Chapter 11: Bioaccumulation Flashcards
What is ecotoxicology?
Ecotoxicology is the study of the fate and effects of toxicants in an ecosystem.
What is bioavailability?
Bioavailability is the portion of a toxicant that can potentially be absorbed by an organism.
What are the four different matrices that toxicants can move between?
The four different matrices are atmosphere, lithosphere, hydrosphere, and biosphere.
What are point sources of pollution?
Point sources of pollution are from a discrete source, such as discharge pipes or effluent.
What is the difference between bioaccumulation and bioconcentration?
Bioaccumulation is when concentration in an organism is higher than the concentration in the environment by absorption AND ingestion, while bioconcentration is when concentration in an organism is higher than the concentration in the environment by absorption only.
What is BCF, and what does it tell us about the accumulation of toxicants in organisms?
BCF stands for bioconcentration factor, and it tells us whether a toxicant is actively excluded, exhibits no selectivity, or is accumulated within an organism at a higher quantity than in the environment.
What is the definition of biomagnification?
Biomagnification is the process in which some toxicants become increasingly concentrated at successively higher trophic levels, via predators feeding on prey items.
What is the definition of trophic dilution?
Trophic dilution, also known as biodilution, is the opposite of biomagnification. It occurs when concentrations of toxicants decrease with increasing trophic level.
What are the four ways that toxicants can break down in the environment?
The four ways that toxicants can break down in the environment are photolysis, oxidation, hydrolysis, and microbial metabolism.
What is the chemical structure of persistent organic pollutants (POPs)?
Persistent organic pollutants (POPs) have a chemical structure that makes them resistant to breakdown by photolysis, oxidation, and hydrolysis.
What are some characteristics of PHAHs?
Some characteristics of PHAHs (polychlorinated and polybrominated aromatic hydrocarbons) include high lipophilicity, slow breakdown in the environment, potential for biomagnification, and potential interactions with other toxicants.
What are PHAHs and how are they formed?
PHAHs (Polyhalogenated Aromatic Hydrocarbons) are important toxicants that have bicyclic aromatic rings. They are generally formed as products of a reaction between organics and chlorine or other halogens (Br, Fl).
What makes molecules containing halogens difficult to metabolize?
Halogens bonded covalently to carbon are relatively rare in nature, which makes molecules containing them more difficult to metabolize.
How many kinds of Polychlorinated Biphenyls (PCBs) are there and what are they called?
There are 209 different kinds of PCBs, and they are called different “isomers” and “congeners”.
What is the most toxic form of PCBs?
The most toxic forms of PCBs are highly effective at binding at cellular target sites and are resistant to detoxification mechanisms.
What led to the wide use of PCBs in the past?
High thermal stability led to the wide use of PCBs in transformers and capacitors, as heat transfer fluids, plasticizers, adhesives, lubricants, flame retardants, and extenders or diluents of other agents.
What are some ways that environmental contamination by PCBs can occur?
Environmental contamination by PCBs can result from open burning and incomplete combustion of PCB-containing solid waste, vaporization from open system applications, accidental spills or leakages from closed system applications, and disposal of waste into sewage systems.
What is the estimated amount of PCBs in the environment, and where are they distributed?
There is an estimate of about 400,000 tons of PCBs in the environment, with 60% in the hydrosphere, 39% in the terrestrial system, and 1% in the atmosphere.
What is chloracne, and what causes it?
Chloracne is an acne-like skin condition caused by certain toxic chemicals including PCBs and PCDDs. It develops a few months after swallowing, inhaling, or touching the responsible agent.
What are some symptoms of exposure to PCBs?
Symptoms of exposure to PCBs can include nausea, vomiting, fatigue, vitamin A depletion, liver damage, hormonal changes (thyroidal effects), and lung and liver carcinogenicity.
What is endocrine signaling?
Endocrine signaling is when a hormone is made in one area of the body, is released into the blood stream, and the signal is received by another cell in the body.
What hormones are released by the thyroid gland?
The thyroid gland releases thyroid hormones [thyroxine (T4) and triiodothyronine (T3)].
What is the function of T3 and T4 hormones?
T3 and T4 hormones signal to other cells to increase metabolism among other things. T3 is the more potent hormone.
What is the role of thyroid hormones in neurological development?
Thyroid hormones are involved in neurological development in utero and during early childhood.
