Problems faced when evaluating the bioaccumulation potential of substances under REACH

Abstract

The identification and regulation of substances that combine persistence, bioaccumulation potential, and toxicity ("PBT" substances) is one central aspect of the European chemical legislation REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals), because these substances may elicit adverse long-term effects after release to the environment. The determination of a substance that has persistence, bioaccumulation potential, and toxicity is based on a set of distinct cutoff criteria identified in Annex XIII of the REACH regulation. Regarding the bioaccumulation potential, the evaluation is focused on the substance's bioconcentration factor as single decisive criterion. In addition, the REACH guidelines provide a selection of standardized test procedures for measuring bioconcentration factor and guidance in appraising test results. However, alternative test results like bioaccumulation factors and biomagnification as well as additional indications for a bioaccumulation potential such as trophic magnification are only allowed for supporting evidence. The currently used test systems with aquatic exposure have been demonstrated to generate reliable results for the majority of neutral, lipophilic organic substances, which facilitate clear decision-making by means of the crucial bioconcentration factor cutoff criteria of Annex XIII. However, certain substance groups such as highly hydrophobic organic substances and amphiphilic and nonlipophilic compounds are difficult to evaluate with common test strategies due to inappropriate test systems or accumulation mechanisms not based on lipophilicity. Recent scientific progress has already been made to establish alternative test systems and to refine the bioaccumulation assessment by consideration of additive accumulation mechanisms and indications. This article gives an overview on actual shortcomings in the current bioaccumulation assessment under REACH and also provides suggestions for a refinement of evaluation.

Occurrence and seasonal loads of pesticides in surface water and suspended particulate matter from a wetland of worldwide interest—the Ria Formosa Lagoon, Portugal

“…Only the total amounts of nitrogen were above the maximum levels established for superficial waters (1 mg/L; Ministério do Ambiente 1998), being 5-fold higher at S1 (close to city of Faro). The same was verified for the un-ionized ammonia levels (maximum toxic level for fish 0.06 mg/L; Durborow et al 1997). These levels may be related to the regional agriculture (mainly orchards) and/or leisure sports (viz.…”

“…Among the most toxic pesticides are the organochlorine pesticides, recognized to have potential to induce hormonal disruption and cancer (Ehrlich et al 2011;Mearns et al 2012;Vallack et al 1998), mainly due to their extreme persistency, bioaccumulating and/or rippling through the food chain (Chopra et al 2011;Katagi 2010). So, the abusive use of pesticides and inefficient treatment of residues increase their probability of reaching estuarine and marine environments affecting fish nurseries as well as the benthic and pelagic communities (Liu et al 2008;McMillin and Means 1996).…”

Mathematical relationships between metrics of chemical bioaccumulation in fish

“…Chemical uptake is by exposure to chemicals in the water only. In a regulatory context, a BCF of 5000 (i.e., 5% of K OW of 10 5 ) is often used as a screening tool for evidence of high bioconcentration; however, depending on the regulatory program, lower values are also used to categorize bioaccumulation potential [7]. Empirical determinations of BCFs are preferred.…”

“…Determining the approach to steady state is usually not feasible in the field. For regulatory purposes, a BAF exceeding 5000 has often been applied when defining a chemical as bioaccumulative, although other criteria have also been suggested [6,7].…”

“…As part of this initiative, various kinds of bioaccumulation data and metrics are used to determine whether and to what extent chemicals are bioaccumulative. Extensive literature exists on bioaccumulation from scientific and regulatory perspectives, examples being the reviews by Barber [3,4], Mackay and Fraser [5], Arnot and Gobas [6], Ehrlich et al [7], Burkhard et al [8], and Gobas et al [9], the latter summarizing the conclusions of a SETAC-sponsored workshop held in 2008. These and other reviews have pointed out the existence of several metrics of bioaccumulation that differ in definition, in regulatory application, and in adoption by the scientific community.…”