Environmental exposure prevalence

Genetic factors cannot explain the recent rapid rise in asthma prevalence. Asthma appears to require both genetic predisposition and environmental exposure. Many patients with occupational asthma develop the disease late in life upon exposure to specific allergens in the workplace. Environmental influences in utero or in infancy may contribute to the development of asthma. Maternal smoking during pregnancy or exposure to secondhand smoke after birth increases the risk of childhood asthma.3 Adult-onset asthma is not uncommon and may be related to atopy, nasal polyps, aspirin sensitivity, occupational exposure, or a recurrence of childhood asthma. 

Information on health effects in animals is extensive and available for all effect categories, but is nearly completely limited to oral exposure studies, which appears to reflect experimental practicality and concern for what is thought to be the most prevalent and likely route of environmental exposure. 

The influence of such variables as age, sex, smoking, ethanol, oral antifertility agents, total calories, the relative proportion of the macromolecular constitutents of the diet, exercise, and environmental exposure to certain prevalent chemicals would eventually need to be recognized and to some extent tested before the generality of any conclusions drawn in one group of subjects could be extended to other groups. Also, as previously emphasized, normal subjects under... 

Our inability to defend ourselves against new chemicals and mixtures often results in epidemics of disease. For example, asthma, autism, infertility, and many cancers affect different parts of the body and seemingly have different etiologies. All, however, can be related to a combination of genetic predisposition and environmental exposure to chemicals. All are less prevalent where chemical exposures are lower, for example, in rural areas. All have known single chemical exposure causes and they can all be related to low level exposure to chemical mixtures. The toxic effects of chemical mixtures are explored in the chapters that follow. 

Autism certainly has a genetic factor associated with it. Studies, however, showing seasonal and annual variations in its prevalence, increased prevalence in urban versus rural areas, increased prevalence in areas with increased environmental pollution, and increased prevalence in offspring of mothers who have taken certain drugs, leads to the conclusion that there is a connection between maternal environmental exposure to neurotoxic chemicals and the prevalence of autism. 

Asthma is the most prevalent chronic disease affecting children worldwide and its prevalence has tripled in the last 30 years. Though a genetic predisposition is generally believed essential for asthma to ensue, environmental exposures to immunotoxins have been demonstrated to play a role in the induction of asthma. Two studies have shown that children exposed to environmental tobacco smoke (ETS) have increased incidences of asthma. Young children (aged 2 months to 5 years) who are exposed to ETS are more than twice as likely to be sensitized and develop asthma than their cohorts who are not so exposed. I38,39 ... 

Some effects of mixtures may become predictable, particularly in simple binary mixtures. For example carbon tetrachloride reacts synergistically with both ethanol and isopropanol as a liver toxin. Predictability is less reliable in complex mixtures that are prevalent in most environmental exposures. ... 

Studies of autoantibodies in the general population allow us to determine the prevalence of specific autoantibodies among people who do not have a clinically evident autoimmune disease, whether the prevalence of autoantibodies reflects the demographic variation in disease risk and whether specific environmental exposures are related to the expression of specific autoantibodies. These studies are most feasible for the autoantibodies associated with the most common autoimmune diseases diabetes mellitus type 1, autoimmune thyroid disease, and rheumatoid arthritis. Important issues with respect to interpreting these types of studies include the type of test used and definition of a positive result. 

The bond between the FRP and concrete has been characterized by using a variety of experimental techniques and a number of studies have been conducted to assess the effects of defects in the substrate, FRP, and the interface as well as environmental conditions prevalent during the application of the FRP. A number of studies have also been conducted using flexural specimens or peel-type tests to assess the effect of environmental exposure on the performance of the rehabilitated beams and fracture toughness, respectively. While these provide useful information regarding the effects of environmental exposure, they do not focus on the critical region of the bond between the concrete and FRP at a level that can be directly of use to the designer or used for field assessment of durability. 

Risk factors for the development of AML include exposure to environmental toxins, Hispanic ethnicity, and genetics.6 Of greater concern is the increased prevalence of AML as a secondary malignancy, resulting from chemotherapy and radiation treatment for other cancers. Alkylating agents, such as ifosfamide and cyclophosphamide, and topoisomerase inhibitors, such as etoposide, are linked to an increased risk of myelodysplastic syndrome (MDS) and AML.8... 

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