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Rhodium [Rh, 45]
The environmental concentration of Rh is slowly increasing as a result of using
PGMs in automobile catalytic converters. Because finely dispersed Rh particles from
exhaust converters become bioavailable by some alimentary chains or metabolic
pathways, and toxic effects are expected. The main pathways by which Rh can enter
the food chain is aerosol deposition, caused by Rh emission from motor vehicles and
industrial sources. The primary sources from which Rh can be incorporated into the
human body are therefore plants or agricultural products. This explains the increasing interest in quantifying Rh in real matrices of alimentary concern (Sánchez Rojas
et al. 2007). Rhodium content in foodstuffs is very low, in general not exceeding
1 μg/kg (Table 38.1).
The dietary exposure of population to Rh in the United Kingdom has been estimated to be 0.3 μg/day in 1999 (Ysart et al. 1999) and <2.3 μg/day in 2006 (Rose
et al. 2010).