Evaluating chemical exposure and effect models for aquatic species with a focus on crude oil ...

224 Pages·2016·26.24 MB·English

Evaluating chemical exposure and
effect models for aquatic species
with a focus on crude oil constituents
Lisette de Hoop
De Hoop, L., 2016. Evaluating chemical exposure and effect models for aquatic species
with a focus on crude oil constituents. PhD thesis, Radboud University Nijmegen, The
Netherlands.
Cover & layout: Roel van den Heuvel
Printed by: Ipskamp Drukkers, Nijmegen
© 2016 Lisette de Hoop, all rights reserved.
ISBN 978-90-9029883-2
Evaluating chemical exposure and
effect models for aquatic species
with a focus on crude oil constituents
Proefschrift
ter verkrijging van de graad van doctor
aan de Radboud Universiteit Nijmegen
op gezag van de rector magnificus,
volgens besluit van het college van decanen
in het openbaar te verdedigen op
vrijdag 2 september 2016
om 16.30 uur precies
door
Lisette de Hoop
geboren op 22 augustus 1988
te Vlissingen
Promotoren
Prof. dr. ir. A.J. Hendriks
Prof. dr. M.A.J. Huijbregts
Copromotoren
Dr. A.M. Schipper
Dr. F. de Laender (Université de Namur, België)
Manuscriptcommissie
Prof. dr. A.M. Breure (voorzitter)
Prof. dr. A.P. van Wezel (Universiteit Utrecht)
Dr. R.S.E.W. Leuven
Paranimfen
Stephanie van Dalen
Thomas van Goethem
CONTENTS
Chapter 1 General introduction 7
Chapter 2 Modelling bioaccumulation of oil constituents in aquatic species 17
Chapter 3 Time-varying effects of aromatic oil constituents on the survival of 35
aquatic species: deviations between model estimates and observations
Chapter 4 Crude oil affecting the biomass of the marine copepod Calanus 55
finmarchicus: comparing a simple and complex population model
Chapter 5 Modelling toxic stress by atrazine in a marine consumer-resource system 77
Chapter 6 Sensitivity of polar and temperate marine organisms to oil components 97
Chapter 7 Synthesis 109
Appendices
A. Appendix to chapter 2 123
B. Appendix to chapter 3 131
C. Appendix to chapter 4 147
D. Appendix to chapter 5 155
E. Appendix to chapter 6 165
Literature cited 177
Summary 203
Samenvatting 209
Acknowledgements - Dankwoord 215
About the author 221

Chapter 1
General introduction
Chapter 1
1.1 Ecological risk assessment
1.1.1 General concept
Ecological risk assessment (ERA) aims at predicting the probability of occurrence
and the magnitude of adverse effects of chemicals on plants, animals, and
ecosystems. Two main factors determine whether a chemical is a potential risk,
namely its concentration in the environment and the sensitivity of the organisms
exposed, i.e. the chemical dose or concentration that induces an adverse effect,
such as lethality (Figure 1.1). The chemical concentration in an environmental
compartment, such as water, soil or air, is measured or modelled in the exposure
assessment. In the effect assessment, the toxicity of a chemical is determined
by establishing concentration-effect relationships. These relationships can be
used to derive an environmental concentration at which no effect or a generally
acceptable effect occurs, for instance the concentration affecting no more than
5% of the species in an ecosystem. In standard ERA the risk of a chemical is
typically characterized by dividing the environmental exposure concentration
by the no effect or acceptable effect concentration. If the ratio exceeds a value
of 1, the chemical may pose an unacceptable risk to the species or ecosystem of
concern.
Chemical in
environment
Exposure
Effect assessment
assessment
Risk
characterization

Figure 1.1 The standard risk characterization process for chemical substances (modified after Van Leeuwen
and Hermens [1]).
Ecological risks can also be based on internal effect thresholds and body burdens
in biota instead of external exposure and effect concentrations of chemicals [2-
4]. One advantage of the so-called tissue residue approach (TRA) is that the
bioavailability and toxicokinetics (i.e. rates of uptake and elimination) of a
chemical are considered. Because internal thresholds are relatively independent
of the variability in toxicokinetics, differences in species characteristics are
less important in the TRA than in the external concentration approach [4, 5].
Furthermore, internal concentrations integrate exposure over time and space
providing a more stable exposure assessment [4]. Yet, limitations to using the
8
General introduction
TRA include for instance the assessment of highly biotransformable chemicals,
reactive chemicals (e.g. phototoxic chemicals) and inorganics, such as metals [4].
1
1.1.2 Bioaccumulation
A chemical substance can be taken up by an organism via contact with
environmental compartments and via its food. Bioaccumulation occurs when an
organism is unable to eliminate all of the absorbed chemical substances. The
elimination can include different routes, such as via water, faeces, dilution with
biomass and biotransformation of parent compounds into metabolites (Figure
1.2) [6]. Accumulation of a persistent chemical occurs in the fat fraction of the
organism if the chemical has a higher affinity to fat compared to water. The
potential of organic chemicals to bioaccumulate is therefore often assessed as
the octanol-water partition coefficient K , which represents the lipophilicity of
ow
a chemical and how it thermodynamically partitions between aqueous and lipid
phases [7].
The accumulation of a chemical from the water phase can be expressed as a
bioconcentration factor (BCF), which is the ratio of the chemical concentration
in the organism to the chemical concentration in the water [7]. Body burdens
may increase from prey to predator due to dietary absorption, which can
be quantified with the biomagnification factor (BMF), that is the ratio of the
chemical concentration in an organism to that in the organism’s diet [8].

Figure 1.2 Schematic representation of different mechanisms that can carry chemicals into or remove
chemicals from aquatic organisms: assimilation from food, absorption from water, transformation in the
organism, dilution with biomass, egestion with food, and excretion with water.
9
Chapter 1
Models can be used to estimate the bioaccumulation for organic chemicals and
species that have remained untested, in order to limit animal tests and inform
regulatory decision making. Relationships between bioconcentration parameters
(absorption and elimination rate constants) and the lipophilicity of a chemical
substance provide a means for estimating its bioconcentration behaviour [9].
There are different mass-balance models which quantify the bioaccumulation
of chemicals in organisms based on the environmental concentration and first-
order uptake and elimination rate constants:
1. One-compartment models, in which the body is treated as one unit, since
an immediate distribution and equilibrium of the chemical is assumed
throughout the organism’s body [6, 9]. An example is the bioaccumulation
model OMEGA (Optimal Modelling for EcotoxicoloGical Applications),
which has been used for a variety of aquatic and terrestrial vertebrates and
invertebrates exposed to metals and organic chemicals [10, 11].
2. Multi-compartment models, in which extra compartments are added into
which the chemical may distribute. Some models divide the organism into
a number of compartments (water compartment, target compartment, and
others) with a permanent chemical equilibrium among them [12, 13].
1.1.3 Single-species effects
Accumulation of a chemical can result in an adverse effect on the organism if
its body burden exceeds a critical internal threshold level. Concentration-effect
relationships can be used to determine a threshold value, such as the critical
body burden (CBB), e.g. the internal concentration of a chemical at which 50%
of the individuals are negatively affected regarding for instance their growth or
survival. Additionally the concentration-effect curves represent the variation in
sensitivity between individuals, i.e. the intraspecies variation.
The CBB concept is often used for assessing the potential toxicity of chemicals
with a narcotic toxic mode of action (TMoA), i.e. a baseline toxicity [2]. Many
organic compounds, like aromatic hydrocarbons, are expected to exhibit a non-
polar narcotic TMoA, which is believed to be the result of nonspecific disturbance
of membrane integrity and functioning due to partitioning of toxicants into
biological membranes [14]. It is assumed that chemicals with the same TMoA
exhibit a similar CBB, for example 0.1 (0.04-0.16) mol/kg lipid for narcotic
chemicals [5].
1.1.4 Multi-species effects
Multi-species population models are important for ecological risk assessment
as effect estimates on a population level usually lie closer to the interest of risk
assessors than individual-level effect estimates. The abundance of organisms
changes when the demographic vital rates that drive population dynamics,
10