Lecture #3 Flashcards
October 8, 2020
toxin
a naturally produced toxic chemical
toxicant
a manmade toxic chemical
Chemicals by Function: Flame Retardants
- PBDE (polybrominated diphenylethers)
- HBCDD (hexabromocyclododecane)
- TBBPA (tetrabromobisphenol-A)
Chemicals by Function: Pesticides
- OCPS (organochlorine pesticides like DDT)
- OPs (organophosphates)
- neonicotinoids
Chemicals by Function: Pharmaceuticals/ Personal Care
- nitromusks (fragrances)
- antibiotics
- drugs and hormones (EX: birth control pills)
Chemicals by Function: Misc. Industrial Chemicals
- CFC (chlorfluorocarbon)
- PFC (perfluorocarbon)
- PCBs (polychlorinated biphenyls)
Chemicals by Function: Plastics/Plasticizers
- plastic constituents (like BPA)
- plastic plasticizers (like pthalates)
Chemicals by Function: Hydrocarbons
- polyaromatic hydrocarbons
- alcohols, phenols
- alkanes and alkenes
endocrine disrupting chemicals
any chemical that interferes/interacts with the hormone systems (usually sex hormones)
teratogens
chemicals that affect embryo development
carcinogens
chemicals that promote cancer
neurotoxins
chemicals that poison the nervous system
USEPA Toxic Release Inventory
keeps track of all toxic releases
environmental chemodynamics
- the study of the path of chemicals in the environment, how they move and where they end up based on physical properties
- chemicals are trying to reach equilibrium
fugacity
- the escape potential of a compound
- has units of pressure
- way to predict the sizes of the arrows between compartments
- some chemicals, like DDT, are happier in fish than in water
- more accurate than concentration for predicting the movement of chemicals
4 behaviors of chemicals that govern their partitioning
- adsorption
- dissolution
- volatility
- photostability
adsorption
- tendency to bind or stick to sediments and other substrates
- most inorganic mercury in the ocean is bound to sediments
- the binding constant (Ks = conc. in sand/conc. in water) is only true AT EQUILIBRIUM
volatilization
- every substance has a vapor pressure dependent on temperature
- moving into atmosphere
- Henry’s constant (conc. air/conc. water) describes the volatilization of organic molecules from water
- ~Hc > 10^-5 is volatilizing
dissolution
- solubility
- water is a nearly universal solvent but it prefers polar compounds
- pH and salinity affect solubility
photostability
- many compounds absorb energy from sunlight, mostly from UV, which will change their properties
- can make more or less potent
4 properties of the environment that govern partitioning
- dispersion
- advection
- atmospheric/oceanic transport
- biotransport
bioconcentration
- passive movement of chemical into organism
- akin to solvent switching
biomagnification
- increase in concentration as you go up the food chain
- akin to solvent depletion
bioaccumulation
sum of bioconcentration and biomagnification
How to measure pollutant levels directly
extract the lipid soluble component from fish slurry and run it through a mass spectrometer
bioconcentration factor (BCF or BAF)
conc. in animal/conc. in environment
expressed on a log scale
log BCF = 6 means there’s 1 million times as much chemical in the organism as in the environment
solubility of organic compounds
- very nonpolar
- usually much more soluble in lipids than in water
- octanol used to estimate solubility in fats
UV light reacting with CFCs
- chlorofluorocarbons
- the radiation strips off a chlorine, which then reacts with ozone to make ClO and O2
- degrades ozone layer
