Element concentrations toxic to plants, animals, and man

Abstract

Much has been written on the toxicities of some elements such as lead, mercury, and selenium, and our chief task with these elements was that of selecting the most useful reports to include. For some other elements, reports of toxicities are few and often in obscure publications. The elements selected for this discussion are those that may be environmentally important and especially those for which we have quantitative data. Some of the information in this outline is from unpublished data in our files; most statements, however, are identified by reference citations. The elements are presented alphabetically by their common English names. We have divided the notes on each element into three parts plants, animals, and man and classified associated toxicities under natural and man-induced conditions, where appropriate. References to the toxicities of a few elements of possible environmental concern are inadequate for an evaluation to be made of their hazard. These elements are grouped near the end of this report, and a general discussion is given of the available information on each element. Concentrations of elements generally are presented as parts per million (ppm), although other methods of expressing concentrations may be quoted. In some instances units such as mg/kg of body weight, jumoles/L, ju,g/m3, parts per billion (ppb), or percent provide a clearer concept for a given example, and converting them to ppm was considered to be unnecessary. A part per million is 10~4 percent and a part per billion is 10~7 percent. It will be noted in this report that many of the elements are essential for plants or animals, yet are toxic under certain conditions (Wallace, Romney, Alexander, and Kinnear, 1977). The toxicity of an element depends, first of all, on its chemical form. For example, chlorine in the elemental form (a gas) is highly toxic, whereas chlorine compounds may be relatively harmless, as is sodium chloride (common salt). Conversely, elemental arsenic is not toxic, although some arsenical compounds are highly toxic. Many reports do not specify the chemical form of an element when discussing its toxicity. It can be assumed for most of these reports that, under the specified natural or experimental conditions, the element existed in an undetermined compound and that only the total concentration of the element was known. For most reports in which the basis for expressing concentrations of an element in plant or animal tissues is not specified, a dry-weight basis can be assumed. The toxicity of a substance is also determined by the dosage that is, the amount (in relation to body weight or to the growth medium) and the frequency and duration of administering the substance to the organism. The duration of specified dosages of toxic elements was not given by some investigators, including Bowen in table 7.4 of his 1966

Land Suitability Mapping Using Geochemical and Spatial Analysis Methods

“…Moreover, cigarette smoke is considered an important source of Cd exposure [43]. Cadmium tends to accumulate in humans' liver and kidney [46,80]. Human exposure to Cd compounds may pose a serious health risk [81,82].…”

“…Land use requirements are described, among others, by the absence of a toxic level of elements in the soil. Many plants, vegetables and fruit trees can absorb Cd and Co as they are grown in contaminated soil [44][45][46]. Consuming plants, vegetables or fruits grown in contaminated soil may pose a risk for human health.…”