dollars for the affected communities . South swell conditions were prominent during the spring and summer months resulting in many exceedances in south county . South swells may push sewage along the San Diego coastline . Peak tourism season generally runs between Memorial Day and Labor Day . This time period is the focus of data analyzed for this poster . In 2022 , south county sites were in exceedance 60.2 % of peak tourism season compared to 17.0 % in non-south county sites . Imperial beach pier was in exceedance for 77.9 % of peak tourism season in 2022 compared to 0 % in 2021 ( prior to ddPCR implementation ); whereas Torrey Pines was in exceedance for 12.5 % in 2022 compared to 0 % in 2021 . Imperial Beach Pier exceedances were observed with south swell conditions 44.6 % of the time . Swell events appear to bring an influx of enterococcus which may persist for several days . In the absence of a swell event , copy number / 100 mL decreases over time due to mixing and degradation . The impact of south swell on ddPCR results may indicate that Mexico serves as a point source of sewage leading to lengthy beach advisories for south county . Lastly , implementing this new test which is more sensitive and provides more accurate testing than previous methods , creates unique opportunities to manage the new data . One such creative solution initiated in San Diego is the creation of the warning tier to allow for proper public notification so that beach visitors can make an informed decision before entering the potentially impacted water .

Presenter : Samantha Hallis , samantha . hallis @ sdcounty . ca . gov