A multi-country study of intussusception in children under 2 years of age in Latin America: analysis of prospective surveillance data

BACKGROUND: Intussusception (IS) is a form of acute intestinal obstruction that occurs mainly in infants and is usually of unknown cause. An association between IS and the first licensed rotavirus vaccine, a reassortant-tetravalent, rhesus-based rotavirus vaccine (RRV-TV), led to the withdrawal of the vaccine. New rotavirus vaccines have now been developed and extensively studied for their potential association with IS. This study aimed to describe the epidemiology and to estimate the incidence of IS in Latin American infants prior to new vaccine introduction. METHODS: Children under 2 years of age representing potential IS cases were enrolled in 16 centers in 11 Latin American countries from January 2003 to May 2005. IS cases were classified as definite, probable, possible or suspected as stated on the Brighton Collaboration Working Group guidelines. RESULTS: From 517 potential cases identified, 476 (92%) cases were classified as definite, 21 probable, 10 possible and 10 suspected for intussusception. Among the 476 definite IS cases, the median age at presentation was 6.4 months with 89% of cases aged <1 year. The male to female ratio was 1.5:1. The incidence of definite IS per 100,000 subject-years ranged from 1.9 in Brazil to 62.4 in Argentina for children <2 years of age, and from 3.8 in Brazil to 105.3 in Argentina for children aged <1 year. Median hospital stay was 4 days with a high prevalence of surgery as the primary treatment (65%). Most cases (88%) made a complete recovery, but 13 (3%) died. No clear seasonal pattern of IS cases emerged. CONCLUSIONS: This study describes the epidemiology and estimates the incidence of IS in Latin American infants prior to the introduction of new rotavirus vaccines. The incidence of IS was found to vary between different countries, as observed in previous studies. TRIAL REGISTRATION: Clinical study identifier 999910/204 (SERO-EPI-IS-204

Factors that Determine the Efficiency Ranking of Second-Best Instruments for Environmental Regulation

Cost-effective policies allow minimizing the compliance costs associated to reaching a desired environmental quality target. However cost reductions associated to the use of these policies are not always significant. In this paper a conceptual model is developed to analyze explicitly the interaction among the factors that determine the compliance costs under two market based policies (the optimal ambient permit system, APS, and an emission permit system, EPS) and two CAC policies (equal percentage reduction, PER and a uniform concentration standard of emissions, STD). Considering a non-uniformly mixed pollutant the model incorporates explicitly the number of polluting sources; the size, in terms of emissions, of each process; the marginal costs of abatement for each process; the concentration of the emitted pollutant at the source; the transfer coefficient that relates emissions at each location with the impact on environmental quality at the receptor; and the desired environmental quality target. A first question addressed using the model. is how each of these factors affects compliance costs under each policy and as a result how the costs of sub-optimal policies compare with those of the optimal policy. The model shows that each factor affect the relative efficiency of each suboptimal policy quite differently. A second issue addressed is the efficiency ranking of second-best instruments under plausible values of each factor. It is shown that (1) APS is significantly less costly than the suboptimal policies in 45% of the cases; (2)EPS is very efficient in 75% of the cases, particularly when sources are clustered around the receptor; (3) a uniform standard performs well in many common situations; and PER is also efficient in some specific cases; (4) there is a high dispersion of results for cost quotients in some specific cases; and (5) relative compliance costs for PER and STD show extreme variations becoming very inefficient in some cases. Extreme values of the cost quotient for EPS are much lower.

Permisos transables frente a la introducción de un combustible limpio: estudio de caso para PM-10 y NOx en Santiago, Chile

Beginning in 1990 a compensation system for PM-10 emissions from point sources was implemented in Santiago, equivalent to a suboptimal emission permit system (EPS). The objective of the system was to reduce compliance costs and to prevent emissions from new sources, forcing them to compensate all emissions with existing sources. The system basically did not operate until 1997, year in which natural gas �a clean fuel� was introduced into Santiago. In this context, this paper examines the following questions: What is the impact of the introduction of natural gas in the applicability of tradeable permits for PM-10 and NOx? Are they justified or are the efficiency gains so small that direct regulation is preferable? The efficiency gains associated to an optimal ambient permit system (APS) are quantified and compared to the simpler EPS. Finally control cost functions are developed for Santiago for fixed point sources and presented in detail.A partir de 1990 se introdujo en Santiago un sistema de compensación de emisiones para controlar las emisiones de PM-10 de fuentes fijas, en principio equivalente a un sistema de permisos de emisión (EPS), instrumento económico subóptimo. Se buscaba con este sistema reducir los costos de cumplimiento e impedir el crecimiento de las emisiones de fuentes fijas al obligar a fuentes nuevas a compensar todas sus emisiones. El sistema básicamente no operó hasta 1997, año en que se introduce el gas natural en Santiago, combustible considerado limpio. En este contexto, este trabajo aborda las siguientes preguntas: ¿Qué impacto ha tenido la introducción del gas natural sobre la aplicabilidad de permisos transables para PM-10 y NOx? ¿Se siguen justificando o las ganancias en eficiencia disminuyen a tal nivel que se puede considerar el uso de instrumentos de regulación directa? También se cuantifican las ganancias en eficiencia asociadas a aplicar u sistema de permisos ambientales (APS) que, a diferencia de un EPS, es óptimo. Finalmente en este trabajo se presentan en detalle las funciones de costos de control para las diversas fuentes fijas de Santiago

International Trade and Sustainability of the Chilean Forestry Sector

In this paper the vulnerability of Chile's forestry trade to environmental threats is explored. The increasing concern for the environment by consumers, together with the life cycle approach to products has created a new context for forest exploitation. The new trend in consumer based voluntary instruments, requiring an increasing use of eco-labels and forestry certification schemes, that can be used as trade barriers, is discussed. In particular the uncertainty related to the definition of sustainable forestry management is examined. The link between this trend and the interests of social and environmental NGO's, represents a potential threat to forestry sector development. These are not theoretical concerns, as exemplified by Chile's forestry sector development in recent years: at the production stage, the use of chlorine has been banned increasing production costs; native forest exploitation and plantations have come under increasing scrutiny, based on allegedly, unsustainable forestry practices; forestry development in Magallanes is being put under intense pressure by NGO's. The result is an abandonment of native forest by forestry firms, and the reduction in new plantations, even though most allegations have a weak base.

Síndrome holandés, regalías mineras y políticas de gobierno para un país dependiente de recursos naturales: el cobre en Chile

Incluye BibliografíaEl desarrollo de Chile ha estado históricamente ligado con la producción y exportación del cobre, actividad que genera importantes ingresos para el sector público y privado. En este documento se analiza con un modelo de equilibrio general dinámico los efectos macroeconómicos, sectoriales y distributivos producidos por un aumento en el precio del cobre y el cobro de una regalía a sus rentas. Además, se simulan políticas de gobierno que apunten a lograr un mayor crecimiento y una mejora en la distribución del ingreso, identificándose tradeoffs entre estas variables tanto en el largo como en el corto plazo. Un aumento del precio internacional del cobre incide en un mayor crecimiento del PIB en el corto y largo plazo, así como en un mayor nivel de ingreso para todos los quintiles; aunque con mayores niveles de desigualdad. Inicialmente se genera un fenómeno de síndrome holandés, que se manifiesta en el corto plazo, afectando a los otros sectores exportadores. Sin embargo, este efecto es transitorio y tiende a revertirse lentamente generando mayores incrementos en el PIB. La incorporación de una regalía en este contexto controla el explosivo aumento en la producción del cobre, atenúa el efecto del síndrome holandés y aumenta la diversificación de la canasta exportadora. Sin embargo, el impacto de este efecto amortiguador depende de la forma como se utilicen los ingresos provenientes de la regalía. Este documento analiza la importancia de un adecuado diseño de políticas públicas que apunten hacia un mayor crecimiento económico, una reducción de los impactos negativos sobre otros sectores y una menor brecha en la distribución del ingreso

Permisos transables frente a la introducción de un combustible limpio: estudio de caso para PM-10 y NOx en Santiago, Chile

A partir de 1990 se introdujo en Santiago un sistema de compensación de emisiones para controlar las emisiones de PM-10 de fuentes fijas, en principio equivalente a un sistema de permisos de emisión (EPS), instrumento económico subóptimo. Se buscaba con este sistema reducir los costos de cumplimiento e impedir el crecimiento de las emisiones de fuentes fijas al obligar a fuentes nuevas a compensar todas sus emisiones. El sistema básicamente no operó hasta 1997, año en que se introduce el gas natural en Santiago, combustible considerado limpio. En este contexto, este trabajo aborda las siguientes preguntas: ¿Qué impacto ha tenido la introducción del gas natural sobre la aplicabilidad de permisos transables para PM-10 y NOx? ¿Se siguen justificando las ganancias en eficiencia disminuyen a tal nivel que se puede considerar el uso de instrumentos de regulación directa? También se cuantifican las ganancias en eficiencia asociadas a aplicar un sistema de permisos ambientales (APS) que, a diferencia de unNatural Resource, pollution in air.

Comparing the Net Benefits of Incentice Based and Command and Control Regulations in a Developing Context: the Case of Santiago, Chile

There are numerous studies that establish the magnitude of the static efficiency gains made possible through the use of a cost effective ambient permit system (APS) compared to command and control (CAC) or other suboptimal instruments such as an emission permit system (EPS). However the cost effectiveness of APS rests both on the efficiency gains related to equalizing marginal costs of reduction and a lower degree of required control. As a result of this latter factor, CAC and EPS generally impose concentration reductions higher than required by the target air quality standard and also by APS. In developing contexts, as a result of high levels of pollution and only recent introduction of control policies, health benefits of reducing pollution significantly can be expected to be high whereas the costs may still be relatively low. Consequently the excess reductions may produce net benefits -benefits of improved air quality minus compliance costs-. This paper evaluates for Santiago whether reduced concentrations below the level of the standard as a result of suboptimal policies resultin health improvements that produce greater net benefits than incentive based approaches. The results show that considering uniform air quality targets and for the range of technologically plausible control options in Santiago, suboptimal CAC and EPS policies result in higher net benefits than APS.