Health-motivated taxes on red and processed meat: A modelling study on optimal tax levels and associated health impacts.

BACKGROUND: The consumption of red and processed meat has been associated with increased mortality from chronic diseases, and as a result, it has been classified by the World Health Organization as carcinogenic (processed meat) and probably carcinogenic (red meat) to humans. One policy response is to regulate red and processed meat consumption similar to other carcinogens and foods of public health concerns. Here we describe a market-based approach of taxing red and processed meat according to its health impacts. METHODS: We calculated economically optimal tax levels for 149 world regions that would account for (internalize) the health costs associated with ill-health from red and processed meat consumption, and we used a coupled modelling framework to estimate the impacts of optimal taxation on consumption, health costs, and non-communicable disease mortality. Health impacts were estimated using a global comparative risk assessment framework, and economic responses were estimated using international data on health costs, prices, and price elasticities. FINDINGS: The health-related costs to society attributable to red and processed meat consumption in 2020 amounted to USD 285 billion (sensitivity intervals based on epidemiological uncertainty (SI), 93-431), three quarters of which were due to processed meat consumption. Under optimal taxation, prices for processed meat increased by 25% on average, ranging from 1% in low-income countries to over 100% in high-income countries, and prices for red meat increased by 4%, ranging from 0.2% to over 20%. Consumption of processed meat decreased by 16% on average, ranging from 1% to 25%, whilst red meat consumption remained stable as substitution for processed meat compensated price-related reductions. The number of deaths attributable to red and processed meat consumption decreased by 9% (222,000; SI, 38,000-357,000), and attributable health costs decreased by 14% (USD 41 billion; SI, 10-57) globally, in each case with greatest reductions in high and middle-income countries. INTERPRETATION: Including the social health cost of red and processed meat consumption in the price of red and processed meat could lead to significant health and environmental benefits, in particular in high and middle-income countries. The optimal tax levels estimated in this study are context-specific and can complement the simple rules of thumb currently used for setting health-motivated tax levels.

A restatement of the natural science evidence base concerning the health effects of low-level ionizing radiation.

Exposure to ionizing radiation is ubiquitous, and it is well established that moderate and high doses cause ill-health and can be lethal. The health effects of low doses or low dose-rates of ionizing radiation are not so clear. This paper describes a project which sets out to summarize, as a restatement, the natural science evidence base concerning the human health effects of exposure to low-level ionizing radiation. A novel feature, compared to other reviews, is that a series of statements are listed and categorized according to the nature and strength of the evidence that underpins them. The purpose of this restatement is to provide a concise entrée into this vibrant field, pointing the interested reader deeper into the literature when more detail is needed. It is not our purpose to reach conclusions on whether the legal limits on radiation exposures are too high, too low or just right. Our aim is to provide an introduction so that non-specialist individuals in this area (be they policy-makers, disputers of policy, health professionals or students) have a straightforward place to start. The summary restatement of the evidence and an extensively annotated bibliography are provided as appendices in the electronic supplementary material.

Species-Level Para- and Polyphyly in DNA Barcode Gene Trees: Strong Operational Bias in European Lepidoptera.

The proliferation of DNA data is revolutionizing all fields of systematic research. DNA barcode sequences, now available for millions of specimens and several hundred thousand species, are increasingly used in algorithmic species delimitations. This is complicated by occasional incongruences between species and gene genealogies, as indicated by situations where conspecific individuals do not form a monophyletic cluster in a gene tree. In two previous reviews, non-monophyly has been reported as being common in mitochondrial DNA gene trees. We developed a novel web service "Monophylizer" to detect non-monophyly in phylogenetic trees and used it to ascertain the incidence of species non-monophyly in COI (a.k.a. cox1) barcode sequence data from 4977 species and 41,583 specimens of European Lepidoptera, the largest data set of DNA barcodes analyzed from this regard. Particular attention was paid to accurate species identification to ensure data integrity. We investigated the effects of tree-building method, sampling effort, and other methodological issues, all of which can influence estimates of non-monophyly. We found a 12% incidence of non-monophyly, a value significantly lower than that observed in previous studies. Neighbor joining (NJ) and maximum likelihood (ML) methods yielded almost equal numbers of non-monophyletic species, but 24.1% of these cases of non-monophyly were only found by one of these methods. Non-monophyletic species tend to show either low genetic distances to their nearest neighbors or exceptionally high levels of intraspecific variability. Cases of polyphyly in COI trees arising as a result of deep intraspecific divergence are negligible, as the detected cases reflected misidentifications or methodological errors. Taking into consideration variation in sampling effort, we estimate that the true incidence of non-monophyly is ∼23%, but with operational factors still being included. Within the operational factors, we separately assessed the frequency of taxonomic limitations (presence of overlooked cryptic and oversplit species) and identification uncertainties. We observed that operational factors are potentially present in more than half (58.6%) of the detected cases of non-monophyly. Furthermore, we observed that in about 20% of non-monophyletic species and entangled species, the lineages involved are either allopatric or parapatric-conditions where species delimitation is inherently subjective and particularly dependent on the species concept that has been adopted. These observations suggest that species-level non-monophyly in COI gene trees is less common than previously supposed, with many cases reflecting misidentifications, the subjectivity of species delimitation or other operational factors.

Global and regional health effects of future food production under climate change: a modelling study.

BACKGROUND: One of the most important consequences of climate change could be its effects on agriculture. Although much research has focused on questions of food security, less has been devoted to assessing the wider health impacts of future changes in agricultural production. In this modelling study, we estimate excess mortality attributable to agriculturally mediated changes in dietary and weight-related risk factors by cause of death for 155 world regions in the year 2050. METHODS: For this modelling study, we linked a detailed agricultural modelling framework, the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT), to a comparative risk assessment of changes in fruit and vegetable consumption, red meat consumption, and bodyweight for deaths from coronary heart disease, stroke, cancer, and an aggregate of other causes. We calculated the change in the number of deaths attributable to climate-related changes in weight and diets for the combination of four emissions pathways (a high emissions pathway, two medium emissions pathways, and a low emissions pathway) and three socioeconomic pathways (sustainable development, middle of the road, and more fragmented development), which each included six scenarios with variable climatic inputs. FINDINGS: The model projects that by 2050, climate change will lead to per-person reductions of 3·2% (SD 0·4%) in global food availability, 4·0% (0·7%) in fruit and vegetable consumption, and 0·7% (0·1%) in red meat consumption. These changes will be associated with 529,000 climate-related deaths worldwide (95% CI 314,000-736,000), representing a 28% (95% CI 26-33) reduction in the number of deaths that would be avoided because of changes in dietary and weight-related risk factors between 2010 and 2050. Twice as many climate-related deaths were associated with reductions in fruit and vegetable consumption than with climate-related increases in the prevalence of underweight, and most climate-related deaths were projected to occur in south and east Asia. Adoption of climate-stabilisation pathways would reduce the number of climate-related deaths by 29-71%, depending on their stringency. INTERPRETATION: The health effects of climate change from changes in dietary and weight-related risk factors could be substantial, and exceed other climate-related health impacts that have been estimated. Climate change mitigation could prevent many climate-related deaths. Strengthening of public health programmes aimed at preventing and treating diet and weight-related risk factors could be a suitable climate change adaptation strategy. FUNDING: Oxford Martin Programme on the Future of Food.

The effect of a competitor on a model adaptive radiation.

The ecological forces shaping adaptive radiations are of great interest to evolutionary ecologists. Here, we experimentally test the hypothesis that the diversification of a lineage should be limited in the presence of competition from another taxon. We do this by studying a model microbial adaptive radiation (the generation of phenotypic diversity in asexual lineages of the bacterium Pseudomonas fluorescens) in the presence or absence of a competitor (Pseudomonas putida). In a spatially heterogeneous environment, the competitor P. putida reduced P. fluorescens population size only slightly and had no effect on diversification. In a spatially homogeneous environment, the competitor reduced P. fuoresecens population size to a much greater extent. Again the final extent of diversification in P. fluorescens was not affected by the competitor, but early diversification was accelerated. In this environment, P. putida suppressed the growth of a common variant of P. fluorescens and directly or indirectly facilitated the growth of a rare morph. Our results suggest that competition experienced by diversifying lineages may have complex effects on adaptive radiations not fully captured by current theory.

Population genetic structure and secondary symbionts in host-associated populations of the pea aphid complex.

Polyphagous insect herbivores experience different selection pressures on their various host plant species. How this affects population divergence and speciation may be influenced by the bacterial endosymbionts that many harbor. Here, we study the population structure and symbiont community of the pea aphid (Acyrthosiphon pisum), which feeds on a range of legume species and is known to form genetically differentiated host-adapted populations. Aphids were collected from eight legume genera in England and Germany. Extensive host plant associated differentiation was observed with this collection of pea aphids comprising nine genetic clusters, each of which could be associated with a specific food plant. Compared to host plant, geography contributed little to genetic differentiation. The genetic clusters were differentiated to varying degrees, but this did not correlate with their degree of divergence in host use. We surveyed the pea aphid clones for the presence of six facultative (secondary) bacterial endosymbionts and found they were nonrandomly distributed across the aphid genetic clusters and this distribution was similar in the two countries. Aphid clones on average carried 1.4 species of secondary symbiont with those associated with Lathyrus having significantly fewer. The results are interpreted in the light of the evolution of specialization and ecological speciation.