Susan A Korrick Donald Harrington Sally W Thurston Sarah E. Janssen Michael T. Tate YanFen Nong Hua Nong Jihong Liu Chuan Hong Fengxiu Ouyang Sarah E Rothenburg 2024 <p><i>Background</i><span>. Fish and rice are the main dietary sources of methylmercury (MeHg); however, rice does not contain the same beneficial nutrients as fish, and these differences can impact the observed health effects of MeHg. Hence, it is important to validate a biomarker, which can distinguish among dietary MeHg sources.&nbsp;</span><i>Methods</i><span>. Mercury (Hg) stable isotopes were analyzed in hair samples from peripartum mothers in China (</span><i>n</i><span>&nbsp;= 265). Associations between mass dependent fractionation (MDF) (</span><i>δ</i><small>²⁰²</small><span>Hg) and mass independent fractionation (MIF) (</span><i>Δ</i><small>¹⁹⁹</small><span>Hg) (dependent variables) and dietary MeHg intake (independent variable) were investigated using multivariable regression models.&nbsp;</span><i>Results</i><span>. In adjusted models, hair&nbsp;</span><i>Δ</i><small>¹⁹⁹</small><span>Hg was positively correlated with serum omega-3 fatty acids (a biomarker for fish consumption) and negatively correlated with maternal rice MeHg intake, indicating MIF recorded in hair can be used to distinguish MeHg intake predominantly from fish&nbsp;</span><i>versus</i><span>&nbsp;rice. Conversely, in adjusted models, hair&nbsp;</span><i>δ</i><small>²⁰²</small><span>Hg was not correlated with measures of dietary measures of MeHg intake. Instead, hair&nbsp;</span><i>δ</i><small>²⁰²</small><span>Hg was strongly, negatively correlated with hair Hg, which explained 27–29% of the variability in hair&nbsp;</span><i>δ</i><small>²⁰²</small><span>Hg.&nbsp;</span><i>Conclusions</i><span>. Our results indicated that hair&nbsp;</span><i>Δ</i><small>¹⁹⁹</small><span>Hg can be used to distinguish MeHg intake from fish&nbsp;</span><i>versus</i><span>&nbsp;rice. Results also suggested that lighter isotopes were preferentially accumulated in hair, potentially reflecting Hg binding to thiols (</span><i>i.e.</i><span>, cysteine); however, more research is needed to elucidate this hypothesis. Broader impacts include 1) validation of a non-invasive biomarker to distinguish MeHg intake from rice&nbsp;</span><i>versus</i><span>&nbsp;fish, and 2) the potential to use Hg isotopes to investigate Hg binding in tissues.</span></p> application/pdf 10.1039/D4EM00231H en Royal Society of Chemistry Hair mercury isotopes, a noninvasive biomarker for dietary methylmercury exposure and biological uptake article