Environment and health
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what is radiation?
the emission of energy as electromagnetic waves or as moving particles.
what are the different types of non-ionizing radiation?
radio frequency (RF), microwave (MW) and Extremely low frequencies (ELF), electromagnetic field (EMF)
two examples of RF and MF
radio and cell phones
example of ELF:
alternative current (AC), power lines, electrical wiring and electrical equipment
what is the cutoff point of ELF by most gvmts?
who are the most exposed to EMF?
welders and electricians
what is ionization?
to carry enough energy to knock out electrons from atoms and molecules.
what amount of radiation is ionizing radiation?
everything produces radiation: T or F
what are the different terms when measuring radiation?
- emitted radiation: amount of radioactive material released in the environment
- radiation dose:amount of energy deposited on human tissue
- biological risk:the risk that a person will suffer health effects from an exposure to radiation.
What are the main routes to exposure to radiation?
- inhalation: alpha and beta particles
- ingestion: alpha and beta
- external exposure: limited for alpha, greater concern for beta, greatest for gamma.
what is a health effect of ionizing radiation?
Acute Radiation Syndrome (ARS)
what is Acute Radiation Syndrome (ARS)?
An acute illness caused by irradiation of the entire (or most of) body by a high dose of penetrating radiation in a short period of time(minutes).
what are the 3 classic ARS
- bone marrow syndrome (hematopoietic syndrome)
- gastrointestinal syndrome
- cardiovascular / central nervous system syndrome
what is the health effect of long term, low level (chronic) radiation exposure?
it involves DNA damage. it is a mutagen, carcinogen and a teratogen.
what are the 4 ways in which people are protected from identified radiation sources?
Limiting exposure time, increasing distance from source, shielding and containment.
name the 4 regulatory bodies of radiation
- Canadian Nuclear Safety Commission
- Health Canada Radiation Protection Branch
- Health Canada National Dosimetry Service
- International Atomic Energy Agency
Why are metals unique as toxicants?
they are neither created not destroyed
in what forms may metals be?
elemental, inorganic salts or organic metal compounds
how do non-essential metal often exert their toxic effects?
by substituting for essential metals that share similar chemistry
what effect can toxic metals have on essential metals?
toxic metals may influence the role of essential metals in cellular processes.
what are the different uses of arsenic?
poison, industrial, agricultural and therapeutic agent
what are the different routes of exposure to arsenic?
dermal, ingestion and inhalation.
what are the different forms arsenic can be present in the body?
As+5, As+3, monomenthyl arsenic (MMA), dimethyl arsenic (DMA) or trimethyl arsenic (TMA)
how is arsenic eliminated and what is its half life?
- kidney. the primary urinary excretion products are MMA and DMA forms.
- t1/2 ~ 10 hrs.
what are the major health effects of arsenic?
liver damage, cardiovascular disease, kidney damage, encephalopathy.
what types of cancer does arsenic cause?
liver, skin and lungs
give an example of cadmium occupational exposure
smelters - Cd is a byproduct of Pb, Zn or Cu smelting.
what are the major health effects of cadmium?
- Liver and extreme kidney damage.
- elimination is very poor
- it disrupt the normal function of Zn
- Chronic pulmonary toxicity
- Acute oral toxicity (rare)
- acute inhalation toxicity (frequent)
what is the half life of cadmium?
t1/2 > 10 yrs
where does lead accumulate the most in the body
what is the half life of lead?
t1/2 > 20 yrs
what are the major health effect of lead?
encephalopathy, anemia, neuropathy, nephropathy.
what are the health effects of mercury?
lungs, CNS, kidney, reproductive/developmental, immune sys.
what are solvents?
Liquid organic chemicals that are used to dissolve, dilute or disperse other chemicals that are insoluble in water. small molecular size and no charge.
how do most solvents enter the environment?
what is also a concern with solvent contamination?
contamination of drinking water supplies
solvent potential for contamination depends on what?
- vapor pressure, density
- specific gravity.
occupational and pediatric poisoning (accidental ingestion)
what does solvent toxicokinetics involve?
absorption, distribution, metabolism
what are the major health effects of solvents?
CNS, tissue irritation, nephrotoxins, hepatotoxins, cardiotoxins,
what are the different regulation of solvent exposure?
- TLV-TWA Threshold Limit Value - Time Weighted Average
- PEL - Permissible Exposure Limit
- STEL - Short Term Exposure Limit
- TLV-C Threshold Limit Value - Ceiling Value
Give example of solvents
- Halogenated hydrocarbon - CNS. heart liver, kidney
- Aromatic hydrocarbon (benzene) - CNS, Bone marrow, leukemia
- Alipathic alcohols (Methanol) - CNS, acidosid, blindness
- Glycols (Ethylene glycol) - kidney, neurotoxicity, met. acidosis.
WHO estimation of pesticides
- 3 million cases
- 220,000 deaths annually
what are the different types of insecticides?
Organochlorines, organophosphates and carbamates, pyrethroids.
how do insecticides work?
poison the CNS
how do organochlorines and pyrethroid act?
by altering the movement of ions across the nerve cell membranes and changing the ability of the neuron to fire.
how do organophosphates and carbamates act?
at the synapse, altering the transmission of the signal from one cell to the next.
organophosphates and carbamates have the same mechanism of action which is ...
inhibition of acetylcholinesterase, causing ach to remain in the synapse leading to excessive firing of the nerves.
name two herbicides
- chlorophenoxy compounds
- paraquat (more acutely toxic)
what are the health effects of fungicides
waste material, usually in chemical form, that can cause long-term risk to environment and health
the collection, transport, processing, recycling, reducing or disposal of waste materials
concerning waste management, communities need to:
understand the risks and controls, ensure good communication
... deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water for the general protection of human health and the environment or from a site intended for development.
what is remediation based on?
assessment of human health and ecological risks and is subject to regulatory requirements
different toxic wastes
- Dioxins - PCDDs (polychlorinated dibenzodioxins)
- PCBs - Polychlorinated biphenyls
a large family of related compounds, which differ in number and position of chlorine atoms
why are dioxins dangerous?
- are not easily broken down in the environment
- accumulate in the soils
- bioaccumulate in fat
- biomagnify as they pass up the food chain
what are the health effects of dioxins?
cancer, immune sys, reprod. and dev. effects
what is the half life of both dioxins and PCBs?
PCBs health effects
- chloracne in workers
- liver damage
abundant man-made chemicals, as plasticizers for PVC
health effects of phtalates
repr. and dev. toxicities
an exogenous substance that alters functions of the endocrine system and consequently causes adverse effects in an organism and its progeny
Endocrine Disrupting Chemicals
mechanisms of endocrine disruption are ...
- acting as receptor agonist
- acting as receptor antagonist
- modifying the metabolism of natural hormones
- modifying the number of hormone receptors
- modifying the production of natural hormones
- modulating hormone levels
EDC important issues
- no threshold - any level
- EDC dose-response relationship is the most controversial issue
- latent adverse effects
name some EDCs
dioxins, PCBs, Phtalates, persticides, phytoestrogens,
naturally occurring polycyclic phenols found in certain plants
benefits of phytoestrogens in...
coronary heart disease, diabetes, osteoporosis, cancer.
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