Chemicals that Cause Health Hazards

There are three main groups of chemicals to consider, with regard to health issues  

Let us begin with a question What is a toxic compound and with several definitions  

Toxicants are certain chemical (or physical) agents that have harmful or adverse effects on living organisms and can seriously damage or disrupt biological functions [5]. 

The word toxic is considered as synonymous with harmful and poisonous , with regard to the effects of these chemicals [6]. However, although toxicity , simply, is the ability of a substance to cause injury to biological tissue , the hazard (or risk) posed by a substance is the probability that this substance can cause injury in a given environment , which is broader in definition. The hazard posed by any substance is characterised by factors such as its toxicity, the details of its absorption and metabolisation as well as excretion, its speed of action, perceptible signs of its possible hazard(s), and its potential (if there is any) for fire or explosion. 

The word toxin refers to a poisonous substance produced by a living organism, e.g., a bacteria. 

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Hazardous Air Pollutants (HAP) airborne chemicals that cause serious health and environmental effects. 

This article outlines the food contact legislation in the UK that applies to plastic articles and materials that come into contact with food. Key requirements are that materials must not transfer chemicals to food in quantities that cause a hazard to human health, or cause the food to become tainted with a strange taste or odour. The regulations also set out testing conditions that enable compliance with the requirements to be demonstrated. 

First, the threshold for hazardous chemicals that cause deterministic effects is assumed for purposes of health protection to represent a lower confidence limit, taking into account uncertainties in the dose-response relationship (see Section 3.2.1.2.7). Depending, for example, on the slope of the dose-response relationship near the threshold, the chosen steps in the dosing regimen, and the magnitude of uncertainties in the data, the lower confidence limit of the assumed threshold can be substantially below MLE. In radiation protection, the estimated thresholds for deterministic effects are based on MLEs of dose-response relationships (ICRP, 1991). 

Stochastic responses from exposure to radionuclides and hazardous chemicals generally are of concern in health protection of the public and in classifying waste. Of the three differences in approaches to dose-response assessment identified above, the most important is the use of a best estimate (MLE) of the dose-response relationship for radionuclides but upper-bound estimates (UCLs) for hazardous chemicals that cause stochastic effects. UCL in the dose-response relationship for chemicals that cause stochastic effects normally exceeds MLE by a factor of 5 to 100 or more. If this difference... 

Hard, G. C., Rodgers, I. S., Baetcke, K. P., Richards, W. L., McGaughy, R. E., and Valcovic, L. R. (1993). Hazard evaluation of chemicals that cause accumulation of alpha 2u-globuUn, hyaUne droplet nephropathy, and tubule neoplasia in the kidneys of male rats. Environ Health Perspect 99, 313-349. 

Chemicals that are released into the environment outside the worksite may cause health hazards to the general public. The released chemicals may react with the ambient oxygen and ozone in the presence of sunlight to form other chemicals such as acids, aldehydes, nitrates and other irritant and/or noxious chemicals. 

To begin with, this book gives information about chemicals that can cause health hazards and toxic compounds , with regard to plastics and rubbers (mainly in Chapters 2, 3 and 10) and also carcinogenic chemicals, for their relevance to the topic. Some specific examples are described in more detail in the other chapters. 

Repeated exposure to minute quantities of hazardous chemicals that cause no acute health effects but may cause chronic health effects is called ... 

Although most of the oil from the lakes has been removed or has been the subject of heavy weathering, the lakebeds still contain a large amount of oil, which cannot be easily removed. Analysis of samples indicated that the composition of the oil in the lakes continues to change [77]. The chemical composition of weathered oil showed a decrease in aromatic compounds, and an increase in resins and higher polycyclic aromatic hydrocarbons. This inaeases the hazard potential of oil lakes. Heavily contaminated soils may eventually erode and be resuspended and transported to populated areas during dust storms and could cause health hazards [35]. There is also the possibility of contaminating soil with heavy metals, particularly nickel, vanadium, chromium, and lead. 

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