**10. Outlook**

The poor biodegradability of PBDEs means that both the accumulation of PBDEs in the food chain and inhalation exposure will continue to be highly relevant issues in the next few decades. Problems comparable to those described for PBDEs are also expected for alternative brominated flame retardants such as hexabromobenzene, pentabromotoluene, 1,2-bis-(2,4,6-tribromophenoxy)ethane, or decabromodiphenylethane due to the likewise high degree of bromination, high persistence and thus a high bioaccumulation potential [20, 84]. A ubiquitous presence of these compounds was already proven [19].

Especially remarkable is the partial lack of metadata in existing publications, which makes an comprehensive evaluation, as it was tried in this publication, difficult. This concerns, for example, more detailed information about the soil composition, the content of organic carbon, lipid, and water of roots and shoots. Thinning of data, such as the aggregation of single congener data to sums (e.g. ∑PBDE) without further information about the composition makes a valuable data set useless.
