A wide spectrum of chemicals of both anthropogenic and natural
origin is present in the environment. Environmental
compartments contain mixtures of compounds with diverse
physical-chemical properties and potential biological activity.
Some of the compounds can interact with the endocrine system of
wildlife species and humans and cause adverse health effects.
Environmental chemicals can exert endocrine disrupting activity
by multiple mechanisms, e.g. interfere with the production,
release, transport, metabolism, binding, action or elimination
of natural hormones.
This thesis is focused on the assessment of contamination of
different compartments in the environment by compounds with
several important mechanisms of action using in vitro
bioassays. Specifically, it is concerned with the interference
of complex environmental mixtures with the signalling of three
intracellular receptors (estrogen, androgen and aryl
hydrocarbon receptor).
This thesis is divided into three thematic parts covering
assessment of contamination of different types of samples from
rivers by in vitro bioassays, combination of in vitro and in
vivo bioassays for aquatic contamination assessment and
determination of air contamination by compounds with specific
mechanisms of action. Presented results are based on four
published scientific publications and two manuscripts.
First part of the thesis is focused on pollution of aquatic
environment. Several types of samples were collected in rivers
from two model areas in the Czech Republic, tested for specific
effects and chemically analyzed. In Papers I and II, impact of
a city agglomeration and wastewater treatment plant (WWTP) on
contamination of the river ecosystem was studied using
sediments, two types of passive samplers (SPMD for hydrophobic
compounds and POCIS for polar compounds) and composite waste
water samples. The results indicated contribution of the city
agglomeration and the WWTP to the rivers contamination by
different types of compounds. Distribution of specific
activities among sediments, waste waters, SPMD and POCIS was
shown, with cytotoxicity and dioxin-like activity in all types
of samples. Estrogenic and androgenic activities were detected
in WWTP samples, while there were antiestrogenicity and
antiandrogenicity in river samples. The WWTP water samples
collected monthly 
whole year enabled evaluation of seasonality and treatment
efficiency of the WWTP. Seasonal variability was studied using
samples collected during four sampling campaigns. Sediments
showed the most obvious trends and least variability, and
confirmed that they represent suitable media for pollution
assessment since they reflect longer-term situation in the
rivers.   
Regional and seasonal variability of contamination of sediments
from another industrial region was studied and described in
Paper III. The aims of the study were examination of
associations among chemical, abiotic and biological parameters,
quantification of main sources of variability in the
environmental data and their influence on bioindication
potential of the bioassays. The study documented strong
indication potential of specific bioassays for changes in
contamination and also significance of abiotic factors in
accumulation of pollutants.
Second part of the thesis describes use of in vivo assay with
freshwater mud snail Potamopyrgus antipodarum, in vitro
bioassays and chemical analyses for complex assessment of
polluted sediments (Paper IV) and contamination of the river
ecosystem (Paper V). In laboratory study with polluted
sediments and also in the in situ test performed at the same
sampling sites as Papers I and II, fertility of P. antipodarum
was affected and toxic effects were observed.
Third part of the thesis is focused on the assessment of
contamination of particulate and gas phase of air by compounds
with specific effects. Dioxin-like activity and
antiestrogenicity were detected in most samples, antiandrogenic
activity was observed in all gas phase samples and to a lesser
extent in particulate phase of air samples. This study provided
important information about distribution of specific effects
between gas and particulate phase of air samples that are not
studied as often as aquatic environment.
All studies included in this thesis document that in vitro
bioassays represent a suitable technique for the assessment of
environmental contamination by compounds with endocrine
disruptive potency. They enable to determine overall biological
activity of chemicals acting through the same mechanism of
action in complex environmental samples including interactions
within the mixtures.