Lead poisoning in South African children: the hazard is at home

Lead is a toxic heavy metal that has been used extensively in modern society, causing widespread environmental contamination even in isolated parts of the world. Irrefutable evidence associates lead at different exposure levels with a wide spectrum of health and social effects, including mild intellectual impairment, hyperactivity, shortened concentration span, poor school performance, violent/aggressive behavior, and hearing loss. Lead has an impact on virtually all organ systems, including the heart, brain, liver, kidneys, and circulatory system, resulting in coma and death in severe cases. In recent years, a consensus was reached regarding the absence of a threshold for the key health effects associated with lead exposure and the permanent and irreversible nature of many health and social consequences of lead exposure. The public health problem of environmental lead exposure has been widely investigated in developed countries like the United States of America, where actions taken have led to significant reductions in children's blood lead concentrations. In contrast, there is a relative dearth of information and action regarding lead poisoning in developing countries, particularly in African countries, despite evidence of widespread and excessive childhood lead exposure. In this paper, we will review the information from available published papers, the 'grey literature', and unpublished reports to give an overview of lead exposure in South African children over the past two decades, with particular emphasis on sources of exposure in the home environment.     

儿童铅中毒及防治的回顾与新进展

铅是一种多亲和性毒物,主要损害中枢神经系统,尤其是发育中的大脑。儿童血铅目前公认没有安全阈值,血铅水平仅用于界定是否需要实施干预措施。儿童铅中毒已成为一个全球性的公共安全问题。随着我国近年来对环境铅污染的治理,儿童铅中毒防治取得了实质性进步。儿童铅中毒重在预防,健康教育和减少铅暴露机会为主,排铅治疗为辅。驱铅主要药物目前仍是沿用了数十年的金属络合剂,儿童用药安全性尚存争议。经口暴露作为儿童铅摄入的主要途径,阻断铅消化道吸收有望成为儿童铅中毒防治的新举措之一。     

Too easily lead? Health effects of gasoline additives.

Octane-enhancing constituents of gasoline pose a number of health hazards. This paper considers the relative risks of metallic (lead, manganese), aromatic (e.g., benzene), and oxygenated additives in both industrialized and developing countries. Technological advances, particularly in industrialized countries, have allowed the progressive removal of lead from gasoline and the increased control of exhaust emissions. The developing world, by contrast, has relatively lax environmental standards and faces serious public health problems from vehicle exhaust and the rapid increase in automobile use. Financial obstacles to the modernization of refineries and vehicle fleets compound this problem and the developing world continues to import large quantities of lead additives and other hazardous materials. Progress in decreasing environmental health problems depends both on the adoption of international public health standards as well as efforts to decrease dependence on the private automobile for urban transport.     

Environmental lead toxicity and nutritional factors

Environmental lead toxicity is an old but persistent public health problem throughout the world and children are more susceptible to lead than adults because of their hand to mouth activity, increased respiratory rates and higher gastrointestinal absorption per unit body weight. In the last decade children's blood lead levels have fallen significantly in a number of countries. Despite this reduction, childhood lead toxicity continues to be a major public health problem for certain at-risk groups of children, and concern remains over the effects of lead on intellectual development. The currently approved clinical intervention method is to give chelating agents, which bind and removed lead from lead burdened tissues. Studies indicate, however, that there is a lack of safety and efficacy when conventional chelating agents are used. Several studies are underway to determine the beneficial effect of nutrients supplementation following exposure to lead. Data suggest that nutrients may play an important role in abating some toxic effects of lead. To explain the importance of using exogenous nutrients in treating environmental lead toxicity the following topics are addressed: (i) different sources of lead exposure/current blood lead levels and (ii) protective effects of nutrients supplementation (some essential elements and vitamins) in lead toxicity.     

Environmental Pollution and Blood Lead Levels in Nigeria: Who is Unexposed?

Abstract

While blood lead levels (BLLs) in many western countries have progressively declined since 1976, in Nigeria high BLL continue to be documented not only in exposed workers but also in "unexposed" control subjects. The problem of environmental lead exposure has hitherto gone unaddressed by both researchers and health policy makers in Nigeria despite the immense public health importance. Continued high BLLs in Nigeria cast doubt on researchers' ability to find real "unexposed control subjects" in future studies, and point to the importance of controlling environmental lead exposures.     

Health hazards by lead exposure: evaluation using ASV and XRF

Globally, of many toxic heavy metals, lead is the most widely used for various purposes, resulting in a variety of health hazards due to environmental contamination. Lead in the workplace enters the workers through inhalation of lead-contaminated air, by ingestion, and sometimes through dermal exposure. Furthermore, exposure outside the workplace can occur from inhalation of lead-contaminated air, ingestion of lead-contaminated dust and soil, consumption of lead polluted water, lead adulterated food and lead supplemented medicine. In the present study, an evaluation of blood lead was carried out with the aid of a 3010 B lead analyser, based on the principle of anodic stripping voltametry (ASV), and environmental lead in paint, soil and dust samples by a field portable X-ray fluorescence (XRF) analyser. This revealed a high incidence of lead toxicity in most of the lead-based industrial workers in the four facilities tested in India and high levels of lead in the environmental samples. Developed countries have complied with the global standards for regulating environmental lead poisoning in the workplace, eliminating to some degree excessive exposure to lead. A developing country, such as India, can tackle this problem by implementing national and international policies. The US Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency (EPA) regulations, which are of prime importance, or similar regulations, can be adapted for use in India and implemented to minimize lead exposure and to reduce the resultant health hazards.     

Public health requirements for rapid progress in global health

Abstract

Effective public health interventions can save hundreds of millions of lives in developing countries, as well as create broad social and economic benefits. Unfortunately, public health approaches and solutions applied in developed countries are often assumed to be inappropriate or unattainable in developing countries. This has sometimes forestalled effective interventions in parts of the world where they are most needed, despite conditions that now facilitate lasting solutions to both long-standing and emerging global public health problems. Core public health functions are similar regardless of a country's income level. Although some resource-intensive approaches from industrialised nations are inappropriate in less developed countries, many basic public health measures achieved decades ago in developed countries are urgently needed, highly appropriate, extremely cost-effective and eminently attainable in developing countries today. About half of the disease burden in low and middle-income countries is now from non-communicable diseases, but non-communicable disease epidemics that will otherwise increase rapidly in the developing world can be avoided or reversed. Progress of public health in developing countries is possible, but will require sufficient funding and human resources; improved physical plant and information systems; effective programme implementation and regulatory capacity; and, most importantly, political will at the highest levels of government.     

Issues in environmental epidemiological research: the example of environmental lead and health

Modern environmental epidemiology encompasses the "traditional" area of physico-chemical hazards, along with health hazards in the societal environment (e.g. noise, stress, social organisation), and, increasingly, supranational problems (e.g. ozone depletion, global warming). As governments undertake environmental management, improved quantitative estimates of environmental risks to health are needed. Methodological difficulties of environmental epidemiological research include problems of exposure measurement, of estimating exposure at the level of the individual, and of detecting relatively small effects (particularly at low exposure levels). The health hazards of occupational lead exposure are well documented. The health hazards of environmental exposure to lead, within the general population, remain a focus of continuing epidemiological research. Indeed, the reported adverse effects upon the developing central nervous system of young children are now central to public health debate about environmental lead exposure standards. Recent evidence from cohort studies in several countries indicates adverse effects of environmental lead exposure upon early childhood mental development. In South Australia, a cohort study of children born in a lead smelter community, Port Pirie, has revealed evidence of such an effect. After controlling for many potential confounding factors (social, behavioural, family, and medical), cumulative postnatal lead exposure was found to be weakly associated with an adverse effect upon mental development at age two years and, more strongly, at age four years. The relations between environmental epidemiological research and public health policy are discussed.     

Lead exposure in Latin America and the Caribbean. Lead Research Group of the Pan-American Health Organization.

As a result of the rapid industrialization of Latin America and the Caribbean during the second half of this century, exposure to lead has become an increasingly important problem. To obtain an estimate of the magnitude of lead exposure in the region, we carried out a survey and a literature search on potential sources of lead exposure and on blood lead concentrations. Sixteen out of 18 Latin American and 2 out of 10 Caribbean countries responded to the survey. Lead in gasoline remains a major problem, although the lead content has decreased in many countries in the last few years. The impact of leaded fuel is more important in urban settings, given their high vehicular density. Seventy-five percent of the population of the region lives in urban areas, and children younger than 15 years of age, the most susceptible group, comprise 30% of the population. Other sources of lead exposure identified in the region included industrial emissions, battery recycling, paint and varnishes, and contaminated food and water. Lead is recognized as a priority problem by national authorities in 72% of the countries that responded to the survey, and in 50% of the countries some legislation exists to regulate the lead content in certain products. However, compliance is low. There is an urgent need for a broad-based coalition between policy makers, industry, workers, unions, health care providers, and the community to take actions to reduce environmental and occupational lead exposures in all the Latin American and Caribbean countries.     

Lead exposure, interactions and toxicity: food for thought

The recognition that nutritional status plays a role in altering susceptibility to lead absorption and toxicity has triggered the development of this review. There has been a significant increase worldwide in awareness and concern about the effects of lead on human health and the environment over the last two decades. Both occupational and environmental exposures to lead remain a serious problem in many developing and industrialising countries, as well as in some developed countries. Port Pirie (South Australia) has the world's largest lead smelter and the surrounding population continues to be exposed to environmental lead. The increased awareness of the detrimental impacts of 100 years of smelting at Port Pirie led in 1984 to the development of the Lead Implementation Program, run by the Environmental Health Centre (EHC), Department of Human Services (DHS). The major focus of the program is to reduce household lead exposure for pregnant women and children below the age of five years. Despite intervention efforts by all stakeholders in Port Pirie, 55% of children less than 4 years old have blood lead levels above the National Health and Medical Research Council (NH&MRC) goal of 10 microg/dl. The Port Pirie Lead Implementation Program includes components on nutrition education aimed at reducing lead absorption and toxicity. However, nutritional intake and nutritional status of Port Pirie residents, in particular children under five years, has not been evaluated. This review focuses on nutrition as a component of intervention in lead toxicity and it discusses the nutritional concerns in relation to lead exposure. Fortunately most food patterns that reduce susceptibility to lead toxicity are consistent with recommendations for a healthy diet. The relationship between nutritional status and lead uptake and toxicity is most clearly established for irregular food intake (i.e. periods of fasting), marginal calcium ingestion and (subtle) iron deficiency.     

The health impact of environmental pollutants: a special focus on lead exposure in South Africa

Studies have shown blood lead levels of some children in South Africa at levels of health concern. New studies show even relatively low lead levels to have detrimental effects on cognitive function in young children. Large numbers of South African inner-city and other children have been shown to have unacceptably high blood lead levels. Studies indicate that blood lead levels of children living in South Africa's urban areas are higher than those of children in most developed countries, including Great Britain, Europe, and the United States. Although data and reported studies are very sparse, mean blood lead levels of approximately 15 microg/dl have been reported in children. Elevated blood lead levels were associated with socioeconomic status and housing conditions. Key environmental risk factors for elevated blood levels were contaminated soil and dust in the urban environment, and the still large number of automobiles using leaded gasoline. In view of emerging evidence linking lead at increasingly lower levels to adverse effects in children, the South African government is taking actions to reduce lead exposure among vulnerable groups. Currently, South Africa has no national lead surveillance program. The government, therefore, has developed international and regional partnerships to prevent and address the problem of lead exposure.     

Some observations on the communicable diseases as public health problems

Notwithstanding the deficiencies in reporting, an attempt is made in the present study to provide some useful information on the importance of the communicable diseases in the world over the decade 1957-58 to 1967-68. In this period health authorities in the developing countries almost invariably reported communicable diseases as their main public health problems, whereas, in the developed countries, the only communicable diseases still considered as public health problems were tuberculosis, venereal diseases, and hepatitis. In the developing countries nearly half of the principal causes of death were communicable diseases, and in both the developing and developed countries respiratory infections ranked high on the list. Deaths from tuberculosis have come down markedly in the developed countries and to a lesser degree in the developing countries. Infectious diseases of childhood are no longer a problem in the developed countries but are still important in the developing countries. The communicable diseases of importance to the developing countries may be divided into two groups—those requiring long-term development for their solution (e.g., dysentery, typhoid fever, parasitic diseases, and respiratory infections) and those that would respond rapidly to control by such methods as immunization.     

Antioxidant micronutrients and cataract: a review of epidemiological evidence

Cataract is one of the leading causes of blindness among the elderly and an important public health problem worldwide. Life expectancy has increased considerably during this century in both developing and developed countries. Population ageing will lead to increased resources required to treat cataract. Epidemiological studies have suggested that intake of foods containing micronutrients with antioxidant potential may be protective against cataract, but the role of the individual antioxidant micronutrients on the cataract process has not been yet elucidated.Although surgical treatment to remove cataract is very effective, the incidence in developing countries is so high that it will overwhelm the capacity of surgical programs.An increased understanding of the aetiology of cataract may lead to the development of non-surgical strategies to delay o prevent cataract. A preventive approach appears to be essential to the global problems of cataract.     

Can lessons from public health disease surveillance be applied to environmental public health tracking?

Disease surveillance has a century-long tradition in public health, and environmental data have been collected at a national level by the U.S. Environmental Protection Agency for several decades. Recently, the Centers for Disease Control and Prevention announced an initiative to develop a national environmental public health tracking (EPHT) network with "linkage" of existing environmental and chronic disease data as a central goal. On the basis of experience with long-established disease surveillance systems, in this article we suggest how a system capable of linking routinely collected disease and exposure data should be developed, but caution that formal linkage of data is not the only approach required for an effective EPHT program. The primary operational goal of EPHT has to be the "treatment" of the environment to prevent and/or reduce exposures and minimize population risk for developing chronic diseases. Chronic, multifactorial diseases do not lend themselves to data-driven evaluations of intervention strategies, time trends, exposure patterns, or identification of at-risk populations based only on routinely collected surveillance data. Thus, EPHT should be synonymous with a dynamic process requiring regular system updates to a) incorporate new technologies to improve population-level exposure and disease assessment, b) allow public dissemination of new data that become available, c) allow the policy community to address new and emerging exposures and disease "threads," and d) evaluate the effectiveness of EPHT over some appropriate time interval. It will be necessary to weigh the benefits of surveillance against its costs, but the major challenge will be to maintain support for this important new system. Key words: environmental health, evaluation, intervention, registries, surveillance.     

Air pollution and population health: a global challenge

“Air pollution and population health” is one of the most important environmental and public health issues. Economic development, urbanization, energy consumption, transportation/motorization, and rapid population growth are major driving forces of air pollution in large cities, especially in megacities. Air pollution levels in developed countries have been decreasing dramatically in recent decades. However, in developing countries and in countries in transition, air pollution levels are still at relatively high levels, though the levels have been gradually decreasing or have remained stable during rapid economic development. In recent years, several hundred epidemiological studies have emerged showing adverse health effects associated with short-term and long-term exposure to air pollutants. Time-series studies conducted in Asian cities also showed similar health effects on mortality associated with exposure to particulate matter (PM), sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃) to those explored in Europe and North America. The World Health Organization (WHO) published the “WHO Air Quality Guidelines (AQGs), Global Update” in 2006. These updated AQGs provide much stricter guidelines for PM, NO₂, SO₂ and O₃. Considering that current air pollution levels are much higher than the WHO-recommended AQGs, interim targets for these four air pollutants are also recommended for member states, especially for developing countries in setting their country-specific air quality standards. In conclusion, ambient air pollution is a health hazard. It is more important in Asian developing countries within the context of pollution level and population density. Improving air quality has substantial, measurable and important public health benefits.     

World Health Organization global oral health strategies for oral health promotion and disease prevention in the twenty-first century

Despite great improvements in oral health in the past decades, oral disease remains a major public health problem worldwide. The burden of oral disease is particularly high among the disadvantaged population groups in both developing and developed countries. The pattern of oral disease reflects distinct risk profiles across countries that are related to living conditions, lifestyles, environmental factors, and the availability and accessibility of oral health services. In several developing countries, people at large do not benefit from preventive oral health programmes. It is expected that the incidence of dental caries will increase in the near future in many of these countries as a result of growing consumption of sugars and inadequate exposure to fluorides. With the rising use of tobacco in developing countries, the risk of periodontal disease, tooth loss and oral cancer may therefore increase. Several oral diseases are linked to non-communicable chronic diseases or conditions that share common risk factors, such as diabetes, obesity and cancer. Similarly, general diseases often have oral manifestations (e.g. diabetes or HIV/AIDS). Worldwide strengthening of public health programmes through implementation of effective oral disease prevention measures and health promotion is urgently needed, and use of common risk factors approaches should integrate oral health within national health programmes. The challenges to oral health improvement are particularly high in developing countries. The World Health Organization Global Oral Health Programme formulates policies and actions for the improvement of oral health, strategies that are fully integrated with chronic disease prevention and general health promotion. At the 60th World Health Assembly in 2007, the WHO Member States agreed on an action plan for oral health and integrated disease prevention, thereby confirming the approach of the Oral Health Programme. The policy forms the basis for future development of oral health programmes.     

A global approach to childhood lead poisoning prevention

Childhood lead poisoning is an important, preventable environmental disease affecting millions of children around the world. The effects of lead are well known and range from delayed and adversely affected neurodevelopment to severe health outcomes including seizures, coma, and death. This article reviews the childhood effects of lead poisoning, the approach being taken to the problem in the United States, and the obstacles faced by developing nations in dealing with lead exposure. The United States has attacked the childhood lead poisoning problem by attempting to eliminate sources of exposure, including gasoline, solder in water pipes and cans, and industrial emissions. These actions have resulted in a dramatic reduction in the number of children with elevated blood lead levels in the United States over the last two decades. However, many developing countries are just beginning to address the problem. Successful efforts will need to incorporate epidemiologic methods, source identification, enforced regulations, and a long-term government commitment to eliminating lead as a threat to the next generation of children.     

Lowbury Lecture 2008: infection control and limited resources – searching for the best solutions

Healthcare-associated infections constitute an important public health problem in both developing and transitional countries. Despite considerable progress in the development of infection control programmes in some countries with limited resources, programmes in most developing world settings are non-existent, or are not implemented. Kosova, the poorest country in Europe, illustrates the challenges posed by infection control in the developing world. In many hospitals activities are limited by the lack of financial resources, poor infrastructure, overcrowding, inadequate hygiene, poorly functioning laboratory services, poor management, insufficient technology and a shortage of trained staff. Infection control guidelines from developed countries are often perceived as a standard for the developing world, but have to be modified to take into account differences in local needs. The best solutions entail greater governmental commitment and application of infection control procedures consistent with available resources. The International Nosocomial Infection Control Consortium (INICC) plays an important role in these activities in developing countries.     

The role of schools of public health in capacity building

Public health has been an enormously effective instrument for improving life expectancy and quality of life. Historically a sphere of governmental activity led by physicians and staffed by sanitarians and nurses, public health has evolved to become a multi-facetted field of societal activity. It engages many agencies and community action in reducing infectious and non-communicable diseases as well as many aspects of lifestyle and health equity. Education for an adequate professional workforce is one of its key functions. Schools of public health have fulfilled this role only partly even in developed countries, but in countries in transition and in low-income countries the problem is much more acute. We discuss the role of mentoring of new schools calling for strong public and private donor support for this as a key issue in global health.     

Climate Change and Developing-Country Cities: Implications For Environmental Health and Equity

Climate change is an emerging threat to global public health. It is also highly inequitable, as the greatest risks are to the poorest populations, who have contributed least to greenhouse gas (GHG) emissions. The rapid economic development and the concurrent urbanization of poorer countries mean that developing-country cities will be both vulnerable to health hazards from climate change and, simultaneously, an increasing contributor to the problem. We review the specific health vulnerabilities of urban populations in developing countries and highlight the range of large direct health effects of energy policies that are concentrated in urban areas. Common vulnerability factors include coastal location, exposure to the urban heat-island effect, high levels of outdoor and indoor air pollution, high population density, and poor sanitation. There are clear opportunities for simultaneously improving health and cutting GHG emissions most obviously through policies related to transport systems, urban planning, building regulations and household energy supply. These influence some of the largest current global health burdens, including approximately 800,000 annual deaths from ambient urban air pollution, 1.2 million from road-traffic accidents, 1.9 million from physical inactivity, and 1.5 million per year from indoor air pollution. GHG emissions and health protection in developing-country cities are likely to become increasingly prominent in policy development. There is a need for a more active input from the health sector to ensure that development and health policies contribute to a preventive approach to local and global environmental sustainability, urban population health, and health equity.