Intra-population variation of hair and fingernail stable hydrogen, oxygen, carbon and nitrogen isotopes in London, Ontario, Canada residents during the COVID-19 pandemic

Sawyer C E Rowe, The University of Western Ontario

Abstract

Lockdowns and travel restrictions during the COVID-19 pandemic forced a significant fraction of London, Ontario, Canada residents to remain in one location for long enough to reach isotopic equilibrium with their primary drinking water source(s). This situation created ideal natural conditions for measuring the isotopic fractionation between the stable hydrogen and oxygen isotopes of drinking water and hair or nail tissues, and for determining the magnitude of intra-population variation in tissue δ²H and δ¹⁸O. Hair and nail of participants who reported exclusively drinking London municipal tap water spanned much larger δ²H and δ¹⁸O ranges than their drinking water. Forensic δ²H_{drinking water} and δ¹⁸O_{drinking water} reconstructions presuming a constant tissue-drinking water isotopic fractionation therefore carry high uncertainty. London and southern Ontario values of δ¹³C_hair and δ¹⁵N_hair for omnivores vary by < 1 ‰ between COVID-19 and pre-COVID-19 times, suggesting that the overall dietary habits of Londoners were not affected by the pandemic.