NJIT finds an ultra-short-chain PFAS in 64 of 70 New Jersey tap-water samples

The headline percentages rest on small counts. Sixty-four of 70 tap samples is 91.4 percent and 34 of 43 beverages is 79.1 percent [d1, d2], which matches the reported figures ^[2]. But 70 tap samples spread over 21 counties is about 3.3 per county ^[17], so "every county" means each county had at least one detection among a few samples ^[7]. Six tap samples had no detectable TFA ^[18], and the median of 352 nanograms per liter describes only the 64 that did ^[8]. The summary does not describe how the tap sites were chosen or say whether any of these concentrations carries a health risk.

The beverage comparison has the same limit. The 12 formulated beverages averaged about 52 times the TFA of the 31 bottled waters ^[9]. An average over 12 products can be moved by a few high readings. The top reading was 94,100 nanograms per liter, about 69 times the 1,360 found in the highest tap sample [c10, d5].

Researchers have not determined why some formulated beverages ran so high ^[11]. Siwei Gu, the lead author, said ingredients or manufacturing processes may be contributing ^[13], then limited that idea: "However, we did not analyze individual ingredients or investigate the manufacturing processes, so we cannot definitively identify the sources of TFA in these products," Gu said ^[12].

The monitoring gap has a physical cause. PFOA and PFOS have drawn regulatory attention from the U.S. Environmental Protection Agency, while ultra-short-chain PFAS have largely escaped routine testing because their size and chemistry make them hard to detect with established methods ^[4]. "It is much smaller in molecular size, highly soluble in water and does not bind strongly to many filter materials that work well for capturing traditional PFAS," Gu said ^[5]. The team needed a specialized laboratory method to screen for five such compounds ^[6]. The researchers describe the work as the first statewide U.S. monitoring study of ultra-short-chain PFAS ^[1], published in Environmental Science & Technology Letters ^[3].

Arjun Venkatesan, who directs NJIT's Emerging Contaminants Research Laboratory, said the team expected TFA in drinking water because European studies had reported it widely, but "what surprised us was how frequently it was detected" ^[14].

In our view the tap result is sturdier than the beverage result. A detection rate that high is hard to dismiss even in 70 samples, and it came from a method built for the compound. Twelve beverages cannot describe a product category, and the study did not test what is in them. About three samples per county cannot describe the level at one town's tap ^[17].