<Tr> <Td> 24 </Td> <Td> Chromium </Td> <Td> 6992240000000000000 ♠ 24 × 10 </Td> <Td> 0.000014 </Td> <Td> 6992890000000000000 ♠ 8.9 × 10 </Td> <Td> Yes </Td> <Td> </Td> <Td> 6 </Td> </Tr> <Tr> <Td> 25 </Td> <Td> Manganese </Td> <Td> 6993170000000000000 ♠ 170 × 10 </Td> <Td> 0.000012 </Td> <Td> 0.0000015 </Td> <Td> Yes (e.g. Mn - SOD) </Td> <Td> </Td> <Td> 7 </Td> </Tr> <Tr> <Td> 33 </Td> <Td> Arsenic </Td> <Td> 6993260000000000000 ♠ 260 × 10 </Td> <Td> 0.000007 </Td> <Td> 6992890000000000000 ♠ 8.9 × 10 </Td> <Td> Possibly </Td> <Td> toxic in higher amounts </Td> <Td> 15 </Td> </Tr> <Tr> <Td> </Td> <Td> Lithium </Td> <Td> 6992310000000000000 ♠ 31 × 10 </Td> <Td> 0.000007 </Td> <Td> 0.0000015 </Td> <Td> Yes (intercorrelated with the functions of several enzymes, hormones and vitamins) </Td> <Td> toxic in higher amounts </Td> <Td> </Td> </Tr>

Where do most hydrogen ions in the body come from