Scientists at the University of New Mexico identified at least six pollutants, primarily arsenic, nitrates, uranium and lead, linked to neurological and developmental problems. Fracking fluids and PFAS were also detected in the drinking water that also flows to the homes of about 320 million Americans. The six contaminants represent a small fraction of the thousands of chemical agents present in drinking water, the authors report. The team also warned that two or more contaminants could be present in a water source, 'presenting the possibility of synergistic effects,' the researchers said.