Micro-distribution of arsenic in toenail clippings using laser ablation inductively coupled plasma mass spectrometry: implications for biomonitoring.

Toenails are a common monitoring tool for arsenic exposure, but the risk of external contamination of toenails has cast doubt on its usefulness. The main objective of this study is to investigate the micro-distribution of arsenic through the dorsoventral plane of nail clippings to understand endogenous vs exogenous sources. We used laser-ablation inductively coupled plasma mass spectrometry to measure arsenic through a dorsoventral cross-section of the nail plate collected from reference (N = 17) and exposed individuals (N = 35). Our main results showed (1) bulk toenail concentrations measured using ICP-MS in this study ranged from 0.54 to 4.35 µg/g; (2) there was a double-hump pattern in arsenic concentrations, i.e., dorsal and ventral layers had higher arsenic than the inner layer; (3) the double-hump was more pronounced in the exposed group (ventral: 6.25 µg/g; inner: 0.75 µg/g; dorsal: 0.95 µg/g) than the reference group (ventral: 0.58 µg/g; inner: 0.15 µg/g; dorsal: 0.29 µg/g) on average; (4) the distribution was, in part, associated with different binding affinity of nail layers (i.e., ventral > dorsal > inner); (5) most individuals in the higher exposure group showed > 25% contamination in ventral and dorsal nail layers; and (6) there were no statistically significant correlations between LA-ICP-MS arsenic with either bulk toenail arsenic or urine arsenic from the same individuals. Our results on micro-distribution and binding affinity provide insight into the impact of external contamination on arsenic concentrations and show how LA-ICP-MS can access the protected inner nail layer to provide a more accurate result.

Exploring practices, challenges, and priorities for human health and ecological risk assessments in Indigenous communities in Canada.

Indigenous peoples in Canada are disproportionately exposed to environmental contaminants and may face elevated health risks related to their unique cultural, spiritual, and economic relationships with the land, including the use of traditional food systems. However, to date, institutionalized approaches to assess risks to human and ecological health from contaminants have not been well developed or implemented with Indigenous community contexts in mind. There is regulatory interest in developing new approach methods for risk assessment, and thus an opportunity to increase their relevance to Indigenous communities in which they will be ultimately applied. Therefore, we conducted an anonymous mixed-methods survey of those involved with risk assessment in Indigenous communities in Canada to: (1) understand risk assessment practice in Indigenous communities, (2) explore challenges with conventional assessment methods and compare these across sectors, and (3) gather perspectives on the development of new approaches. In all, 38 completed survey responses were received (14% response rate). Respondents were from Indigenous community environment and health offices (21% of respondents), Indigenous governments (8%), federal and provincial governments (21%), and academia (45%). Risk communication was seen as the most challenging part of risk assessment (71% responded "difficult"), and nearly all respondents agreed that time (86%), cost (76%), and resource availability (86%) were "moderate" to "serious" problems. Few respondents (16%) had heard of "new approach methods" for risk assessment, and 76% of respondents (and 100% of community-based respondents) agreed on the need to develop improved risk assessment approaches. To modernize risk assessment, respondents recommended advancing cumulative risk assessment methods, improving risk communication, and promoting Indigenous leadership and Traditional Knowledge in assessment activities. Integr Environ Assess Manag 2024;20:1677-1692. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Reduction of Glyoxalase 1 Expression Links Fetal Methylmercury Exposure to Autism Spectrum Disorder Pathogenesis.

Glyoxalase 1 (Glo1) is an essential enzyme to detoxify methylglyoxal (MGO), a cytotoxic byproduct of glycolysis. Accumulating studies have shown an important role of Glo1 in regulating cortical development and neurogenesis, potentially contributing to the pathogenesis of autism spectrum disorder (ASD) when impaired. We have previously shown that prenatal exposure to non-apoptotic low-dose methylmercury (MeHg), an environmental pollutant, induces premature cortical neurogenesis and ASD-like behaviors in a rodent model. In this study, we aimed to determine the underlying molecular mechanisms that mediate prenatal MeHg-induced premature neuronal differentiation and abnormal neurodevelopment. Using single-cell RNA sequencing (scRNA-seq) and real-time quantitative PCR (RT-qPCR), we found that prenatal MeHg exposure at a non-apoptotic dose significantly reduced Glo1 gene expression in embryonic cultured radial glia precursors (RGPs). In cultured RGPs, the knockdown of Glo1 expression increased neuronal production at the expense of the cultured RGPs population, while overexpression of Glo1 restored MeHg-induced neuronal differentiation back to normal levels. Furthermore, we found that co-treatment with both MeHg and multiple MGO scavengers or a CREB inhibitor (iCREB) mitigated MeHg-induced premature neuronal differentiation, reinforcing the role of Glo1 and CREB in mediating MeHg-induced neuronal differentiation. Our findings demonstrate a direct link between MeHg exposure and expression of an ASD risk gene Glo1 in cortical development, supporting the important role of gene-environment interaction in contributing to the etiology of neural developmental disorders, such as ASD.

Omega-3 world map: 2024 update.

In 2016, the first worldwide n3 PUFA status map was published using the Omega-3 Index (O3I) as standard biomarker. The O3I is defined as the percentage of EPA + DHA in red blood cell (RBC) membrane FAs. The purpose of the present study was to update the 2016 map with new data. In order to be included, studies had to report O3I and/or blood EPA + DHA levels in metrics convertible into an estimated O3I, in samples drawn after 1999. To convert the non-RBC-based EPA + DHA metrics into RBC we used newly developed equations. Baseline data from clinical trials and observational studies were acceptable. A literature search identified 328 studies meeting inclusion criteria encompassing 342,864 subjects from 48 countries/regions. Weighted mean country O3I levels were categorized into very low ≤4%, low >4-6%, moderate >6-8%, and desirable >8%. We found that the O3I in most countries was low to very low. Notable differences between the current and 2016 map were 1) USA, Canada, Italy, Turkey, UK, Ireland and Greece (moving from the very low to low category); 2) France, Spain and New Zealand (low to moderate); and 3) Finland and Iceland (moderate to desirable). Countries such as Iran, Egypt, and India exhibited particularly poor O3I levels.