Hypothetical Thresholds for Effects of Platinum Group Elements

Abstract

The platinum-group elements are rhodium, ruthenium, palladium, osmium, iridium, and platinum. Together with rhenium and gold they form the highly siderophilic (“iron-loving”) elements. These are poorly known with respect to toxicity and ecotoxicity. 
 
 The mobilization by man of the eight metals is about 100 times to 1 million times the natural mobilization. Mean soil concentrations in Europe may now be more than doubled for gold, rhenium and rhodium. The objective of the current work was to enable a preliminary assessment of the consequences of such high environmental levels. 
 
 Thresholds for ecological effects found in the literature were divided by the element’s mean soil concentration and plotted against group and period in the periodic system. Thresholds for health effects were correspondingly divided by the mean dietary intake of the element over large population groups. 
 
 For health effects, an upper limit of intake is commonly used. This was shown to be about 4 times the mean normal intake for most period 4 elements. For other periods, occupational exposure thresholds entail upper limits of intake in µg/day of: Ru 18, Rh 8, Pd 17, Re 60, Os 15, Ir 4, Pt 20 and Au 160.
 
 For ecological effects, the no effect thresholds for period 4 were 1-5 times the soil concentrations. Very scarce data suggest higher relative thresholds for periods 5 and 6. 
 
 The current high contaminations of European soil by Rh and possibly Pd may be of concern. Since the estimates of risks are uncertain, further research is warranted.

Hypothetical Soil Thresholds for Biological Effects of Rare Earth Elements

“…For Sc in period 4 and Y in period 5, the threshold of 1125 mg/kg corresponds to 112 and 56 times the natural concentrations (taken from Table A1.1, Section A1.6). This is in line with the high ratios of upper limits of intake to dietary intakes at groups 4-6 of Bengtsson (2019).…”

“…Thresholds for effects of natural elements on soil organisms are closely related to natural soil concentrations for elements in groups 5-12 of period 4, and some systematic dependence also appears to exist for periods 5 and 6 (Bengtsson, 2019). It is of interest to explore if similar relations might hold also for the rare earth elements in period 3, groups 4 (Sc), 5 (Y), and 6 (lanthanides).…”

“…It has also been shown that thresholds for effects on soil organisms for many metals have been set at about 1-5 times the soil concentration for elements in period 4 of the periodic system (Bengtsson, 2019). For 3 elements in period 5, the thresholds were at about 10-20 times the natural concentration.…”

“…With these circumstances taken together, there is a possibility that lanthanide excess concentrations may be up to twice the estimate by Bengtsson 2018, or about 3% as a mean for European soils. Large areas may be exposed to 10 times the mean level (Bengtsson, 2019), that is, up to 30%. This is still not inconsistent with the estimate derived from topsoil/subsoil concentrations.…”

Mikroekstraksiyon Yöntemi ile Su Numunelerinde Paladyumun Spektrofotometrik Tayini

“…Bunun ötesinde, kükürt bağlama özelliğinden dolayı paladyum, DNA, RNA, B6 vitamini ve kazein gibi kükürt içeren biyomoleküllerle koordine olabilir. Sonuç olarak, PdCl2 ve Pd(CH3COO)2 gibi paladyum bileşiklerinin aşırı alımı; astım, saç dökülmesi, mide bulantısı, kardiyovasküler ve hatta kanser gibi birçok ciddi sağlık sorununa neden olabilir (Crosera ve ark., 2018;Chen ve ark., 2018;Bengtsson, 2019). Bu nedenle, çevresel ve biyolojik sistemlerde paladyum miktarınının belirlenmesi büyük önem taşımaktadır.…”