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4 2 0 1 7 W A T E R Q U A L I T Y R E P O R T 1 PA R T P E R T R I L L I O N UNREGULATED SYNTHETIC OR NATURALLY OCCURRING CHEMICALS THAT ARE NOT COMMONLY MONITORED BY WATER UTILITIES ARE KNOWN AS CONTAMINANTS OF EMERGING CONCERN. More than 100,000 chemicals are registered in the United States, and new chemicals and microorganisms continue to be identified. Some of these contaminants can be detected at extremely low levels (parts per trillion – ppt) by continuously improving test methods. For reference, one ppt is approximately the equivalent of one grain of sugar in an Olympic-sized swimming pool. The health significance of these trace contaminants is often under review and the subject of further study and research. An example category of a contaminant of emerging concern is per and polyfluoroalkyl substances (together PFASs). PFASs are a class of man-made chemicals used for common product applications, such as waterproof and stainproof fabrics, nonstick cookware, some food packaging materials and fire suppression foams. PFASs can enter lakes, rivers or groundwater through industrial releases, discharges from wastewater treatment plants and the use of fire-fighting foam. The fact that a substance is detectable doesn't mean that it is immediately harmful. The EPA issues a health advisory for contaminants of emerging concern when research indicates a potential health impact. Health advisories provide information to the public so state and local agencies can take appropriate action to protect public health. In 2017, the Town of Cary tested for 14 PFASs on four different occasions. Five PFASs were detected at very low levels in Cary's water. Of those chemicals, only Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS) have an EPA health advisory of 70 ppt. In our water, the combined concentration of PFOA and PFOS ranged from 3.9 ppt to 13.6 ppt. The Town of Cary is committed to providing high-quality, safe drinking water and is closely following the science. We are actively investigating innovative treatment technologies to further reduce contaminants of emerging concern from our drinking water. EMERGING CONTAMINANTS EMERGING CONTAMINANTS IN OUR DRINKING WATER SUBSTANCE (UNIT OF MEASURE) YEAR SAMPLED AVERAGE AMOUNT DETECTED RANGE LOW – HIGH VIOLATION TYPICAL SOURCE Perfluorobutanesulfonic acid (PFBS) (ppt) 2017 3.1 2.3 – 3.6 No Man-made chemicals used for waterproof and stain proof fabrics, nonstick cookware, some food packaging materials and fire suppression foams. Perfluoroheptanoic acid (PFHpA) (ppt) 2017 13 9 – 16 No Perfluorohexanoic acid (PFHxA) (ppt) 2017 26 20 – 30 No Perfluorooctanoic acid (PFOA) (ppt) 2017 3.6 3.1 – 4 No Perfluorooctane sulfonate (PFOS) (ppt) 2017 6.9 3.9 – 9.6 No For more information about emerging contaminants, see Town of Cary's website: http://bit.ly/EmergingContaminants

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