Ecotoxicology and Environmental Safety

Mitochondrial ploidy -- the relative copy number of mitochondrial DNA per mitochondrion -- may serve as an early marker of cellular stress and a potential signal of genotoxic damage. In this study, we investigate the dynamics of mitochondrial ploidy in iPSC cells in vitro following exposure to a range of chemical mutagens. Using a qPCR-based method allowing accurate quantification of mitochondrial DNA and mitochondria number, we reveal distinct changes in mitochondrial ploidy that correlate with the genotoxic impact of specific agents. Among the mutagens tested, MX, benzidine, cyclophosphamide, hydrogen peroxide, semustine and nickel (II) chloride induced the most pronounced alterations in mitochondrial DNA content and organization. These findings suggest that mitochondrial ploidy can be used as a sensitive molecular indicator of mutagenic stress, potentially reflecting mitochondrial genome maintenance and organelle adaptation mechanisms.

Polychlorinated biphenyls (PCBs) are ubiquitous and representative pollutants that pose great health risks. While cells responses to dioxin-like PCBs tend to be studied on a bulk scale, few studies have been made from a single-cell level. Here, by using single-cell RNA sequencing, we depicted a detailed landscape of hepatic nonparenchymal cells intricate responses to PCB126 exposure. A total of 13 clusters were identified. Notably, PCB126 exposure resulted in cell-type-specific gene expression profiles and genetic pathways. By analyzing genes related to aryl hydrocarbon receptors, we discovered that PCB126 induced the canonical genomic AhR pathway mainly in endothelial cells. In contrast, other cell types showed little induction. Enrichment pathway analysis indicated that immune cells changed their transcriptional patterns in response to PCB126. ScRNA-seq is a powerful tool to dissect underlying mechanisms of chemical toxicity regarding biological heterogeneity. Taken together, our study not only extends our current understanding of PCB126 toxicity, but also emphasizes the importance of in vivo cell heterogeneity in environmental toxicology.

Exposure to chemical pollutants can alter the rate, and genome-wide distribution of germline mutations. However, studies measuring the effect of chemical exposure on mutation rate and spectra have not considered the ecological and evolutionary backgrounds of studied genotypes, which could influence the rates and patterns of germline mutations in altered environments, e.g., chemical pollution. Utilizing a study of natural Daphnia pulex populations, we conducted a comprehensive experiment to test our hypothesis that adaptation to chemical pollution also protects the germline from mutagenesis. We, 1) identified Daphnia pulex populations that have adapted to live in mining-devastated regions by increasing their cadmium tolerance. 2) We completed a mutation-accumulation (MA) experiment with an adapted genotype to measure the germline mutation rate in both control conditions and an environmentally relevant cadmium concentration. 3) We compared these MA experiment results to a previously reported, identically designed MA experiment with a nonadapted genotype. We report that patterns of cadmium-induced mutagenesis in the adapted genotype were reversed compared to our previous observations in the nonadapted genotype. Cadmium exposure altered the single nucleotide mutation (SNM) rate in the same genome regions in adapted and nonadapted genotypes, but the rates were changed in opposite directions. Cadmium also altered specific SNM classes in these genotypes in opposite directions. The reversal of mutational trends in the adapted genotype suggests protection against cadmium genotoxicity. We further demonstrate that adapted populations have elevated gene copy-number and expression levels of metallothionein, the protein that protects against cadmium toxicity by binding to cadmium irreversibly.

Over 100,000 people were exposed to arsenic-contaminated drinking water in Antofagasta, Chile from 1958-1970. Individuals born during this high exposure period have elevated rates of cancer, lung and cardiovascular disease, and hypertension. However, the mechanisms of long-term arsenic toxicity remain unclear. We investigated whether early-life arsenic exposure was associated with altered glucocorticoid levels in adulthood. This study included 114 individuals born in Antofagasta during the high exposure period and 118 individuals born elsewhere. Arsenic exposure metrics were constructed based on residential histories and included: concentration at birth, peak and highest 5-year average between ages 0-10 years, and highest lifetime 5-year average, and lifetime cumulative exposure. Morning plasma cortisol concentrations were measured using a cell-based bioassay. Individuals in the highest quartile of highest lifetime 5-year average of arsenic exposure had approximately 11% lower mean log cortisol levels than those in the lowest quartile of exposure ({beta} = -0.116; 95% CI: -0.229, -0.003). In sex-stratified analyses, associations were stronger among females. For example, females in the highest quartile of cumulative exposure had 22.0% lower cortisol levels compared to those in the lowest quartile ({beta} = -0.248; 95% CI: -0.444, -0.053) and the test for interaction by sex was statistically significant (p = 0.036). This study is the first to show that early-life arsenic exposure may have lasting effects on cortisol. These findings highlight endocrine disruption as a mechanism contributing to long-term health effects of early arsenic exposure.

In vitro toxicology has used immortalized cancer cell lines as model human systems for decades. However, these cell lines pose problems in designing toxicity testing programs as they inherently do not represent normal human biology. There is also a huge number of such cell lines to choose from, derived from human cancer cells from nearly every tissue. We explored the idea of using available basal gene expression data (NCI-60 cell line panel and Human GTEx tissue data) to determine if there was sufficient variability in cell line gene expression to group cell lines by relevance to specific human tissues. The transcriptomic analysis suggests that the variability in gene expression in cancer cell lines and in normal human tissue is minimal. The overall basal gene expression of cancer cells lines even overlapped normal human tissue gene expression. While some human tissues (e.g., lung) have basal expression profiles that do not appear to be like any cancer cell line, including cancers that may be derived from the same tissue, most human tissues show basal expression profiles comparable to several cancer cell lines. These results are important to address the genomic baseline and variability of cancer cell lines used for new approach methods of toxicity testing.

There are substantial gaps in our empirical knowledge of the effects of chemical exposure on aquatic life that are unlikely to be filled by traditional laboratory toxicity testing alone. One possible alternative of generating new toxicity data is cross-species extrapolation (CSE), a statistical approach in which existing data are used to predict the effect of a chemical on untested species. Some CSE models use relatedness as a predictor of chemical sensitivity, but relatively little is known about how strongly shared evolutionary history influences sensitivity across all chemicals. To address this question, we conducted a survey of phylogenetic signal in the toxicity data from aquatic animal species for a large set of chemicals using a phylogeny inferred from taxonomy. Strong phylogenetic signal was present in just six of thirty-two toxicity datasets, and there were no clear shared properties among those datasets with strong signal. Strong signal was rare even among chemicals specifically developed to target insects, meaning that these chemicals may be equally lethal to non-target taxa, including chordates. When signal was strong, distinct patterns of sensitivity were evident in the data, which may be informative when assembling toxicity datasets for regulatory use. Although strong signal does not appear to manifest in aquatic toxicity data for most chemicals, we encourage additional phylogenetic evaluations of toxicity data in order to guide the selection of CSE tools and as a means to explore the patterns of chemical sensitivity across the broad diversity of life.

Chronic contaminant exposure may impose hidden physiological costs long before obvious demographic or health effects become detectable in wildlife populations. Epigenetic clocks quantify biological ageing and may provide sensitive biomarkers of cumulative toxicological stress. Per-and polyfluoroalkyl substances (PFAS) are persistent contaminants that bioaccumulate in marine food webs, yet their long-term physiological consequences for wildlife remain poorly understood. Here, we tested whether PFAS exposure is associated with accelerated biological ageing in common dolphins (Delphinus delphis). We analysed liver PFAS concentrations and skin DNA methylation profiles from 30 stranded or bycaught dolphins from New Zealand waters. Epigenetic age was estimated using a recently developed species-specific epigenetic clock, and age acceleration was calculated as the residual deviation between epigenetic and chronological age. Using an information-theoretic modelling framework, we assessed the effects of total PFAS burden, sex, and their interactions on epigenetic age acceleration. Total PFAS concentrations were positively associated with epigenetic age acceleration, indicating that dolphins with higher PFAS burdens were biologically older than expected for their chronological age. Each 1 ng g{square}{superscript 1} increase in total PFAS was associated with an average increase of 0.031 years in biological age. Sex did not significantly influence age acceleration, suggesting that PFAS-associated ageing effects occur across both sexes. Although modest, this effect is consistent with PFAS acting as a chronic physiological stressor influencing molecular ageing processes. Our findings provide the first evidence linking PFAS exposure to accelerated biological ageing in a wild mammal, highlighting epigenetic ageing as an integrative biomarker of long-term contaminant effects in wildlife.

We measured baseline levels of 19 trace element and mercury speciation for grey seals (Halichoerus grypus) from the Gulf of St. Lawrence (GSL), Quebec, Canada. With interest growing in commercializing grey seal products for human consumption in this region, the goal of this study was to measure essential and non-essential trace elements in grey seals to evaluate health concerns and nutritional benefits. From 2015 to 2019, 120 grey seals were sampled by hunters and researchers at 4 sites in the GSL. Muscle, liver, heart and kidney samples were analyzed for 10 non-essential elements (Sb, As, Be, B, Cd, Pb, Hg, Ni, Tl, Sn) and 9 essential elements (Co, Cr, Cu, Fe, Mg, Mn, Mo, Se, Zn). Both total mercury (THg) and methylmercury (MeHg) were analysed for a subset of samples. Many elements were undetected in liver (Sb, As, Be, B, Cr, Co, Pb, Ni, Tl, Sn) and muscle tissues (same, plus Cd, Mn, Mo). Results showed lower element concentrations in the muscle (Fe, Mg, Se) and livers (Cd, Cr, Hg, Mn, Mo, Se) of young-of-the-year harvested in the winter (< 6 weeks old) compared to older animals feeding at sea. For older seals ([~] 5 months to 29 years), we did not observe progressive age-dependent bioaccumulation. Sex-specific differences were not very pronounced, but a few elements were 30 - 70% higher in the muscle (THg, MeHg) and liver (Mn, Zn) of male seals. Comparison to Canadian dietary reference intakes shows that a weekly portion of liver from young-of-the-year (< 6 weeks old) is a good source of essential elements (Cu, Fe) and that muscle and liver from this age category does not exceed reference values for toxic elements (As, Cd, Pb, MeHg). Ongoing discussions with regional public health professionals will help to develop dietary recommendations for the consumption of older grey seals. HIGHLIGHTSO_LIWe measured baseline levels of 19 trace elements in grey seals harvested from the Gulf of St. Lawrence. C_LIO_LIWe evaluated nutritional benefits and health concerns of human consumption of grey seal products. C_LIO_LIOnce seals began feeding at sea ([~] 5 mo), many element concentrations increased, but did not bioaccumulate progressively with age afterwards. C_LIO_LISome elements were more concentrated in the muscle (mercury) and livers (manganese, zinc) of male seals. C_LIO_LIYoung seal (< 6 we) livers are a good dietary sources of copper and iron, while its muscle and liver were below reference values for toxic elements. C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/458200v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@ad9ea6org.highwire.dtl.DTLVardef@8adf1borg.highwire.dtl.DTLVardef@13d992eorg.highwire.dtl.DTLVardef@113c8c7_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioRxiv has withdrawn this preprint because we no longer have confidence on the validity of the manuscript and the identity of the authors. Therefore, this work should not be cited as a reference for this project.

Microplastics (MP) are ubiquitous environmental contaminants with diverse physicochemical characteristics. Many studies have shown that size, shape, and polymer type are responsible for their toxicity, but this also seems to differ among MP from the same plastic type. One parameter likely contributing to these differences is plastic chemicals, a broad class of compounds intentionally or unintentionally added to plastics during their production and manufacturing. However, knowledge on the composition of plastic chemicals and their effects remains scarce. Therefore, to elucidate the chemical aspect of MP toxicity, we exposed Daphnia magna individuals to MP (PET, PBS, and PDLLA), cellulose, extracted particles (eMP), and methanol-based extracts of these particles for 10 days. Chemicals within such extracts were analyzed via GC-MS. This study was conducted with reduced food availability to investigate plastic effects in an environmentally relevant scenario. The introduction of a high-food control suggests that a more realistic feeding regime might exacerbate the plastic effects of the selected treatments. Our results indicated that, depending on the polymer type, plastic chemicals determine MP toxicity, which varies according to the endpoint investigated (i.e., body length, reproduction, levels of ROS and LPO). Body length, in particular, was significantly impaired by PET and PDLLA extracts, whereas reproduction was affected by most treatments. The investigated biochemical parameters (ROS and LPO) were not affected by the exposure. These results suggest that MP toxicity strongly depends on their chemical composition, whereas adverse effects due to physical properties are present independently of chemical composition across all MP types. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/724551v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@3c2d4forg.highwire.dtl.DTLVardef@c2ccd7org.highwire.dtl.DTLVardef@116721dorg.highwire.dtl.DTLVardef@9df888_HPS_FORMAT_FIGEXP M_FIG C_FIG

Quantitative Adverse Outcome Pathways (qAOPs) may support next-generation risk assessment by integrating New Approach Methodologies (NAMs) for derivation of points of departure. To be useful, a qAOP should be chemical-agnostic. However, existing qAOP studies often pool multi-chemical data without adequately addressing inter-chemical heterogeneity. Consequently, fundamental pathway relationships become obscured by heterogeneity-induced noise, thereby compromising the reliability of chemical-agnostic predictions. We developed a chemical-agnostic calibration approach to addresses this challenge by leveraging hierarchical structures to systematically separate chemical-specific heterogeneity from underlying pathway effects. Through this methodological framework, chemical-specific deviations are explicitly modeled as random effects, enabling the extraction of pathway-level parameters that represent core mechanistic relationships independent of individual chemical properties. Through simulation studies across varying heterogeneity levels, we demonstrate that performance differences between models with and without hierarchical calibration reveal the magnitude of heterogeneity in the data. Moreover, when heterogeneity is substantial, an uncalibrated qAOP should not be considered truly chemical-agnostic in practice, as it confounds pathway-level effects with chemical-specific variation. We demonstrated the application of this calibration approach through a case study of non-mutagenic liver tumor. The framework proposed in this study enhances qAOP generalizability while preserving the chemical-agnostic principle, supporting robust NAMs-based next-generation risk assessments. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/642550v2_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@e7011eorg.highwire.dtl.DTLVardef@1fa7be9org.highwire.dtl.DTLVardef@1dd0b52org.highwire.dtl.DTLVardef@1123a93_HPS_FORMAT_FIGEXP M_FIG Figure 1: For TOC only C_FIG

This analysis examines the relationship between pesticide usage and cancer incidence rates in the Midwest United States using a Bayesian regression model. Pesticide usage data from 1992-2002 and cancer incidence rates from 2017-2022 were analyzed alongside demographic factors such as smoking, binge drinking, and obesity. After selecting the best-fitting distribution, we evaluated the effects of pesticide exposure on cancer rates. The results showed no confident effects from Glyphosate. Atrazine usage results seem to be unreliable, thus no clear conclusion can be made. However, we found Ethalfluralin, 2,4-D, Malathion, and MCPA use was associated with higher overall rates. These findings highlight the need for further research into the potential health risks of pesticide exposure and its role in cancer development.

High metabolic rate may provide fitness benefits for individuals. But high metabolic rates incur energetic costs and the need to ingest more food, increasing the risks of ingesting harmful substances from the environment. How organisms respond to elevated levels of ionizing radiation is an important question in the light of increasing pollution from nuclear accidents and waste, as well as ever-increasing reliance on radiation in medical diagnostics and therapies. We investigated how limits to metabolic rate, and aerobic metabolic scope (ceiling of energetic activity above maintenance levels), of wild rodents inhabiting a gradient of radioactive contamination from the Chernobyl accident covary with the biological burden of radionuclides in their bodies. Our results demonstrate that high biological dose rate correlates with high self-maintenance and low aerobic capacity in adults. In contrast, in subadults high dose rate correlates with high aerobic capacity. Consequently, high dose rate correlates with low aerobic scope in adults, but with high aerobic scope in subadults. Despite the uncertainty of the causal mechanisms, whether the dose rate affects the metabolic rate, the reverse or the reciprocal feedback prevail, it can be hypothesized that metabolic down-regulation could contribute to protection against radioactive exposure. Yet, metabolic down-regulation might be constrained by developmental obligations. Understanding the physiological mechanisms affecting responses to radiation exposure is key for risk assessment of environmental contamination, radiotherapies, and space exploration, and may help to rectify discordant opinions concerning the effects of radiation on the ecology of organisms living in Chornobyl.

Pollution is a significant threat to aquatic ecosystems globally and, in order to survive, natural populations depend upon their ability to rapidly develop tolerance to chemical stressors. We examined whether early-life priming enhances life-long copper-tolerance in a model fish species via developmental plasticity. Stickleback (Gasterosteus aculeatus) embryos were pre-exposed to a low concentration of copper (10 {micro}g/L) during early development, reared in clean water for nine months alongside a control group, and then exposed to copper (0,10 and 20 {micro}g/L) for 96 h as adults. Priming markedly reduced evidence of copper-toxicity in adult gills at the transcriptional level (including reduced cellular stress response (CSR) and disruption of ion-homeostasis) and increased inducibility of the metal-binding protein, metallothionein. In parallel, we identified epigenetic and microbiome-mediated mechanisms likely contributing to this tolerance. Pre-exposure induced persistent DNA methylation changes, consistent with priming of CSR and ion-homeostasis pathways. We identified enhanced copper-tolerance in the gill microbiota of primed fish that likely also contributed to host tolerance. These findings provide critical evidence for developmental plasticity induced by chemical stressors in animals, highlight the importance of integrated microbiome and epigenetic responses, and enhance our understanding of how natural populations cope with pollution in their environment.

Previously, we have demonstrated that certain ferric salts common in Archean waters, such as iron trichloride and ferric ammonium citrate, can protect liposomes from destruction by short-wavelength UVC light. In this study, we investigate the propagation of 254 nm UV radiation through aqueous FeCl3 solutions and its interactions with liposomes. We then consider these findings in the context of early Earth UV environment, discuss their implications for our hypothesis of the Darwinian evolution of liposomes, and integrate them with our previous experimental results.

MotivationThe Adverse Outcome Pathways (AOP) framework advances alternative toxicology by prioritizing the mechanisms underlying toxic effects. It organizes existing knowledge in a structured way, tracing the progression from the initial perturbation of a molecular event--caused by various stressors--through key events (KEs) across different biological levels, ultimately leading to adverse outcomes that affect human health and ecosystems. However, the increasing volume of toxicological data presents a significant challenge for integrating all available knowledge effectively. ResultsArtificial intelligence provides powerful methods to analyze and integrate large, heterogeneous data sources. Within this framework, the AOP-helpFinder text mining tool, accessible as a web server, was designed to identify stressor-event and event-event relationships by automatically screening scientific literature in the PubMed database, facilitating the development of AOPs. The proposed new version introduces enhanced functionality by incorporating additional data sources, automatically annotating events from the literature with toxicological database information in a systems biology context. Users can now visualize results as interactive networks directly on the web server. With these advancements, AOP-helpFinder 3.0 offers a robust solution for integrative and predictive toxicology, as demonstrated in a case study exploring toxicological mechanisms associated with radon exposure. AvailabilityAOP-helpFinder is available at https://aop-helpfinder-v3.u-paris-sciences.fr/ Contactkarine.audouze@u-paris.fr Supplementary informationSupplementary data are available on Zenodo (https://zenodo.org/records/15193936) and codes on GitHub (https://github.com/systox1124/AOP-helpFinder).

BackgroundAlthough population blood lead levels (BLLs) have fallen dramatically since the removal of leaded gasoline and paint, lead remains an important environmental and occupational toxicant. Indoor firing ranges uniquely combine confined airspaces, repeated detonations, and lead based ammunition conditions that result in persistent exposure for millions of users. ObjectivesTo quantify adult cardiovascular, renal, and cognitive health impacts associated with lead exposure from indoor firing ranges in the United States using the most recent dose-response relationships from the United States Environmental Protection Agency (EPA) Integrated Science Assessment (ISA) for Lead (2024) and recent epidemiologic evidence. MethodsBlood lead data from Laidlaw et al. (2017) and 2017-2025 citations were synthesized with NHANES 2015-2022 data (Day, Braun & Hoover 2025). Dose-response coefficients came from EPA ISA (2024) and the Summary Table--Adult BLL Dose-response Relationships. Health outcomes were modeled for adults using an estimated 16,000-18,000 indoor ranges serving 2-3 million users annually. ResultsAverage BLLs among users (4-12 {micro}g/dL) exceeded the United States Centers for Disease Control (CDC) reference value of 5 {micro}g/dL. Modeled effects included a 5-8 mm Hg rise in systolic blood pressure, 20,000-40,000 additional hypertension cases, and 1,000-3,000 extra myocardial infarctions each year. Renal function declined 3-6 mL min-{superscript 1} 1.73 m-{superscript 2} and cognitive scores fell 0.2-0.3 SD among heavily exposed groups. ConclusionsMost indoor ranges operate at BLLs above thresholds for cardiovascular and renal harm. Transition to lead-free ammunition and modern ventilation could prevent thousands of hypertension and cardiac events annually.

BackgroundAir pollution has been recognized as an untraditional risk factor for myocardial infarction (MI). However, the MI risk attributable to long-term exposure to fine particulate matter (PM2.5) is unclear, especially in younger populations, and few studies represented the general population. MethodsWe applied the difference-in-differences approach to estimate the relationship between annual PM2.5 exposure and hospitalizations for MI among U.S. residents and further identified potential susceptible subpopulations. All hospital admissions for MI in ten U.S. states over the period 2002-2016 were obtained from the Healthcare Cost and Utilization Project State Inpatient Database. ResultsIn total, 1,914,684 MI hospital admissions from 8,106 ZIP codes in ten states from 2002 to 2016 were included in this study. We observed a 1.35% (95% CI: 1.11-1.59%) increase in MI hospitalization rate for 1 g/m3 increase in annual PM2.5 exposure. The estimate was robust to adjustment for surface pressure, relative humidity and co-pollutants. In the population with exposure at or below 12 g/m3, there was a larger increment of 2.17% (95% CI: 1.79-2.56%) in hospitalization rate associated with 1 g/m3 increase in PM2.5. Young people (0-34 years) and elderly people ([&ge;]75 years) were the two most susceptible age groups. Residents living in more densely populated or poorer areas and individuals with comorbidities were observed to be at a greater risk. ConclusionsThis study indicates long-term residential exposure to PM2.5 could lead to increased risk of MI among U.S. general population. The association persists below current standards. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LILong-term exposure to PM2.5 increased the risk of myocardial infarction in the general U.S. population. C_LIO_LIYoung individuals aged 0-34 years had the highest relative risk from long-term exposure to PM2.5, and elderly people aged [&ge;]75 years were the second most susceptible to the effects. C_LIO_LIIndividuals with iron deficiency anemia, psychosis, and renal failure were more susceptible to the long-term effects of PM2.5 on MI. C_LI What are the clinical implications?O_LILong-term PM2.5 exposure is one of the important modifiable environmental risk factors for myocardial infarction, therefore, air pollution control and behavioral interventions should be taken to prevent the occurrence of myocardial infarction. C_LI

Lead (Pb), chromium (Cr), and cadmium (Cd) are heavy metals that contaminate sites throughout North America. Historically, toxicological effects of Pb, Cr, or Cd compounds have been investigated in a hybrid mouse strain, B6C3F1. However, humans have more genetic diversity and population variability in response to toxicants than is represented in this homogeneous mouse model, which leaves genetic effects on dose response uncertain. Use of the Collaborative Cross (CC) addresses the problem of limited genetic diversity inherent in models like B6C3F1. In previous work, blood Pb levels in panel of female CC lines exposed to high-dose (0.1%) lead acetate showed a strain dependent response. Four strains from the original study with varying Pb blood levels after exposure were selected to determine if strain and sex dependence was exhibited in a two-week acute exposure to Pb, but also to Cr or Cd exposure. To investigate genetic background influence on metal deposition, five animals of each sex from each strain were placed on an American diet for one week prior to dosing high- (0.1%) or low- (0.01%) dose Pb acetate, high- (0.1%) or low- (0.01%) sodium dichromate, or high- (0.1%) or low- (0.01%) cadmium chloride via drinking water ad libitum for 14-days, matching the standard short-term exposure of the National Toxicology Program. Body composition was measured before the start of dosing and prior to necropsy using EcoMRI. Blood Pb at necropsy from this study suggests the strain dependent trends observed in previous exposures is conserved for acute Pb exposure but with different trends for Cr and Cd indicating that even a small panel of strains will not suffice for estimating variation across all toxicants.

In this study, we assessed the issue of coal particles absorbing extracellular proteins and tested the effects of different culture conditions and processing strategies to address this issue. Our data show that there is no effective strategy to solve this problem. We agree with previous reports that cytokine binding experiments should be performed to implement appropriate correction factors in order to calculate the accurate production of secreted cytokines in the supernatant of cell culture experiments. This is an underappreciated issue in many published studies on the comparative potency of particles from different sources.