The Elements in the Second Rank
Summary and Conclusions
For many years, heavy metals such as cadmium, lead and mercury have been known for their potential to cause serious negative effects on humans and the environment. Therefore, gradually, certain restrictions on the use of these metals have been imposed nationally and internationally, and limit values and quality criteria have been established to reduce emissions and discharges into the environment.
A result of restrictions on use can be that the most critical heavy metals become substituted by other elements that are assessed to be less toxic to humans or harmful to the environment. The substitution of cadmium with lithium in batteries can be mentioned as an example of this. Also a number of more exotic metals and metalloids, e.g. gallium and indium, are being introduced for a variety of applications and used in increasing quantities, often without any detailed beforehand knowledge or assessment of their possible adverse effect on health or environmental.
These "new" elements are within the framework of this project termed the "elements in the second rank" (whereas the traditional heavy metals are the "elements in the front rank").
The objective of the study was to collect, analyse and present the present knowledge of 11 selected "second rank" elements with regard to use pattern and consumption in Denmark, dispersal into and behaviour in the environment, hazards to human health and potential effects in the environment, primarily aquatic systems. The 11 elements were antimony, beryllium, bismuth, boron, gallium, indium, lithium, molybdenum, palladium, platinum and vanadium.
Due to the scarcity of data on the occurrence of the selected elements in environmental matrices, not least the waste streams of modern society, a limited programme of chemical analyses was conducted, which comprised municipal wastewater and sewage sludge, stack gas from municipal waste incineration (MSW), leachate from sanitary landfills and from depots for residual products from MSW incineration, and compost from household and garden biowaste.
The outcome of the study can briefly be summarised as follows:
Use pattern and consumption
The application areas of the second rank elements span over a wide range of functionalities and products. Many of the elements are used in modern electronic products including computers and telecommunication equipment and in alloys where the content can be limited to a few percent or even less.
Fossil fuels, in particular coal, contain low concentrations of most of the elements. The total quantity can, however, for some elements be considerable (depending on origin and quality of the coal) or even dominating; i.e. for vanadium up to about 400 tonnes out of a total of approx. 500 tonnes based on the present annual consumption of coal in Denmark.
The consumption of the second rank elements for other purposes than fossil fuel based energy production is estimated to be higher than 10 tonnes per year for antimony, bismuth, boron, lithium, molybdenum and vanadium, whereas the consumption of gallium and indium is less than 1 tonne per year. The yearly consumption of beryllium, palladium and platinum is estimated to be in the range 1-10 tonnes.
Effects on human health and the environment
Based on the available data, the following conclusions are drawn:
 | Antimony, beryllium, boron, molybdenum, platinum and vanadium are classified as dangerous to humans and/or the environment, primarily based on experience related to occupational exposure; |
| Antimony, beryllium and vanadium can have serious long term effects (carcinogenicity, mutagenicity or effects on reproduction); |
| Antimony, bismuth, boron, palladium and platinum can cause sensitization; |
| A number of compounds of antimony, beryllium, bismuth, palladium and platinum are highly toxic to aquatic organisms; |
| The consumption and use of most of the second rank elements are increasing, but for the elements beryllium, gallium, indium, palladium and platinum the present use is still very limited and, consequently, the general risk of exposure is considered low at present; |
| Boron and lithium are, at the present level and pattern of use, not believed to cause significant effects on human health or the environment; |
| If the inherent toxicity and environmental toxicity of the elements are combined with consumption, use pattern and risk of dispersal into the environment, antimony and vanadium are assessed to be the most critical among the second rank elements at present. |
Available data
The available data on the properties and use of the second rank elements are generally limited and insufficient to draw firm conclusions regarding possible impacts on humans or the environment. In particular, the data on long term health effects of beryllium, boron, gallium, indium, lithium, molybdenum, platinum and vanadium are rather sparse. The data on environmental properties of gallium, indium, palladium, platinum and vanadium are very incomplete.