Q 1: chapter 2 Flashcards
when was there an enormous increase in the use of chemicals in agriculture, industrial manufacturing, and around the home
during the 1950s and 1960
example: We powdered our bodies with DDT to remove lice and spread DDT far and wide to control mosquitoes. We used other pesticides to kill insects and control weeds in an effort to improve crop yields. Lead was added to gasoline to make cars run better and added to house paint to make it last longer. At the same time we took advantage of the more sinister qualities of lead when we combined it with arsenic to spray on fruit trees to control pests. Pulp and paper mills used mercury to control fungi and molds to ensure that our paper remained white. Seeds were coated with mercury to stop soil fungi. Thermometers, thermostats, and switches brought mercury into everyone’s home and school
how does mercury and lead affect humans
developmental effects, harming the developing nervous system for a lifetime
how do chemicals contribute to their toxicity to humans and other species
1: they are persistent- dont breakdown in the environment or very slow so the amount is continuously rising
2: pesticides didnt only kill their intended target
3: bioaccumulate or concentrate in species as they move up the food chain- lead accumulates in bone and methylmercury in muscle
4: because of their persistence in the environment and accumulation in various species, the persistent toxicants spread around the world, even to places that never used them
what was done to address the public and environmental health concerns caused by these and other compound
government agencies have initiated various programs and regulations to control or restrict the use of the offending substances. Laws were passed to ensure more rigorous testing of compounds before widespread use, although this was not entirely effectiv
what is the tsca, when was it passed
US Toxic Substances Control Act, 1976 but has been largely ineffective for chemical management.
what is the FQPA and when was it passed
US Food Quality Protection Act (FQPA) of 1996. it was more effective in implementing pesticide testing requirements. Researchers worked to develop new pesticides and other agents that were more specific in their toxicity and much less persistent. The use of many of the persistent chemical pesticides was restricted or even banned in some places. Individual countries are responsible for regulations, so there are some countries that still use pesticides that are banned elsewhere
what is the UNEP
was more effective in implementing pesticide testing requirements. Researchers worked to develop new pesticides and other agents that were more specific in their toxicity and much less persistent. The use of many of the persistent chemical pesticides was restricted or even banned in some places. Individual countries are responsible for regulations, so there are some countries that still use pesticides that are banned elsewhere
what are PBT
Persistent Bioaccumulative and Toxic
what does exposure depend on
s location, diet, housing, occupation, and socioeconomic issues
what is IPM
. Integrated Pest Management (IPM, see definition below) is an approach to pest control that can significantly reduce pesticide use while still providing adequate or even improved results. IPM programs are used in agriculture, landscaping, and indoor pest control. Typically, IPM programs maximize prevention of pest problems through nonchemical methods, and chemicals, when used, are selected for minimum risk to nontarget species.
What is the Lindane Dump Site?
Used as a pesticide for many years this persistant agent is still used today in the elimination of fleas and nats. Industrial dumpsites such as the one in Allegheny County, Pennsylvania contain an estimated 400 tons of lindane waste and other waste dumped over a 50-year period on 30 acres of land. The runoff from this site as well as others have the potential to contaminate drinking water with lindane. Lindane is regularly detected in surface water in the United States (see US Geological Survey monitoring studies).
dioxin
Extremely Toxic – dose makes the poison (DMTP)
Extremely Expensive to clean up
Extremely Low Concentrations - DMTP
are dioxins persistant
yes they will stay for decades- MAN MADE
what is dioxins LD-50
0.001
where are dioxins found in our food
dairy, meat,fish, fatty foods
what does PCDD
POLYCHLORINATEd-p-dioxins
what does PCDFs
polychlorinated dibenzoFURAN
In what family does dioxins and furan belong to
halogenated aromatic compounds
how many isomers do dioxins have
75
how many isomers do furans have
135
how many chlorines do dioxins and furans have
1-8
which has a single oxygen bridge- dioxins or furans
furans
which is the most toxic of the dioxins
TCDD-2,3,7,8-tetrachlorodibenzo-p-dioxin
how do you mesure a PCDD/Fs potency
it is additive
how are dioxins mesured
parts per trillion- aka picogram (pg)/g
when did we find about dioxins
1970Saw effects but didn’t know the cause
Could not even measure until the late 1970’s
Accurate techniques for low ppt analysis not available until the late 1980s
what is the difference btw urban and rural air in terms of dioxins
1-50pg/m3 vs.
where are dioxins most common
in sediment- acts like fat
Symptoms of dioxins found in what animals?
Trout and Great lake fish eating birds.
Viktor Yushchenko
Very likely poisoned by TCDD: Blood levels were 50,000 times higher then normal population.`
Toxic responces to dioxin?
Wasting syndrome: weight loss not related to food consumption
Skin: acneform eruptions (chloracne), edema, hyperkeratosis
Hyperplasia of extrahepatic bile duct, gall bladder & urinary tract
Lymphoid involution; thymic/spleenic atrophy
- immunesuppression
Liver damage: necrosis, tumors
Porphyria: disordered porphyrin metabolism (skin blistering/fragility)
Endocrine and reproductive dysfunction
Teratogenesis (deformities and birth defects)
Carcinogenesis: e.g., hepatocarcinoma
Highly species dependent – similar species can be 1,000s of times more or less sensitive
Sources of PCDD /f’s
Unwanted by-products of chemical processes (any combustion process with chlorine present)
Industrial sources associated with the production of chlorinated phenols (e.g., pentachlorophenol), phenoxy herbicides (e.g., 2,4-D, 2,4,5-T)
Pulp and paper industry, metallurgical processes, chlor-alkali process
Municipal, hospital and industrial waste incinerators - fly ash, Sewage sludge, automobile exhaust (largest source ? ?)
Times Beach Missouri
Town completely evacuated because of dioxin contamination.
Due to a dust problem in the 1970s 23 miles (37km) of dirt roads in the ‘city’ of Times Beach, Russell Bliss was contracted to oil roads.
From 1972 to 1976, Bliss sprayed waste oil on the roads for 6c /gal.
Bliss contracted with a company called IPC to dispose of toxic waste. IPC was paid $3,000/ load to remove toxic waste fromNortheastern Pharmaceutical and Chemical Company(NEPACCO)
IPC in turn paid Bliss $125 to ‘eliminate’ the waste. NEPACCO producedhexachlorophene from 2,4,5-TCP, inVerona, MO
Bliss claimed he was unaware that the waste contained dioxin, having even sprayed it around his own home
Times Beach (population 2,800) covered 8 square miles on the floodplain of the Meramec River in St. Louis County, Missouri
In Nov-Dec 1982, EPA sampled the roads in Times Beach. Soon afterward, the Meramec River flooded the City.
EPA rushed the analyses and found dioxin
2,4,5-T
If it isn’t created responsibly it can turn into dioxins. Responsible for Times Beach
In Vietnam how much of the TCDD reached the ground and what happened to the amount that didnt?
less then 5% reached the ground and the other 95% landed in the canopy’s which allowed the light to degrade it(half life 6 hours)
What degrades TCDD?
UV light.
Tolerability level for us Canadians?
In Canada the “tolerable” level (meaning no serious health effects are expected) is 70 pg/kg body weight/month. This is about 2.3 pg/kg body weight/day
“Studies done between 1998 and 1999 in two Canadian cities showed that the average dietary intake of dioxins, was 0.62 pg/kg body weight/day. This is well within the level considered tolerable by Joint Expert Committee on Food Additives”
See “It’s Your Health” from Health Canada – posted on BlackBoard
