The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. Heavy metals have been used by humans for thousands of years. Although several adverse health effects of heavy metals have been known for a long time, exposure to heavy metals continues, and is even increasing in some parts of the world, in particular in less developed countries, though emissions have declined in most developed countries over the last 100 years. Cadmium compounds are currently mainly used in re-chargeable nickel-cadmium batteries. Cadmium emissions have increased dramatically during the 20th century, one reason being that cadmium-containing products are rarely re-cycled, but often dumped together with household waste. Cigarette smoking is a major source of cadmium exposure. In non-smokers, food is the most important source of cadmium exposure. Recent data indicate that adverse health effects of cadmium exposure may occur at lower exposure levels than previously anticipated, primarily in the form of kidney damage but possibly also bone effects and fractures. Many individuals in Europe already exceed these exposure levels and the margin is very narrow for large groups. Therefore, measures should be taken to reduce cadmium exposure in the general population in order to minimize the risk of adverse health effects. The general population is primarily exposed to mercury via food, fish being a major source of methyl mercury exposure, and dental amalgam. The general population does not face a significant health risk from methyl mercury, although certain groups with high fish consumption may attain blood levels associated with a low risk of neurological damage to adults. Since there is a risk to the fetus in particular, pregnant women should avoid a high intake of certain fish, such as shark, swordfish and tuna; fish (such as pike, walleye and bass) taken from polluted fresh waters should especially be avoided. There has been a debate on the safety of dental amalgams and claims have been made that mercury from amalgam may cause a variety of diseases. However, there are no studies so far that have been able to show any associations between amalgam fillings and ill health. The general population is exposed to lead from air and food in roughly equal proportions. During the last century, lead emissions to ambient air have caused considerable pollution, mainly due to lead emissions from petrol. Children are particularly susceptible to lead exposure due to high gastrointestinal uptake and the permeable blood-brain barrier. Blood levels in children should be reduced below the levels so far considered acceptable, recent data indicating that there may be neurotoxic effects of lead at lower levels of exposure than previously anticipated. Although lead in petrol has dramatically decreased over the last decades, thereby reducing environmental exposure, phasing out any remaining uses of lead additives in motor fuels should be encouraged. The use of lead-based paints should be abandoned, and lead should not be used in food containers. In particular, the public should be aware of glazed food containers, which may leach lead into food. Exposure to arsenic is mainly via intake of food and drinking water, food being the most important source in most populations. Long-term exposure to arsenic in drinking-water is mainly related to increased risks of skin cancer, but also some other cancers, as well as other skin lesions such as hyperkeratosis and pigmentation changes. Occupational exposure to arsenic, primarily by inhalation, is causally associated with lung cancer. Clear exposure-response relationships and high risks have been observed.

/pdf/hazards-of-heavy-metal-contamination-ytc24a1l2a.pdf

Hazards of heavy metal contamination.

Arsenic round the world: a review.

Plastics debris in the marine environment, including resin pellets, fragments and microscopic plastic fragments, contain organic contaminants, including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons, petroleum hydrocarbons, organochlorine pesticides (2,2′-bis(p-chlorophenyl)-1,1,1-trichloroethane, hexachlorinated hexanes), polybrominated diphenylethers, alkylphenols and bisphenol A, at concentrations from sub ng g–1 to µg g–1. Some of these compounds are added during plastics manufacture, while others adsorb from the surrounding seawater. Concentrations of hydrophobic contaminants adsorbed on plastics showed distinct spatial variations reflecting global pollution patterns. Model calculations and experimental observations consistently show that polyethylene accumulates more organic contaminants than other plastics such as polypropylene and polyvinyl chloride. Both a mathematical model using equilibrium partitioning and experimental data have demonstrated the transfer of contaminants from plastic to organisms. A feeding experiment indicated that PCBs could transfer from contaminated plastics to streaked shearwater chicks. Plasticizers, other plastics additives and constitutional monomers also present potential threats in terrestrial environments because they can leach from waste disposal sites into groundwater and/or surface waters. Leaching and degradation of plasticizers and polymers are complex phenomena dependent on environmental conditions in the landfill and the chemical properties of each additive. Bisphenol A concentrations in leachates from municipal waste disposal sites in tropical Asia ranged from sub µg l–1 to mg l–1 and were correlated with the level of economic development.

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Transport and release of chemicals from plastics to the environment and to wildlife

Current status of cadmium as an environmental health problem.

This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."

The Toxicology of Mercury and Its Chemical Compounds

https://jcp.bmj.com/content/jclinpath/33/6/608.3.full.pdf

Environmental Health Criteria

the efforts of experts writing on specialist topics and bringing together into a single chapter facets of information that are only briefly mentioned in the more formal textbooks. Six topics are covered in this first volume, of what it is proposed will be a continuing series. These vary from hypothalamic endocrine disease, and cyclic nucleotides in clinicai endocrinology to the mechanisms and management of postural hypotension. The chapters are well written, and bytheir format emphasise the relevance and application of recent scientific developments to diagnosis and therapy. This and further volumes should provide readily availablereferencematerial for workers in particular fields of research although because of their format they will be of limited interest to many workers in the endocrinological field.

https://jcp.bmj.com/content/jclinpath/35/1/121.2.full.pdf

Microenvironments in Haemopoietic and Lymphoid Differentiation

For a reviewer to procrastinate over an opinion on any book referred to him is inexcusable, above all in the eyes of the editor. Critics of readable novels should seldom be daunted. By contrast when it comes to forming an opinion about a toxicological monograph like this one on Arsenic it is well-nigh impossible to sit back and read from page I to page 174 and still retain one's alertness and sense of judgement. Instead, appraisal on behalf of others is possible only by keeping the book beside one as a constant source of reference and seeing how it fares in this capacity. On this count the present volume, issued as one among a series of Environmental Health Criteria by the World Health Organisation, is to be strongly recommended. It serves as an invaluable collection of relevant facts within a conveniently small compass. Indeed, if there is any quibble at all, it is to question whether there is any reason for adopting in it the prose style at all. A series of Tables and diagrams might have served the purpose equally well. At all events, for anyone faced with a problem of poisoning from arsenic, this is the text to which he can always profitably turn in the first instance-as indeed are others in this series for their respective topics. ROY GOULDING

https://jcp.bmj.com/content/jclinpath/37/1/106.3.full.pdf

Intercellular Communication in Leucocyte Function

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Abdominal Ultrasound. Static and Dynamic Scanning

https://jcp.bmj.com/content/jclinpath/35/1/123.3.full.pdf

Hem Kay

Papers

Environmental Health Criteria

Microenvironments in Haemopoietic and Lymphoid Differentiation

Intercellular Communication in Leucocyte Function

Abdominal Ultrasound. Static and Dynamic Scanning

Apheresis: Development, Applications, and Collection Procedures