If little or no exposure to this chemical occurs, or is likely to occur, risk of harm may be negligible. Determining exposure is a challenge for chemists and may require development of new techniques. For example, guidelines for exposure to elements other than carbon are largely set in relation to total elemental concentration. Chemical speciation is ignored at least partly because analytical chemists often do not speciate elemental analysis. For example, arsenic analysis is rarely quoted as arsenite, arsenate, or organic species, although we know that their toxicology is different.
Risk assessment based on total arsenic analysis is meaningless.
Other unifying concerns were related to differential susceptibility to the effects of chemicals owing to genetic and environmental differences and the problem of assessing mixed exposures. The effects of diet were given due attention. Ecotoxicology got less attention than it deserves, and the organizers of the next congress of this kind may wish to include more on this area. The workshop on educational needs for developing countries was particularly interesting. It also appears that there is a lack of expertise in certain specialist areas and that the international organizations should identify these areas in order to help provide necessary course material.