Effects in Plants, Animals and Humans

The recognition in the early part of the twentieth century that certain mineral elements in small concentrations had observable effects on plant, animal and human well-being has led a host of investigators to try to measure these effects quantitatively. 

The chemical control of insect pests dates back thousands of years. The earliest insecticides were inorganic compounds of copper, lead, and arsenic, as well as some naturally occurring organic compounds such as nicotine (Fig. 7.30a). Few of these first-generation insecticides are in use today because of their adverse side effects on plants, animals, and humans. 

Due to the wide distribution of PGM among different environmental matrices, and also due to their biological availability, several studies have been conducted to obtain information on the uptake and accumulation of PGM in the biosphere. Some investigations have also been made into the metabolism of PGM in plants, animals, and humans. However, due to the fact that the metabolism of PGM is often directly connected with mechanisms affecting their adverse effects, certain aspects of this subject have been dealt with in Part I, Chapter 6. 

Effects on Plants, Animals, and Humans Tab. 22.1 No rmal thallium concentrations in human body fluids and tissue... 

Sources, Production, Important Compounds, Uses, Waste Products and Recycling, 4) Distribution in the Environment, in Foods and Living Orgamsms, 5) Uptake, Absorption, Transport and Distribution, Metabolism and Elimination in Plants, Animals and Humans, 6) Effects (beneficial and/or adverse) on Plants, Animals and Humans, 7) Hazard Evaluation and Limiting Concentrations, 8) Complete References using the Harvard (Name and Date) System. The reference citation system, regrettably not continuously found in the 1st edition, has been, as far as possible, followed in this edition for the benefit of our readers. 

Excess selenium intake can occur in both animals and humans living in areas with elevated selenium in the soil. Most grass and grains do not accumulate selenium, but when an animal consumes plants that do accumulate selenium (some up to 10,000 mg/kg) they can develop a condition called the blind staggers . Symptoms include depressed appetite, impaired vision, and staggering in circles and can ultimately lead to paralysis and death. Humans are susceptible to similar effects as well as additional neurological effects. Selenium deficiency results in heart disorders, skeletal muscle effects, and liver damage. 

Though one can consider the effect of CO2 increase on individual plants, animals and human beings, it is next to impossible to say anything meaningful about the effect on entire ecosystems. This is because it is hard to express in functional terms the present relations between ecosystem composition, function and dynamics and either CO2 levels or the existing climate. By pure chance I happened to be present when Tansley first used the term ecosystem . In the ensuing half-century I have seen it become a household word, and the central notion in the theory of the... 

Yttrium is a non-essential element for microorganisms, plants, animals, and humans. However, no adverse effects of yttrium have been reported on plants and microorganisms, nor has any mechanism of yttrium detoxification in mammals been identified (Luckey and Venugopal 1978 Deuber and Heim 1991). 

---