International resources in occupational toxicology

The European Community 'REACH' regulation which deals with the Registration, Evaluation, Authorisation and Restriction of Chemical substances (EC 2006) came into force on 1 June 2007. REACH legislation requires manufacturers and importers of chemicals within Europe to submit technical information on the properties of their substances, which will allow their safe handling, and to register the information in a central database run by the European Chemicals Agency (ECHA) in Helsinki. The American...

Free radical hypothesis

Free radicals are generated continuously by oxidative metabolic processes. Free radicals are highly reactive and dangerous they can react with lipids and trigger the chain reactions of lipid peroxidation. Inflammatory responses follow, with the synthesis and release of a welter of mediators (Kelly and Mudway 2007) Such effects are guarded against by antioxidants, including reduced glutathione, uric acid, and ascorbic acid. These compounds are secreted into the airway lining fluid. Particles...

Health effects of chronic arsenic exposure

Arsenic is widely distributed throughout the Earth's crust. It can be released into the atmosphere by a range of natural processes, such as volcanic activity, or human activities, such as mining, metal smelting, and mobilization into drinking water from geological deposits as a result of drilling wells (World Health Organization 2010). Inorganic arsenic is naturally present at high levels in the groundwater of several countries, including China, India and Bangladesh, Argentina, Chile, and the...

Binding of carbon monoxide to haemoglobin

Haemoglobin, found in red blood cells, carries oxygen to all cells in the body for the cells to be metabolically active and survive. CO has an affinity for haemoglobin that is 200-250 times more than that of oxygen, thus in the presence of CO haemoglobin competes and preferentially binds to CO, forming carboxyhaemoglobin (COHb). CO remains bound to haemoglobin for a longer period than oxygen, accumulating in blood and preventing oxygen from reaching binding sites. Haemoglobin has four oxygen...

A11 The immune system

Immunology is the study of the physiological responses by which the body destroys or neutralizes foreign matter or xenobiotics, living and non-living, as well as its own cells that have become altered in certain ways. The ability of the immune response to protect us against bacteria, fungi, viruses and other parasites, and other foreign matter is one of the most important defence mechanisms of the human body. This immune response the process by which xenobiotics are destroyed or neutralized is...

Sources of carbon monoxide

When there is insufficient oxygen for organic compounds to burn efficiently, there is production of CO. If there is enough oxygen for complete combustion, carbon dioxide (CO2) is formed. The most common source of CO poisoning in the home is from faulty or improperly installed heating or cooking appliances, where either insufficient oxygen leads to the production of CO or CO is not properly removed, such as a defect in a flue or ventilation system. A common misconception is that CO is only...

David Baker

At the end of this chapter and any recommended reading the student should be able to 1. explain the normal structure and function of the human body systems, and the concept of target organs and systems 2. explain, with the use of examples, how dysfunction in each of the important body systems may occur following exposure to toxic agents 3. describe and discuss the manifestations of dysfunction in each of the important systems of the human body 4. demonstrate awareness of the common chemicals...

Organic irritants

The combustion of organic compounds also results in the formation of organic irritant products in the fire effluent. The incomplete combustion or pyrolysis of materials including wood, fossil fuels, synthetic and natural polymers, and foodstuffs gives rise to a range of aldehydes (International Programme on Chemical Safety 1991). Of this group, acrolein and formaldehyde are the best known, although it is highly unlikely that these will be the sole organic irritants present in fire smoke, which...

Gaseous air pollutants

Ozone is a classic secondary air pollutant there are no significant outdoor and few indoor sources of ozone. It is important to distinguish between the ozone of the stratosphere, which protects against UV radiation and which is depleted by halogenated compounds, and the ozone of the troposphere, which affects health. The ozone of the troposphere comes largely from a series of photochemical (light-driven) reactions that depend on three things light, oxides of nitrogen, and organic compounds....

Health Issues for vulnerable groups

The individuals who are most at risk from exposure to combustion products are those who have pre-existing respiratory diseases, such as asthma or chronic obstructive pulmonary disease. The presence of an existing respiratory condition increases the susceptibility of the individual to the adverse effects of exposure to asphyxiant gases such as CO (International Programme on Chemical Safety 1999). Acute exposure to smoke containing mixtures of asphyxiant and irritant gases is therefore likely to...

Vinyl chloride exposure and health effects

Vinyl chloride (Figure 8.2), which is produced for industrial use as a chemical intermediate in the manufacture of other compounds, particularly polyvinyl chloride (PVC), is toxic by all routes of exposure. It is metabolized to the active metabolites chloroethylene oxide and chloracetaldehyde, which is responsible for its toxicity. In the absence of proper controls, acute exposure will produce immediate signs and symptoms, such as respiratory irritation, producing coughing, wheezing, and...

Box 122 Food additives

Food additives have a technological function in food. Important subcategories are flavour enhancers and flavourings emulsifiers, stabilizers, gelling agents, and thickeners. Fig. 12.1 Derivation of an acceptable or tolerable daily intake. Fig. 12.1 Derivation of an acceptable or tolerable daily intake. identified (the NOAEL). The NOAEL is divided by uncertainty factors (or safety factors) to allow for interspecies differences if the NOAEL is derived from a study in laboratory animals, and for...

Inorganic acid gases

The most common inorganic acid gases evolved during combustion include the halogen acids (HCl, HF, HBr) and oxides of sulphur, nitrogen, and phosphorus (Department of Health 1996). Production of these gases will be dependent on the chemical composition of the materials involved. Hydrogen chloride Hydrogen chloride (HCl) is the most important halogen acid gas likely to be evolved during combustion (Hartzell 1996). Because of the chlorine content of many commonly used materials, including...

During breastfeeding

As a general rule, breast-feeding mothers should avoid 1. remedies containing high doses of herbs containing alkaloids, particularly those that may affect the nervous system, e.g. the Chinese herbs coptis, philodendron (berberine alkaloids), sophora root (oxymantrine), ma-huang (ephedrine), and evodia (rutecarpine) 2. remedies containing high doses of herbs known to have hormonal effects, e.g. fennel, anise, liquorice 3. herbs containing plant alkaloids known to cause liver and or kidney...