Letter to the editor



I have been leading the zinc industry's scientific input to the European Union (EU) risk assessment for zinc and zinc compounds since it commenced in 1995. I am extremely surprised and disturbed at the premature publication by your journal (Bodar et al. 2005) of the preliminary results and conclusions of a draft risk assessment on zinc that remains under consideration within Europe. This risk assessment is not yet agreed at European level and there are significant dangers in premature disclosure of a draft risk assessment. The paper contains information that is incorrect, outdated, and misleading to the reader.

To illustrate my concerns, I would like to draw attention to the following:

  • The abstract incorrectly states that the assessment concluded that a regional risk was drawn for agricultural soils. This statement is in conflict with the conclusion now reached in the EU (no risk) and is indeed inconsistent with the content of the paper itself.

  • The quantitative assessment of the contribution of sources of zinc to the aquatic environment ignores the main source of emissions, that is, the zinc inputs to water resulting from the lateral leaching of zinc from soil. Although this input is mentioned in the text, it is not integrated into the percentages given for other sources. Consequently, all the figures on relative contribution of sources are highly misleading.

  • Regarding the crucial point of predicted no effect concentration (PNEC) setting, the article fails to make reference to a highly relevant paper by Van Sprang et al. (2004), in which a different PNEC for water was derived with the use of basically the same ecotoxicity data. Key aspects of the PNEC setting, discussed in that paper, such as the use of the best-fit distribution (Van Sprang et al. 2004) versus the use of a default distribution (Bodar et al. 2005), are ignored.

  • Regarding the PNEC sediment, new toxicity data have been generated (as suggested in the paper) that considerably reduce uncertainty surrounding the previous data set used by the Rapporteur and strengthens the weight of evidence for a PNEC sediment that is several times higher than that cited in the paper. Thus, all predicted environmental concentration (PEC)/PNEC ratios mentioned in Table 5 of the paper are outdated.

The points set out above are but 4 examples of statements in the paper that mislead the reader. There will, no doubt, be an opportunity to discuss these and several other points in the open literature when the EU risk assessment for zinc has been completed and all parties to it are free to publish.

I also question the author's claim that the paper should be considered state-of-the-art in (zinc) risk assessment. In particular, the paper presents a traditional deterministic risk assessment, whilst the data-rich nature of the zinc case allows for a more sophisticated probabilistic approach, as outlined by Van Sprang et al. (2004) with the use basically of the same data. The paper further suggests that the PNECs cited are useful for setting water quality standards and sanitation levels. I challenge this latter conclusion in light of the above and urge readers to exercise caution in interpreting the publication of a risk assessment that is not yet fully finalized.