Greenhouse gas emissions from agricultural residue burning have increased by 75 % since 2011 across India

Quantifying crop residue burning across India is imperative, owing to its adverse impacts on public health, the environment, and agricultural productivity. Specific information about the extent and characteristics of agricultural crop burning can verify the emission potential of agricultural systems and thereby facilitate targeted dissemination of agricultural innovations and support policymakers in mitigating the harmful effects. With a focus on district-level burning estimates, our study provides a comprehensive seasonal analysis of agricultural burning in India, including burned area, dry matter burned, and gaseous emissions for seven major crops from 2011 to 2020. To quantify the actual residues burned, we developed a remote sensing-based approach that incorporates the monitoring of agricultural burned area to quantify the actual residues burned. Including this satellite measure of the burned area greatly improves emissions estimates and minimizes error compared to typical approaches, which instead use an assumed fraction of total residues that are burned for each crop type. We estimated that emissions have increased by approximately 75 % for CO and Greenhouse gasses - CO2, CH4 and N2O - from 2011 to 2020. Total CO2e emissions increased from ~19,340 Gg.yr-1 in 2011 to ~33,834 Gg.yr-1 in 2020. Most emissions occurred during end of the Kharif season, followed by Rabi, caused by the burning of rice and wheat residues. Among the Indian states, Punjab has the highest burning activity, with 27 % (2.0 million hectares) of its total cultivated area burned in 2020. Interestingly, Madhya Pradesh has emerged as the second-largest contributor, accounting for 30 % of the total burned area across India in 2020. Our study demonstrates how satellite data can be used to map agricultural residue burning at scale, and this information can provide crucial insights for policy framing, targeting, and interventions to manage agricultural residues without compromising air quality and climate.

Health effects and externalities of the popularization of sanitary toilets: evidence from Rural China

BACKGROUND

This study aimed to assess the impact of the increased prevalence of sanitary toilets in rural areas on the health of rural residents, and whether the popularity thereof has a positive externality. This study investigates whether the broader use of sanitary toilets has had a positive effect on the health of people who do not have access to them.

METHODS

Data from the China Family Panel Studies from 2012 to 2014 and a two-way fixed effect model were used to investigate the relationship between the prevalence of village sanitary toilets and the health of rural residents of all ages.

RESULTS

The results showed that: (1) the increase in the prevalence of sanitary toilets in villages is conducive to improving the health level of rural residents; (2) the widespread adoption of sanitary toilets in rural areas has improved the health of not only residents with access to these toilets but also residents without access; (3) the health of children is more sensitive to improvements in sanitary conditions of toilets; and (4) there are significant regional differences in the impact of the popularity of sanitary toilets on the health of rural residents.

CONCLUSIONS

This study found that the popularity of sanitary toilets has externalities, improving not only the health of residents who use them but also the health of other residents. This study enriches the literature in the field of health effects of sanitation improvement, while providing a reference for developing countries to further enhance the living environment in rural areas. In the future, the popularization of sanitary toilets should be vigorously promoted to reduce the incidence of diseases.

Urbanization and transport energy consumption in African countries

Transport energy use contributes to pollution, so it generates negative externalities. This paper analyzes the effect of urbanization on the transport final energy consumption in African countries. To that end, the paper applies the panel threshold regression (PTR) model for a panel of 25 African countries over the period 1992-2017. The findings show that there is a significant positive relationship between total and per capita transport energy consumption and the share of the urban population in the total population. Thus, urbanization fosters transport energy consumption, either per capita energy consumption or total energy consumption. Therefore, the results from this study suggest that African countries should promote sustainable urbanization in terms of transportation.

The effect of altruism on COVID-19 vaccination rates

BACKGROUND

After the emergence of the first vaccines against the COVID-19, public health authorities have promoted mass vaccination in order to achieve herd immunity and reduce the effects of the disease. Vaccination rates have differed between countries, depending on supply (availability of resources) and demand (altruism and resistance to vaccination) factors.

METHODS

This work considers the hypothesis that individuals' health altruism has been an important factor to explain the different levels of vaccination between countries, using the number of transplants as a proxy for altruism. Taking European Union's countries to remove, as far as possible, supply factors that might affect vaccination, we carry out cross-sectional regressions for the most favorable date of the vaccination process (maximum vaccination speed) and for each month during the vaccination campaign.

RESULTS

Our findings confirm that altruism has affected vaccination rates against the COVID-19. We find a direct relationship between transplants rates (proxy variable) and vaccination rates during periods in which the decision to be vaccinated depended on the individual's choice, without supply restrictions. The results show that other demand factors have worked against vaccination: political polarization and belonging to the group of countries of the former Eastern bloc.

CONCLUSIONS

Altruism is a useful tool to define future vaccination strategies, since it favors the individuals' awareness for vaccination.

Inframarginal externalities: COVID-19, vaccines, and universal mandates

COVID-19 vaccine mandates are in place or being debated across the world. Standard neoclassical economics argues that the marginal social benefit from vaccination exceeds the marginal private benefit; everyone vaccinated against a given infectious disease protects others by not transmitting the disease. Consequently, private levels of vaccination will be lower than the socially optimal levels due to free-riding, which requires mandates to overcome the problem. We argue that universal mandates based on free-riding are less compelling for COVID-19. We argue that because the virus can be transmitted even after receiving the vaccine, most of the benefits of the COVID-19 vaccine are internalized: vaccinated individuals are protected from the worst effects of the disease. Therefore, any positive externality may be inframarginal or policy irrelevant. Even when all the benefits are not internalized by the individual, the externalities mainly are local, mostly affecting family and closely associated individuals, requiring local institutional (private and civil society) arrangements to boost vaccine rates, even in a global pandemic. Economists and politicians must justify such universal vaccine mandates on some basis other than free-riding.

Competition among public good providers for donor rewards

We present experimental evidence for decision settings where public good providers compete for endogenous rewards which are donations (transfers) offered by outside donors. Donors receive benefits from public good provision but cannot provide the good themselves. The performance of three competition mechanisms is examined in relation to the level of public good provision and transfers offered by donors. In addition to a contest where transfers received by public good providers are proportional to effort, we study two contests with exclusion from transfers, namely a winner-takes-all and a loser-gets-nothing. We compare behavior in these three decision settings to the default setting of no-contest (no-transfers). Results for this novel decision environment with endogenous transfers show that donors offer transfers (contest prizes) at similar levels across contests and contributions to the public good are not significantly different in the three contests settings, but are consistently and significantly higher in all contests compared to the setting with no-transfers. Initially, the winner-takes-all setting leads to a significantly higher increase in public good contributions compared to the other two contests; but this difference diminishes across decision rounds.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10683-022-09766-7.

Optimal vaccine subsidies for endemic diseases

In Goodkin-Gold et al. (2021), we analyzed optimal subsidies for a vaccine against an epidemic outbreak like Covid-19. This companion paper alters the underlying epidemiological model to suit endemic diseases requiring continuous vaccination of new cohorts-also suiting an epidemic like Covid-19 if, following Gans (2020), one assumes peaks are leveled by social distancing. We obtain qualitatively similar results: across market structures ranging from perfect competition to monopoly, the subsidy needed to induce first-best vaccination coverage on the private market is highest for moderately infectious diseases, which invite the most free riding; extremely infectious diseases drive more consumers to become vaccinated, attenuating externalities. Stylized calibrations to HIV, among other diseases, suggest that first-best subsidies can be exorbitantly high when suppliers have market power, rationalizing alternative policies observed in practice such as bulk purchases negotiated by the government on behalf of the consumers.

Maternal human capital and infants' health outcomes: Evidence from minimum dropout age policies in the US

The purpose of this cross-sectional study is to examine the causal relationship of maternal education and infants' health outcomes. Using birth certificate data over the years 1970–2004 and exploiting the space-time variation in Minimum Dropout Age laws to solve the endogeneity of education, we find a sizeable effect of mothers' education on their birth outcomes. An additional year of maternal education is associated with a reduction in incidences of low birth weight and preterm birth by 15.2 and 12.7 percent, respectively. The estimates are robust across various specifications and even when allowing mothers’ cohort-of-birth to vary across regions. The results suggest that the candidate mechanisms of impact include improvements in timing, quantity, and quality of prenatal care, lower negative health behavior during pregnancy such as smoking and drinking, and higher spousal education.

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We provide causal evidence on the effect of mothers' education on birth outcomes.

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We use Minimum Dropout Age policies as the instrument.

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Mother education has significant impact on infants' birth outcomes.

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Candidate mechanisms include improvements in timing, quantity, and quality of prenatal care.

On Coase and COVID-19

From an epidemiological perspective, the COVID-19 pandemic is a public health crisis. From an economic perspective, it is an externality and a social cost. Strikingly, almost all economic policy to address the infection externality has been formulated within a Pigovian analysis of implicit taxes and subsidies directed by a social planner drawing on social cost-benefit analysis. In this paper we examine the alternative economic methodology of the externality. We seek to understand how an exchange-focused and institutional analysis provides a better understanding of how to minimise social cost. Our Coasean framework allows us to further develop a comparative institutional analysis of the pandemic response.

Intergenerational health effects of Medicaid

This paper investigates the effects of the introduction of Medicaid during the 1960s on next generations' birth outcomes. A federal mandate that all states must widen the coverage to all cash welfare recipients generated cross-state variations in Medicaid eligibility, specifically among nonwhites who largely overrepresented the target population. I implement a reduced-form difference-in-differences strategy that compares the birth outcomes of mothers born in states with higher cash welfare recipiency versus low welfare recipiency and different years relative to the Medicaid implementation year. Using Natality data (1970-2004), I find that Medicaid significantly improves birth outcomes. The effects are considerably larger among nonwhites, specifically blacks. The effects do not appear to be driven by preexisting trends in birth outcomes, preexisting trends in households' socioeconomic characteristics, changes in other welfare expenditures, and selective fertility. A back-of-an-envelope calculation points to a minimum of 3.9% social externality of Medicaid through income rises due to next generations' improvements in birth outcomes.

Towards a paradigm shift in environmental health decision-making: a case study of oxybenzone

BACKGROUND

Technological advancements make lives safer and more convenient. Unfortunately, many of these advances come with costs to susceptible individuals and public health, the environment, and other species and ecosystems. Synthetic chemicals in consumer products represent a quintessential example of the complexity of both the benefits and burdens of modern living. How we navigate this complexity is a matter of a society's values and corresponding principles.

OBJECTIVES

We aimed to develop a series of ethical principles to guide decision-making within the landscape of environmental health, and then apply these principles to a specific environmental chemical, oxybenzone. Oxybenzone is a widely used ultraviolet (UV) filter added to personal care products and other consumer goods to prevent UV damage, but potentially poses harm to humans, wildlife, and ecosystems. It provides an excellent example of a chemical that is widely used for the alleged purpose of protecting human health and product safety, but with costs to human health and the environment that are often ignored by stakeholders.

DISCUSSION

We propose six ethical principles to guide environmental health decision-making: principles of sustainability, beneficence, non-maleficence, justice, community, and precautionary substitution. We apply these principles to the case of oxybenzone to demonstrate the complex but imperative decision-making required if we are to address the limits of the biosphere's regenerative rates. We conclude that both ethical and practical considerations should be included in decisions about the commercial, pervasive application of synthetic compounds and that the current flawed practice of cost-benefit analysis be recognized for what it is: a technocratic approach to support corporate interests.

The drawbridge of nature: Evolutionary complexification as a generation and novel interpretation of coding systems

The phenomenon of evolutionary complexification corresponds to the generation of new coding systems (defined as а codepoiesis by Marcello Barbieri). The whole process of generating novel coding statements that substantiate organizational complexification leads to an expansion of the system that incorporates externality to support newly generated complex structures. During complexifying evolution, the values are assigned to the previously unproven statements via their encoding by using new codes or rearranging the old ones. In this perspective, living systems during evolution continuously realize the proof of Gödel's theorem. In the real physical world, this realization is grounded in the irreversible reduction of the fundamental uncertainty appearing in the self-referential process of internal measurement performed by living systems. It leads to the formation of reflexive loops that establish novel interrelations between the biosystem and the external world and provide a possibility of active anticipatory transformation of externality. We propose a metamathematical framework that can account for the underlying logic of codepoiesis, outline the basic principles of the generation of new coding systems, and describe main codepoietic events in the course of progressive biological evolution. The evolutionary complexification is viewed as a metasystem transition that results in the increase of external work by the system based on the division of labor between its components.

Beyond the social cost of carbon: Negative emission technologies as a means for biophysically setting the price of carbon

The social cost of carbon (SCC) is an estimate of the costs that society will incur because of the emission of one tonne of CO₂. Because of the large uncertainties in the effects of climate change and the subjectivity of the discount rate, estimates of SCC range widely, from - 10.2 to 105 213$ t^-1 in 2010 USD. Despite this range, the SCC has been used or proposed as a basis for a wide variety of policymaking including cost-benefit analysis and carbon taxes. The SCC suffers from several practical and philosophical weaknesses: it is anthropocentric, it neglects the acidification of oceans, it assumes that quantifiable economic variables like GDP are the primary costs that humans will experience from climate change, and it is impossible to quantify objectively. Further, the ethical implications of a carbon pricing policy include both the value of the carbon price, and the use of revenues generated by the policy. Thus, revenue neutral carbon policies as in some SCC-based proposals, are unlikely to be just. Here, we propose that the cost of emerging negative-emission technologies would be an alternative means for setting a carbon price and avoid these philosophical and practical weaknesses.

A comprehensive framework for considering additional unintended consequences in economic evaluation

Background

In recent years there has been a growth in economic evaluations that consider indirect health benefits to populations due to advances in mathematical modeling. In addition, economic evaluations guidelines have suggested the inclusion of impact inventories to include non-health direct and indirect consequences. We aim to bring together this literature, together with the broader literature on internalities and externalities to propose a comprehensive approach for analysts to identify and characterize all unintended consequences in economic evaluations.

Methods

We present a framework to assist analysts identify and characterize additional costs and effects beyond that of direct health impact primarily intended to be influenced by the intervention/technology. We build on previous checklists to provide analysts with a comprehensive framework to justify the inclusion or exclusion of effects, supporting the use of current guidelines, to ensure any unintended effects are considered. We illustrate this framework with examples from immunization. These were identified from a previous systematic review, PhD thesis work, and general search scoping in PubMed databases.

Results

We present a comprehensive framework to consider additional consequences, exemplified by types and categories. We bring this and other guidance together to assist analysts identify possible unintended consequences whether taking a provider or societal perspective.

Conclusions

Although there are many challenges ahead to standardize the inclusion of additional consequences in economic evaluation, we hope by moving beyond generic statements to reporting against a comprehensive framework of additional effects we can support further consistency in this aspect of cost-effectiveness analysis going forward.

Portion size influences intake in Samburu Kenyan people not exposed to the Western obesogenic environment

For people in the modernized food environment, external factors like food variety, palatability, and ubiquitous learned cues for food availability can overcome internal, homeostatic signals to promote excess intake. Portion size is one such external cue; people typically consume more when served more, often without awareness. Though susceptibility to external cues may be attributed to the modernized, cue-saturated environment, there is little research on people living outside that context, or with distinctly different food norms. We studied a sample of Samburu people in rural Kenya who maintain a traditional, semi-nomadic pastoralist lifestyle, eat a very limited diet, and face chronic food insecurity. Participants (12 male, 12 female, aged 20-74, mean BMI = 18.4) attended the study on two days and were provided in counterbalanced order an individual serving bowl containing 1.4 or 2.3 kg of a familiar bean and maize stew. Amount consumed was recorded along with post-meal questions in their dialect about their awareness of intake amount. Data were omitted from two participants who consumed the entire portion in a session. Even though the 'smaller' serving was a very large meal, participants consumed 40% more when given the larger serving, despite being unable to reliably identify which day they consumed more food. This result in the Samburu demonstrates the portion size effect is not a by-product of the modern food environment and may represent a more fundamental feature of human dietary psychology.

Livestock Disease Management for Trading Across Different Regulatory Regimes

The maintenance of livestock health depends on the combined actions of many different actors, both within and across different regulatory frameworks. Prior work recognised that private risk management choices have the ability to reduce the spread of infection to trading partners. We evaluate the efficiency of farmers' alternative biosecurity choices in terms of their own-benefits from unilateral strategies and quantify the impact they may have in filtering the disease externality of trade. We use bovine viral diarrhoea (BVD) in England and Scotland as a case study, since this provides an example of a situation where contrasting strategies for BVD management occur between selling and purchasing farms. We use an agent-based bioeconomic model to assess the payoff dependence of farmers connected by trade but using different BVD management strategies. We compare three disease management actions: test-cull, test-cull with vaccination and vaccination alone. For a two-farm trading situation, all actions carried out by the selling farm provide substantial benefits to the purchasing farm in terms of disease avoided, with the greatest benefit resulting from test-culling with vaccination on the selling farm. Likewise, unilateral disease strategies by purchasers can be effective in reducing disease risks created through trade. We conclude that regulation needs to balance the trade-off between private gains from those bearing the disease management costs and the positive spillover effects on others.

Conceptual models underlying economic analysis of animal health and welfare with the inclusion of three components: people, products and resources

Infectious animal diseases can spill across farm boundaries, so effective management requires coordinated responses. Costs and benefits from the management of infectious diseases are such that those who make the decisions have weak incentives to act, the levels of goods and services produced from animal agriculture are probably smaller than is socially optimal and resources are likely wasted. This work provides an overview of the existing literature on conceptual economic models in animal disease management, paying particular attention to inadequate incentives to make the required biosecurity efforts. A disease transmission model follows, emphasising policy and management issues which need to be addressed to enhance the benefits that consumers and producers obtain from animal protein markets. The article concludes with comments and suggestions on tackling infectious disease as a public good, and on directions for future research.

Shadow prices of emerging pollutants in wastewater treatment plants: Quantification of environmental externalities

Conventional wastewater treatment plants (WWTPs) are designed to remove mainly the organic matter, nitrogen and phosphorus compounds and suspended solids from wastewater but are not capable of removing chemicals of human origin, such as pharmaceutical and personal care products (PPCPs). The presence of PPCPs in wastewater has environmental effects on the water bodies receiving the WWTP effluents and renders the effluent as unsuitable as a nonconventional water source. Considering PPCPs as non-desirable outputs, the shadow prices methodology has been implemented using the output distance function to measure the environmental benefits of removing five PPCPs (acetaminophen, ibuprofen, naproxen, carbamazepine and trimethoprim) from WWTP effluents discharged to three different ecosystems (wetland, river and sea). Acetaminophen and ibuprofen show the highest shadow prices of the sample for wetland areas. Their values are 128.2 and 11.0 €/mg respectively. These results represent a proxy in monetary terms of the environmental benefit achieved from avoiding the discharge of these PPCPs in wetlands. These results suggest which PPCPs are urgent to remove from wastewater and which ecosystems are most vulnerable to their presence. The findings of this study will be useful for the plant managers in order to make decisions about prioritization in the removal of different pollutants.

The impact of city epidemics on rural labor market: The Korean Middle East Respiratory Syndrome case

This study compared the changes in employment in urban areas in Korea, where a large number of people were quarantined by the Middle East Respiratory Syndrome epidemic, to those in rural areas, where only a small number of people were quarantined using the difference-in-difference approach. The results indicate that the urban labor market experienced a direct effect in terms of a reduction in employment of the group vulnerable to the epidemic while the rural labor market experienced an indirect effect on its economy through a reduction in employment resulting from a decline in consumption and leisure activities. If one looks into the employment in the accommodation and leisure industry, which sustained the most severe blow, dropped to its lowest level right after the Middle East Respiratory Syndrome outbreak. The rural leisure and accommodation industries are highly likely to be dependent on consumption and spending from urban areas. The results suggest that the rural labor market was influenced by the spillover/external effects caused by behavioral changes among people in urban areas due to fear of infection. Thus, this empirical analysis can be used to customize policy to support regions that can be negatively impacted by spillovers due to epidemic in order to respond against economic stresses.

External costs of PM2.5 pollution in Beijing, China: Uncertainty analysis of multiple health impacts and costs

Some cities in China are facing serious air pollution problems including high concentrations of particles, SO₂ and NO_x. Exposure to PM2.5, one of the primary air pollutants in many cities in China, is highly correlated with various adverse health impacts and ultimately represents a cost for society. The aim of this study is to assess health impacts and external costs related to PM2.5 pollution in Beijing, China with different baseline concentrations and valuation methods. The idea is to provide a reasonable estimate of the total health impacts and external cost due to PM2.5 pollution, as well as a quantification of the relevant uncertainty. PM2.5 concentrations were retrieved for the entire 2012 period in 16 districts of Beijing. The various PM2.5 related health impacts were identified and classified to avoid double counting. Exposure-response coefficients were then obtained from literature. Both the value of statistical life (VSL) and the amended human capital (AHC) approach were applied for external costs estimation, which could provide the upper and lower bound of the external costs due to PM2.5. To fully understand the uncertainty levels, the external cost distribution was determined via Monte Carlo simulation based on the uncertainty of the parameters such as PM2.5 concentration, exposure-response coefficients, and economic cost per case. The results showed that the external costs were equivalent to around 0.3% (AHC, China's guideline: C₀ = 35 μg/m³) to 0.9% (VSL, WHO guideline: C₀ = 10 μg/m³) of regional GDP depending on the valuation method and on the assumed baseline PM2.5 concentration (C₀). Among all the health impacts, the economic loss due to premature deaths accounted for more than 80% of the overall external costs. The results of this study could help policymakers prioritizing the PM2.5 pollution control interventions and internalize the external costs through the application of economic policy instruments.

How externalities impact an evaluation of strategies to prevent antimicrobial resistance in health care organizations

Background

The rates of antimicrobial-resistant organisms (ARO) continue to increase for both hospitalized and community patients. Few resources have been allocated to reduce the spread of resistance on global, national and local levels, in part because the broader economic impact of antimicrobial resistance (i.e. the externality) is not fully considered when determining how much to invest to prevent AROs, including strategies to contain antimicrobial resistance, such as antimicrobial stewardship programs. To determine how best to measure and incorporate the impact of externalities associated with the antimicrobial resistance when making resource allocation decisions aimed to reduce antimicrobial resistance within healthcare facilities, we reviewed the literature to identify publications which 1) described the externalities of antimicrobial resistance, 2) described approaches to quantifying the externalities associated with antimicrobial resistance or 3) described macro-level policy options to consider the impact of externalities. Medline was reviewed to identify published studies up to September 2016.

Main body

An externality is a cost or a benefit associated with one person’s activity that impacts others who did not choose to incur that cost or benefit. We did not identify a well-accepted method of accurately quantifying the externality associated with antimicrobial resistance. We did identify three main methods that have gained popularity to try to take into account the externalities of antimicrobial resistance, including regulation, charges or taxes on the use of antimicrobials, and the right to trade permits or licenses for antimicrobial use. To our knowledge, regulating use of antimicrobials is the only strategy currently being used by health care systems to reduce antimicrobial use, and thereby reduce AROs. To justify expenditures on programs that reduce AROs (i.e. to formally incorporate the impact of the negative externality of antimicrobial resistance associated with antimicrobial use), we propose an alternative approach that quantifies the externalities of antimicrobial use, combining the attributable cost of AROs with time-series analyses showing the relationship between antimicrobial utilization and incidence of AROs.

Conclusion

Based on the findings of this review, we propose a methodology that healthcare organizations can use to incorporate the impact of negative externalities when making resource allocation decisions on strategies to reduce AROs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13756-017-0211-2) contains supplementary material, which is available to authorized users.

Expressing air pollution-induced health-related externalities in physical terms with the help of DALYs

The unintended impacts of industrial activity on human health and the environment have regularly been assessed and monetised (referred to as "external costs"). External costs are, however, a rather abstract aggregate so that decision makers cannot easily relate them to tangible impacts. At the same time, physical health impact indicators have different units that cannot readily be compared and communicated in a joint way. To support better informed decisions at policy or company level, we propose and demonstrate a way to facilitate communication on non-monetized, that is, physical health indicators quantified in studies. The concept Disability-Adjusted Life Year (DALY) is chosen as metric due to its widespread use. We establish a comprehensive and consistent set of six health endpoints caused by particles and ozone, and derive related up-to-date DALYs. Further we apply the DALY values to a French smart grid demonstration project. Owing to its size, the gains in terms of reduced DALYs are however small. In contrast to external cost assessments, in the frame of which morbidity endpoints usually contribute to around 10-15%, they are found to be insubstantial in the overall DALY score (i.e. below 1%). This is because DALYs only consider time losses weighted by severity while external costs also factor in further welfare effects, i.e. combining resource, disutility and opportunity costs of illness. As a result, methodological limitations, mainly existing for the morbidity-related DALY values, appear to be less of concern. Overall, using the DALYs with and without morbidity impacts is justifiable. Either choice in the communication of health-related physical externalities induces the need to explain the limitations in terms of the treatment of morbidity endpoints (notably their definition and the disability weights used) or their complete disregard.

Western diet and the weakening of the interoceptive stimulus control of appetitive behavior

In obesogenic environments food-related external cues are thought to overwhelm internal cues that normally regulate energy intake. We investigated how this shift from external to internal stimulus control might occur. Experiment 1 showed that rats could use stimuli arising from 0 and 4h food deprivation to predict sucrose delivery. Experiment 2 then examined (a) the ability of these deprivation cues to compete with external cues and (b) how consuming a Western-style diet (WD) affects that competition. Rats were trained to use both their deprivation cues and external cues as compound discriminative stimuli. Half of the rats were then placed on WD while the others remained on chow, and external cues were removed to assess learning about deprivation state cues. When tested with external cues removed, chow-fed rats continued to discriminate using only deprivation cues, while WD-fed rats did not. The WD-fed group performed similarly to control groups trained with a noncontingent relationship between deprivation cues and sucrose reinforcement. Previous studies provided evidence that discrimination based on interoceptive deprivation cues depends on the hippocampus and that WD intake could interfere with hippocampal functioning. A third experiment assessed the effects of neurotoxic hippocampal lesions on weight gain and on sensitivity to the appetite-suppressing effects of the satiety hormone cholecystokinin (CCK). Relative to controls, hippocampal-lesioned rats gained more weight and showed reduced sensitivity to a 1.0ug but not 2.0 or 4.0ug CCK doses. These findings suggest that WD intake reduces utilization of interoceptive energy state signals to regulate appetitive behavior via a mechanism that involves the hippocampus.

Assaults, murders and walkers: The impact of violent crime on physical activity

We investigate an underexplored externality of crime: the impact of violent crime on individuals' participation in walking. For many adults walking is the only regular physical activity. We use a sample of nearly 1 million people in 323 small areas in England between 2005 and 2011 matched to quarterly crime data at the small area level. Within area variation identifies the causal effect of local violent crime on walking and a difference-in-difference analysis of two high-profile crimes corroborates our results. We find a significant deterrent effect of violent crime on walking that translates into a drop in overall physical activity.

Costs of food waste in South Africa: Incorporating inedible food waste

The economic, social and environmental costs of food waste are being increasingly recognised. Food waste consists of both edible and inedible components. Whilst wastage of edible food is problematic for obvious reasons, there are also costs associated with the disposal of the inedible fraction to landfill. This is the third in a series of papers examining the costs of food waste throughout the value chain in South Africa. The previous papers focused on the edible portion of food waste. In this paper, costs associated with inedible food waste in South Africa are estimated, in terms of the value foregone by not recovering this waste for use in downstream applications, such as energy generation or composting; as well as costs associated with disposal to landfill. Opportunity costs are estimated at R6.4 (US$0.64) billion per annum, or R2668 (US$266) per tonne. Adding this to the previous estimate for edible food waste of R61.5 billion per annum (in 2012 prices; equivalent to R65 billion in 2013 prices) results in a total opportunity cost of food waste in South Africa (in terms of loss of a potentially valuable food source or resource) of R71.4 (US$7.14) billion per annum, or R5667 (US$567) per tonne. Thereafter, estimates of the costs associated with disposal of this food waste to landfill, including both financial costs and externalities (social and environmental costs), are taken into account. These costs amount to R255 (US$25) per tonne, giving rise to a total cost of food waste in South Africa of R75 billion (US$7.5 billion) per annum, or R5922 (US$592) per tonne. This is equivalent to 2.2% of South Africa's 2013 GDP.

Externalities in a life cycle model with endogenous survival

We study socially vs individually optimal life cycle allocations of consumption and health, when individual health care curbs own mortality but also has a spillover effect on other persons' survival. Such spillovers arise, for instance, when health care activity at aggregate level triggers improvements in treatment through learning-by-doing (positive externality) or a deterioration in the quality of care through congestion (negative externality). We combine an age-structured optimal control model at population level with a conventional life cycle model to derive the social and private value of life. We then examine how individual incentives deviate from social incentives and how they can be aligned by way of a transfer scheme. The age-patterns of socially and individually optimal health expenditures and the transfer rate are derived. Numerical analysis illustrates the working of our model.