Environmental toxicology Flashcards
(40 cards)
What is the difference between natural toxins and toxins of anthropogenic origin?
Natural toxins are from within the environment, while anthropogenic toxins are introduced into the environment by human activities.
Natural toxins include substances like endotoxins, while anthropogenic toxins include pesticides and industrial chemicals.
What are exogenous toxins?
Toxins introduced into the environment, such as organochlorine pesticides, heavy metals, and PCBs.
Exogenous toxins contrast with endogenous toxins, which are naturally occurring within organisms.
List examples of natural toxins that are more potent than man-made toxins.
- Tetrodotoxin
- Botulinum toxins
- Aflatoxins
- Saxitoxin
- Venoms
These toxins can have severe effects on living organisms.
Define xenobiotic.
A substance that is foreign to a live organism, such as atrazine, a chlorinated herbicide.
Xenobiotics can include both natural and synthetic substances.
What is the role of experimental toxicology?
To assess the toxicology of substances in controlled settings, which may differ from in vivo situations in the field.
This highlights the challenge of translating lab results to real-world scenarios.
What are the different categories of toxins based on their origin?
- Endogenous toxins (endotoxins)
- Exogenous toxins (exotoxins)
- Elemental toxins
- Gaseous toxins
- Plant secondary metabolites
- Mycotoxins
- Bacterial toxins
- Animal toxins
Each category has distinct sources and effects.
What are the main types of pesticides?
- Insecticides
- Fungicides
- Herbicides
- Rodenticides
- Acaricides
- Bactericides
- Molluscicides
These are used to control unwanted organisms in agriculture and other settings.
What is the significance of the n-octanol-water partition coefficient (LogP)?
It indicates a substance’s potential to bio-accumulate; higher values suggest greater bio-accumulation potential.
LogP also influences the molecule’s behavior in the environment.
What are the main compartments of an ecosystem?
- Atmosphere
- Geosphere (terrestrial environment)
- Hydrosphere (aquatic environment)
- Biosphere (living organisms)
These compartments interact with each other and are essential for life.
Fill in the blank: A _______ is any chemical or biological substance used to kill or disrupt undesired organisms.
[pesticide]
True or False: Natural organic pesticides originate from living organisms.
True
Examples include pyrethrins and azadirachtin.
What factors influence the mobility of pesticides between different environmental spheres?
- Water solubility
- Vapour pressure
- Stability at various pH levels
- Half-life (DT50)
- Susceptibility to photolysis
- Polarity of the molecule
- Adsorption to soil particles
These factors determine how pesticides behave and move in the environment.
What is medical (clinical) toxicology?
The study of the fate of toxic substances and their effects on people.
This includes natural toxins, venoms, pharmaceuticals, and industrial chemicals.
What is environmental (eco) toxicology?
The study of the fate of toxic substances and their effects on ecosystems, including all living taxa.
Environmental toxicology encompasses a wide range of substances and their interactions within ecosystems.
What are the critical substances for life on Earth?
- H2O (water)
- O2 (oxygen)
These substances are essential for the survival of living organisms.
True or False: Soil rich in clay minerals has a high affinity for polar substances.
True
Clay minerals can strongly adsorb polar substances due to their structure.
What are the effects of human activity on the release of endotoxins?
Human activity can unleash endotoxins from ore bodies into the lithosphere and hydrosphere as anthropogenic or exogenous toxins.
Mining and exploration are significant contributors to this process.
What is the impact of pesticides on the environment during their lifecycle?
Pesticides can enter the environment during manufacturing, storage, application, and can contaminate multiple spheres including lithosphere, hydrosphere, and atmosphere.
Their movement and degradation are influenced by various environmental factors.
What is the relationship between active surface area of soil and particle surface areas?
The active surface area of a mass unit of soil is directly correlated with the sum of the surface areas of all the particles in that quantity.
How do finer particles affect the quantity of adsorbed polar substances?
Finer particles increase the quantity of adsorbed polar substances.
What role does compost and beneficial microbes play in soil?
Soil rich in compost, beneficial nematodes, and beneficial microbes degrade pollutants such as pesticides due to the abundance of enzymes produced by the living soil biota.
Which type of molecules can microbes decompose rapidly?
Microbes can decompose molecules with low Kow (LogP) values rapidly.
What is the natural pH range of water due to dissolved carbon dioxide?
Natural water pH is typically between 5.5 to 6.5.
How does pH affect pesticide stability?
Most pesticides are stable at pH levels of 5.5 to 7; stability decreases with a decrease in pH and most pesticides are unstable in alkaline water with pH > 8.
