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ObjectivesAnimal bioassays have demonstrated convincing evidence of the potential carcinogenicity to humans of titanium dioxide (TiO2), but limitations in cohort studies have been identified, among which is the healthy worker survivor effect (HWSE). We aimed to address this bias in a pooled study of four cohorts of TiO2workers.MethodsWe reanalysed data on respirable TiO2dust exposure and lung cancer mortality among 7341 male workers employed in TiO2production in Finland, France, UK and Italy using the parametric g-formula, considering three hypothetical interventions: setting annual exposures at 2.4 (U.S. occupational exposure limit), 0.3 (German limit) and 0 mg/m3for 25 and 35 years.ResultsThe HWSE was evidenced. Taking this into account, we observed a positive association between lagged cumulative exposure to TiO2and lung cancer mortality. The estimated number of lung cancer deaths at each age group decreased across increasingly stringent intervention levels. At age 70 years, the estimated number of lung cancer deaths expected in the cohort after 35-year exposure was 293 for exposure set at 2.4 mg/m3, 235 for exposure set at 0.3 mg/m3, and 211 for exposure set at 0 mg/m3.ConclusionThis analysis shows that HWSE can hide an exposure–response relationship. It also shows that TiO2epidemiological data could demonstrate an exposure–effects relationship if analysed appropriately. More epidemiological studies and similar reanalyses of existing cohort studies are warranted to corroborate the human carcinogenicity of TiO2. This human evidence, when combined with the animal evidence, strengthens the overall evidence of carcinogenicity of TiO2.

L’Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail (Anses) a été saisie pour établir une liste hiérarchisée de procédés de travail à expertiser en vue d’une éventuelle inclusion à l’arrêté français fixant notamment la liste des procédés cancérogènes dans le Code du travail.

We address here the importance of epidemiological evidence in risk assessment and decision-making in Europe. To illustrate this, titanium dioxide (TiO2) was used as a model compound. TiO2is widely used as an odorless white pigment and opacifying agent. A recent systematic review assessing the weight of evidence on the relationship between exposure to TiO2(all forms) and cancer in humans questions the assumptions that TiO2is an inert material of low toxicity. Based on this new data, France submitted a proposal to classify TiO2as a possible human carcinogen under the European regulation. The European Chemicals Agency Risk assessment committee concluded that TiO2(all forms) warrants a classification as a suspected human carcinogen via inhalation (Category-2) under the CLP regulation (for Classification, Labeling and Packaging of chemicals). No considerations was given to TiO2particle size, which may affect human health effects. Consequently, further epidemiological studies are needed to assess possible associations between different physical–chemical characteristics of TiO2exposures and their impact on human health. This would allow strengthening the evidence on which to build the most appropriate regulation and to guaranty safe use given any exposure route of any TiO2particle shape or size.

Embryonic exposure through maternally transferred pollutants can affect embryo vitality, survival, and health. Reptiles face global declines and are sensitive to embryonic pollutant exposure. Yet, they are often neglected in pollution risk assessment and conservation. We analyzed maternal transfer of organic pollutants in reptiles through a systematic extraction, homogenization, and integration of published data on organic pollutants measured in mother–egg pairs into a comprehensive database (DOI:10.5281/zenodo.10900226), complemented with molecular physical–chemical properties of the pollutants. Over four decades, 17 publications provided 19,955 data points shifting from legacy to emerging contaminants although research on newer contaminants lags regulatory and societal demands. Challenges including taxonomic bias, heterogeneity in sampled tissues, and 73% of censored data complicate comparative analyses. However, significant opportunities were identified including the use of the turtle Malachlemys terrapinand snake Enhydris chinensisas flagship species where a large amount of data is available across tissues (allowing investigation into physiological relations) and compounds (allowing insights into maternal transfer across the chemical universe). Data on other freshwater and marine turtles provide the possibility of exploring taxonomic patterns in this subgroup. The analysis, integrated database, and discussion present opportunities for research in an era where science needs to achieve more with limited wildlife data.

The aim of this work is to study the effects of different individual behaviours on the overall growth of a spatially distributed population. The population can grow on two spatial patches, a source and a sink, that are connected by migrations. Two time scales are involved in the dynamics, a fast one corresponding to migrations and a slow one associated with the local growth on each patch. Different scenarios of densitydependent migration are proposed and their effects on the population growth are investigated. A general discussion on the use of aggregation methods for the study of integration of different ecological levels is proposed.

Our aim is to model the Salmo trutta population dynamics (three age-classes) in an arborescent river network (four levels, 15 patches), by considering both migrations (fast time scale) and demography (slow time scale). We study how the environmental management can influence the global population dynamics. We present a general model coupling both a linear discrete model for constant migrations and a non-linear density-dependent Leslie model for the demography, with (15 × 3) difference equations (15 patches, three age-classes). The variable aggregation method applied to discrete time models allows us to aggregate the previous model into a new one with only three equations. We assume fecundity and survival gradients with respect to the river network levels. The Salmo trutta whole population tends towards an equilibrium state depending on the environmental structure, and we show that dams have a stronger influence than channelling on this equilibrium.

Several lines of evidence such as the basal location of thermophilic lineages in large-scale phylogenetic trees and the ancestral sequence reconstruction of single enzymes or large protein concatenations support the conclusion that the ancestors of the bacterial and archaeal domains were thermophilic organisms which were adapted to hot environments during the early stages of the Earth. A parsimonious reasoning would therefore suggest that the last universal common ancestor (LUCA) was also thermophilic. Various authors have used branch-wise non-homogeneous evolutionary models that better capture the variation of molecular compositions among lineages to accurately reconstruct the ancestral G + C contents of ribosomal RNAs and the ancestral amino acid composition of highly conserved proteins. They confirmed the thermophilic nature of the ancestors of Bacteria and Archaea but concluded that LUCA, their last common ancestor, was a mesophilic organism having a moderate optimal growth temperature. In this letter, we investigate the unknown nature of the phylogenetic signal that informs ancestral sequence reconstruction to support this non-parsimonious scenario. We find that rate variation across sites of molecular sequences provides information at different time scales by recording the oldest adaptation to temperature in slow-evolving regions and subsequent adaptations in fast-evolving ones.

Various mathematical models have been used to explore the dynamics of transposable elements (TEs) within their host genomes. However, numerous factors can influence their dynamics, and we know only little about the dynamics of TEs when they first began to invade populations. In addition, the influence of population structuring has only recently been investigated. Transposable Element Simulator Dynamics, a population genomics simulation environment, has therefore been developed to provide a simple tool for analyzing the dynamics of TEs in a community based on (i) various TE parameters, such as the transposition and excision rates, the recombination rate and the coefficient of selection against TE insertions; and (ii) population parameters, such as population size and migration rates. The simulations can be used to illustrate the dynamic fate of TEs in structured populations, can be extended by using more specific molecular or demographic models, and can be useful for teaching population genetics and genomics. Availability: TESD is distributed under GPL from the Pôle Bioinformatique Lyonnais (PBIL) web server at http://pbil.univ-lyon1.fr/software/TESD Contact: biemont@biomserv.univ-lyon1.fr