A new human hair certified reference material for total mercury, methylmercury, and trace element analyses

Mercury (Hg) release into the environment poses significant health risks due to its presence in air, land, and water systems. In aquatic ecosystems, inorganic Hg is converted to toxic methyl Hg (MeHg), leading to bioaccumulation within fish. Human exposure to Hg, primarily through contaminated fish and seafood, poses significant health risks. Monitoring Hg levels in human hair is a valuable and noninvasive method for assessing individual exposure. Hair provides a stable, long-term record of organomercury concentrations and dietary intake, making it useful for large-scale population studies. Accurate determination of MeHg levels is critical for assessing dietary exposure. The increasing global demand for reliable data on Hg exposure highlights the need for readily available and well-characterized certified reference materials (CRMs) for THg and MeHg analyses.

The National Institute for Environmental Studies (NIES) has developed and certified a new human hair reference material, NIES CRM No. 13-a, to enhance the accuracy and comprehensiveness of mercury (Hg) exposure assessments. This CRM provides certified values for total Hg (THg) and methylmercury (MeHg), reference values for an expanded suite of trace elements, and informational values for stable Hg isotope ratios. Rigorous preparation, homogenization, stability testing (short- and long-term), and an interlaboratory collaborative study following ISO Guide 35 ensured its reliability, with a recommended minimum sample size of 20 mg for Hg analyses (50 mg for certain trace elements).

Key characteristics:

• NIES CRM No. 13-a certifies THg (1.06 ± 0.07 mg/kg) and MeHg (0.858 ± 0.075 mg/kg) on a dry-weight basis.
• Reference values include As, Cd, Pb, Se, Zn, and expanded elements (e.g., Sb, Ba, Mn).
• Includes δ²⁰²Hg and mass-independent fractionation information values for Hg isotope tracing.
• Demonstrated excellent homogeneity (u_hom < 1%) and stability (–30 to +50 °C short term; stable for at least 10 years).
• Certified through multi-method analyses (CVAAS, GC-ECD, ICP-MS, MC-ICP-MS) and interlaboratory validation.

This comprehensive CRM represents a significant advancement in quality control for biomonitoring and environmental health studies of mercury and trace elements in human hair.

Akane Yamakawa, Kimiyo Nagano, Kaoru Onishi, Miyuki Ukachi, Teruyo Ieda, Miyako Kobayashi, Tomoharu Sano, Miyuki Iwai-Shimada, Kenta Iwai, Kozue Inamasu, David Amouroux, Emmanuel Tessier, Milena Horvat, Adna Alilović, Polona Klemenčič, Ermira Begu, Marta Jagodic Hudobivnik, Rand Matthew, Koichi Haraguchi, Ping Li, Pablo Rodríguez-González, Laura Suárez-Criado, Ligang Hu, Nozomi Takeda, Yu-Feng Li, Keisuke Uchida, Human hair certified reference material for total mercury, methylmercury, and trace element analyses, Accred. Qual. Assur., 30 (2025) 277-290. DOI: 10.1007/s00769-025-01637-x

last time modified: October 11, 2025