Public health problem

Very little is known of the epidemiology of waterborne diseases. The current database is insufficient to determine the scope and intensity of the problem. The devastating effect of epidemics is sufficient to rank water-associated epidemics as a most important public health problem. 

HBV infection remains a major worldwide public health problem. The World Health Organization estimates that there are still 350 million chronic carriers of the vims, who are at risk of developing chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The success of IFN-a treatment - mainly performed as combined treatment with adenine-arabinoside - has been measured by the normalization of liver enzymes, loss of HBe antigen and of detectable viral DNA in the serum of patients. It has been estimated from several clinical trials that as many as 40% of treated HBV patients would respond to therapy with IFN-a or combined treatment with nucleoside analogues and IFN-a. 

Malaria remains a major public health problem in many parts of the world, including Southeast Asia, sub-Saharan Africa and Latin America where an estimated 300-500 million people are infected. 1-3 million die of malaria every year. The etiologic agents of malaria are protozoan parasites of the genus Plasmodium. Of the four pathogens that can cause malaria in humans (Plasmodium falciparum, P. vivax, P. ovale,... 

Despite the use of 2.5 million tons of pesticide worldwide, approximately 35% of potential crop production is lost to pests. An additional 20% is lost to pests that attack the food post-harvest. Thus, nearly one-half of all potential world food supply is lost to pests despite human efforts to prevent this loss. Pesticides, in addition to saving about 10% of world food supply, cause serious environmental and public health problems. These problems include human pesticide poisonings fish and bird kills destruction of beneficial natural enemies pesticide resistance contamination of food and water with pesticide residues and inadvertent destruction of some crops. 

One reason for the rapid growth in the use of pesticides worldwide has been the "Green Revolution" (5), Although there have been some benefits from pesticide use in agriculture, they also cause significant environmental and public health problems. The same is true in public health where Insecticides have been used to control malaria. However, today Increased resistance to insecticides in mosquitoes and Increased resistance to drugs by the malarial parasite are resulting in an explosive increase of malaria worldwide (5). 

From this analysis it is clear that in addition to their benefits, the use of pesticides in food production not only causes serious public health problems but also considerable damage to vital agricultural and natural ecosystems in the United States and world. A conservative estimate suggests that the environmental and social costs of pesticide use in the United States total about 4 billion each year. Worldwide the yearly environmental and public health costs are probably at least 100 billion. This is several times the 18 bllllon/yr spent on pesticides in the world. 

Vitamin A Deficiency Is a Major Public Health Problem Worldwide... 

An inadequate intake in the diet of those food chemicals that are essential nutrients results in health risks. Indeed these risks are by far the most important in terms of the world s population where malnutrition is a major public health problem. But, unlike the toxic chemicals, they would show a very different dose-response if they were subject to similar animal bioassays. At very low doses there would be a high risk of disease that would decrease as the dose was increased, the curve would then plateau until exposure was at such a level that toxicity could occur. Figure 11.2 shows this relationship which is U- or J-shaped rather than the essentially linear dose-response that is assumed for chemicals that are only toxic. The plateau region reflects what is commonly regarded as the homeostatic region where the cell is able to maintain its function and any excess nutrient is excreted, or mechanisms are induced that are completely reversible. 

Williams, D.R.R (1991). Public health problems of diabetes and its cost to the community. In Textbook of Diabetes (eds G. Williams, J.C. Pickup) pp. 30-34. Blackwell Scientific Publications, London. 

Phencyclidine (PCP) abuse remains a serious public health problem in large urban areas of the United States, with recent trends suggesting increased use after a period of decline (Crider, this volume). Most clinical and research attention has focused on the psychiatric and medical manifestations of acute or subacute PCP intoxication, especially the organic mental disorders (toxic delirium, psychosis, or depression) that PCP can induce (McCarron et al. 1981 McCarron, this volume Sioris and Krenzelok 1978). 

Osteoporosis is an age-related disorder estimated to affect twice as many women as men.1 Characterized by loss of bone mass over a lifetime, it accounts for more than one million fractures annually with one of every five American women over 65 years old having one or more fractured bones.2 3 With the elderly projected to represent 25% of the population by 2030, the consequences of bone loss are a significant public health problem. 

Airborne poisons in the nuclear weapons progam were not limited to radioactive materials released from weapons. The weapons technology involved the use of many exotic materials, some of which were toxic (e.g., beryllium). Hazardous releases of these materials occurred in industrial settings in urban areas and were studied by the Atomic Energy Commission as occupational and public health problems. 

The objectives of this study are to determine the frequency distribution of radon levels in residential structures on a nationwide basis and to investigate factors which affect these levels. This study is needed to obtain a more accurate estimate of the average radon level in homes and to provide reliable data on the number of homes exceeding various radon levels. Such information will provide a better understanding of the magnitude of the public health problem associated with indoor radon levels. In addition this information will establish the base line level against which results of other surveys and indoor radon measurements can be compared. 

Tuberculosis remains a major global public health problem. The World Health Organization estimates that there are 8 million new cases of tuberculosis and 3 million deaths directly attributable to tuberculosis each year [22], Drug resistance is a serious problem worldwide. In a study in New York City, 33% of patients with tuberculosis were infected by organisms resistant to at least one antituberculosis drug, and 19% were infected by organisms resistant... 

Vitamin A deficiency affects more than 100 million children around the world (Miller and others 2002) and thus remains an important public health problem in many countries. Vitamin A is essential for vision, reproduction, growth, immune function, and general health of humans (van Lieshout and others 2001). The major sources of vitamin A in the human diet are retinyl esters (preformed vitamin A) found in foods of animal origin and provitamin A carotenoids from fruits and vegetables. Unfortunately, foods containing preformed vitamin A (meat, milk, eggs, etc.) are frequently too expensive for some economically deprived developing countries, and therefore dietary carotenoids are the main source of vitamin A in these countries. 

Osteoporosis is currently defined as a skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. Bone strength reflects the integration of two main features bone density and bone quality (NIH Consensus 2001). Thus, osteoporosis is a debilitating condition of the skeleton that propends to fractures and is associated with advanced age. The disease has a high prevalence in western countries, as it is a condition associated with advanced age, and it is on the rise since fife expectancy has risen dramatically in the last several decades. It is, therefore, a major public health problem because it not only induces morbidity (fractures and chronic sequelae) with a substantial impact on health-related quality of life, but is also associated with increased mortality (Badia et al. 2001, 2004). 

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