Comparison of solid-phase and eluate assays to gauge the
ecotoxicological risk of organic wastes on soil organisms
, Josep M. Alca
niz, Pilar Andre
Center for Ecological Research and Forestry Applications (CREAF) and Unit of Ecology, Department of Animal and Plant Biology and Ecology,
Autonomous University of Barcelona, Ediﬁci de Ciencies, E-08193 Bellaterra, Barcelona, Spain
Received 8 January 2007; received in revised form 26 March 2007; accepted 8 April 2007
Comparison of solid-phase and eluate bioassays for organic waste testing.
Development of methodologies to assess the safety of reusing polluted organic wastes in soil is a priority in Europe. In this study, and coupled
with chemical analysis, seven organic wastes were subjected to different aquatic and soil bioassays. Tests were carried out with solid-phase waste
and three different waste eluates (water, methanol, and dichloromethane).
Solid-phase assays were indicated as the most suitable for waste testing not only in terms of relevance for real situations, but also because
toxicity in eluates was generally not representative of the chronic effects in solid-phase.
No general correlations were found between toxicity and waste pollutant burden, neither in solid-phase nor in eluate assays, showing the
inability of chemical methods to predict the ecotoxicological risks of wastes. On the contrary, several physicochemical parameters reﬂecting
the degree of low organic matter stability in wastes were the main contributors to the acute toxicity seen in collembolans and daphnids.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Organic wastes ecotoxicity; Solid-phase tests; Eluate tests
There is increasing interest in the development of bioassays
to evaluate the suitability of polluted organic wastes for safe
application to soils excluding any ecotoxicological risk. The
complex nature of such wastes, especially in the case of sew-
age sludge, containing a huge number of potentially noxious
chemicals (Thornton et al., 2001), and the limitations of chem-
ical methods to assess their risk to soils (Crouau et al., 2002)
favours using a bioassay approach.
A wide variety of literature dealing with potential effects on
crops of polluted organic wastes is available, mainly centered
on sewage sludge, while less is known about effects on soil
fauna, a key group in soil agroecosystems (Giller et al.,
1997; Neher, 1999). No harmful effects on soil fauna have
been found in ﬁeld studies using agronomic dosages (Cole
et al., 2001; Kielhorn et al., 1999; Krogh et al., 1997; Petersen
et al., 2003), although some laboratory studies have indicated
risk for soil fauna if such wastes are applied to soils (Andre
and Domene, 2005; Krogh et al., 1997; Krogh and Pedersen,
1997). This scarcity of studies shows how incomplete the
knowledge on this subject is and is a sign of the current need
for the selection of bioassays to assess the ecotoxicological
risk of wastes to soils.
Among the laboratory studies centered on organic waste
ecotoxicity, most have been carried out using waste eluates
or leachates and aquatic ecotoxicity tests. However, others
have focused on the suitability of solid-phase bioassays for or-
ganic wastes using terrestrial organisms. The latter approach is
the most relevant as it provides results closer to those expected
in ﬁeld conditions. However, solid-phase assays have several
drawbacks associated to the organic matter matrix. Organic
* Corresponding author. Tel.: þ34 935 811 312; fax: þ34 935 814 151.
E-mail address: firstname.lastname@example.org (X. Domene).
0269-7491/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
Available online at www.sciencedirect.com
Environmental Pollution 151 (2008) 549e558