Ecotoxicology seminar from Toxicology 12. 10. 2021 M. Chalupová Ecotoxicology Ecotoxicology • basis for determining the effects of contaminants on ecosystem is at organism level • at organism level, response can be: – acute toxicity causing mortality – chronically accumulating damage ultimately causing death – sublethal impairment of various aspects of physiology and morphology – sublethal behavioral effects – measurable biochemical changes Toxicology vs. Ecotoxicology • Absorption • Distribution • Metabolisation • Elimination • Release into the environment • Fate and disposition • Metabolism • No counterpart Toxicology vs. Ecotoxicology • host defence mechanisms • individual susceptibility • single effects • cumulative exposure • bioaccumulation • bioconcentration (in water) • biomagnification • never single effects • movement between media (water, air…) Risks Embryonic period • peak period of risk is first trimester, first ten weeks, during organogenesis • severe damage is likely to result in spontaneous abortion Fetal development • some late developing organs • neurological development and behaviour • cancer risk Risks After birth • lactation and exposure through breast milk • environmental exposure Toddlers and young children • accidental exposures • inquisitive behaviour • compulsive ingestion • higher minute ventilation • more active, behaviourally and metabolically • growing • incomplete defenses and physiological barriers Assessment of Structural Changes Changes in species / population structure • appearance/disappearance of an indicator species • number of individuals of a species • biomass of a species • presence or absence of a species Changes in community/ecosystem structure • biomass • abundance • biotic indices (e.g. trophic types) • species richness / diversity • dominance • food chain length/complexity Chemicals of Interest • DDT (DDE), aldrin, hexachlorobenzene, PCBs, dioxines • remain in the environment for a long time, very stable • resist chemical and biological degradation • it leads to their persistence and ubiquitous nature in the environment • almost all chemicals of ecotoxicological interest are bioavailable and in most cases undergo bioaccumulation and biomagnification (food chain) Chemical Behaviour BIOAVAILABILITY • fraction of a chemical in the available form to organisms e.g. fish: food, absorption from water BIOCONCENTRATION • chemical concentration in an organism exceeds the concentration in the surrounding media (water) as a result of exposure through the respiratory surfaces (gills/dermal surfaces) - not food! • referring to uptake and accumulation of a substance from water alone Chemical Behaviour BIOACCUMULATION • accumulation of chemicals in the tissue of organisms through any route, including respiration, ingestion, or direct contact with contaminated water, sediment, and pore water in the sediment • bioaccumulation factor: c in organism/c in food (or ingested water) BIOMAGNIFICATION • increased concentration of substances (DDT) in the organisms at higher trophic levels or food chains • biomagnification factor: c in predator/ c in prey Biomagnification and Bioaccumulation • environmental persistence • lipophilicity • biotransformation • plankton • small fish • predatory fish • animals and humans Methylmercury Terrestrial Ecosystems CONTAMINATED SOILS • by metals and radioactive isotopes resulting from – industrial, mining or deposition from agricultural practices such as application of metal-containing pesticides or metal-contaminated sewage sludge – wet or dry deposition from smelting activity – lead-containing car exhaust – atmospheric nuclear weapon testing or accidents such as Chernobyl Metals • non-biodegradable • formation and degradation of organometallic compounds like methylmercury (MeHg) • bio-accumulation of cadmium (Cd) is higher than most metals as it is assimilated rapidly and excreted slowly • aluminium (Al) – insoluble at normal to slightly acidic pH but below pH 4.5 solubility increases dramatically and becomes responsible for fish kills in acidified lakes Aquatic Ecosystems • the ultimate “sink” for metals is the ocean but difficult to estimate the effect on living organisms due to the massive dilution • effect of metals on biota is much felt in estuaries especially those receiving water from contaminated sites • in estuaries the flow rate diminishes, suspended sediments settled and dissolved metals precipitated • contaminated water affects organisms Bioindicators • species used to monitor the health of an environment or ecosystem Plant indicators • mosses, lichens, fungi, algae Animal indicators • organisms are monitored for changes (biochemical, physiological, behavioral) that may indicate a problem within the ecosystem – content of certain elements or compounds – their morphological or cellular structure – metabolic-biochemical processes – behaviour – population structure Air Pollution • sulphur (SOX) and nitrogen oxides (NOx) • carbon monoxide (CO) • carbon dioxide (CO2) • fine particles • volatile organic compounds • ground-level ozone (O3) HEALTH RISKS • heart diseases (stroke) • pulmonary diseases (COPD, bronchial asthma, cystic fibrosis) • lung cancer Water Pollution • contamination of groundwater, lakes, rivers, oceans, aquifers Chemicals • detergents • disinfectants • herbicides • insecticides Pathogens • coliform bacteria Common Environmental Toxicants PCBs (polychlorinated biphenyls) • cooling and hydraulic fluids Pesticides • destroying, or repelling any organism which may be considered harmful (fungi, insects, weeds) Phthalates • plastic bottles and wraps Dioxins • result of combustion processes – waste incineration and burning fuels (wood, coal, and oil) Heavy metals (arsenic, mercury, lead, cadmium) • fish Asbestos • insulation of ceilings, heating ducts Ecosystem Relations