Mass trends of parabens, triclocarban and triclosan in Arizona wastewater collected after the 2017 FDA ban on antimicrobials and during the COVID-19 pandemic

Antimicrobials like parabens, triclosan (TCS), and triclocarban (TCC) are of public health concern worldwide due to their endocrine-disrupting properties and ability to promote antimicrobial drug resistance in human patho-gens. The overall use of antimicrobials presumably has increased during the COVID-19 pandemic, whereas TCS and TCC may have experienced reductions in use due to their recent ban from thousands of over-the-counter (OTC) personal care products by the U.S. Food and Drug Administration (FDA). No quantitative data are available on the use of parabens or the impact the FDA ban had on TCC and TCS. Here, we use wastewater samples (n = 1514) from 10 different communities in Arizona to measure the presence of the six different antimicrobial products (TCS, TCC, and four alkylated parabens [methylparaben (MePb), ethylparaben (EtPb), propylparaben (PrPb), butylparaben (BuPb)]) collected before and during the COVID-19 pandemic using a combination of solid-phase extraction, liquid chromatography/tandem mass spectrometry (LC-MS/MS), and isotope dilution for absolute quantitation. The average mass loadings of all antimicrobials combined (1,431 +/- 22 mg/day per 1,000 people) after the onset of the local epidemic (March 2020 -October 2020) were signifi-cantly higher (945 +/- 62 mg/day per 1,000 people; p < 0.05) than before the pandemic (January 2019 -February 2020). Overall, parabens (EPbs = 999 +/- 16 mg/day per 1,000 people) were the most used antimicrobials, followed by TCS (117 +/- 14 mg/day per 1,000 people) and TCC (117 +/- 14 mg/day per 1,000 people). After the 2017 U.S. FDA ban, we found a statistically significant (p < 0.05) reduction in the mass loadings of TCS (-89%) and TCC (-80%) but a rise in paraben use (+72%). Mass flows of 3 of a total of 4 parabens (MePb, EtPb, and PrPb) in wastewater were significantly higher upon the onset of the epidemic locally (p < 0.05). This is the first longitudinal study investigating the use of antimicrobials during the COVID-19 pandemic by employing wastewater-based epidemiology. Whereas an overall increase in the use of antimicrobials was evident from analyzing Arizona wastewater, a notable reduction in the use of TCS and TCC was evident during the pandemic, triggered by the U.S. FDA ban.