Path- Environmental Pathology Flashcards
What are the 6 air pollutants that have set National Ambient Air Quality Standards?
Which 2 are the most widespread health threats?
- particles
- ground-level ozone
- carbon monoxide
- lead
- sulfur dioxide
- nitrogen oxides
Particles and ground-level ozone are the most widespread health risks
What is particle pollution?
What size particles have the highest potential for causing health problems?
Particle pollution is a mixture of small particles [ injury.
Describe:
- inhalable coarse particles
- fine particles
in terms of where they are found and what size they are
Inhalable coarse particles:
- found near roadways and dusty industries
- less than 10 but greater than 2.5 micrometers
Fine particles
- smoke from forest fires, power plants, industries, cars
- less than or equal to 2.5 micrometers
What is ground-level ozone?
Ozone in the trophosphere that is harmful [as opposed to ozone in the stratosphere which protects life on earth from the suns rays]
How does ground-level ozone form?
What is the seasonal preference?
Forms by a chemical reaction between nitrogen oxides and volatile organic compound in the presence of HEAT and SUNLIGHT
-motor vehicle exhaust, industrial emission, gasoline vapor, chemical solvents
- Summertime air pollutant
What is the primary constituent of ground-level ozone?
How does this effect our health?
Smog is the major constituent.
03 produces free radicals that injure epithelial cell lining of the respiratory tract and type 1 alveolar cells causing:
- airway irritation, coughing, pain with deep breath
- wheezing during exercise or outdoor activity
- aggravation of asthma,
- increased risk for bronchitis, pneumonia
- permanent damage of lung after repeat exposure
What are the major sources of CO?
- car exhaust
- construction equipment/ boats
- industrial processing [metals and chemicals]
- wood burning [residential]
- natural wood burning [forest fires]
- wood stoves, gas stoves, smoking cigs, unvented space heaters
What is the seasonal preference for high levels of CO in outdoor air? Why?
Colder months because there are “inversion conditions” where air pollution gets trapped near the ground beneath a layer of warm air
How much greater is the Hb affinity for CO over O2?
What levels cause systemic hypoxia?
What levels can cause unconsciousness and death?
200x affinity for CO
20-30% CO –> systemic hypoxia
60-70% CO –> unconsciousness and death
What is the major effect of chronic CO poisoning [low levels but persistent exposure]?
Widespread hypoxic damage to the CNS
- basal ganglia
- lenticular nuclei
What are the major effects of acute CO poisioning [suicide, accidental exposure]?
- cherry-red color of skin and mucous membranes
- brain edema
- punctate hemorrhages
- neuronal death
Sulfur is present in which materials?
When are sulfur oxides formed?
Once sulfur oxide is released into the air, what 2 things can it form?
It is in crude oil, coal and ore.
SO2 is formed when fuel containing sulfur is burned [gas extraction from oil, metal extraction from ore]
-electric utilities, petroleum refinery, cement factory, metal processing plants, large ships
S02 can dissolve with:
- water –> sulfuric acid [acid rain]
- other gases –> sulfate particles
Both sulfuric acid and sulfate particles can cause respiratory problems esp in people with asthma
What is the normal appearance of Nitrogen oxides?
How does the appearance differ when it is NO2?
Nitrogen oxides are highly reactive gases that are ODORLESS and COLORLESS.
However, nitrogen dioxide along with particulates are reddish-brown layer over urban areas
When do nitrogen oxides form?
What are the man made sources?
When fuel is burned at high temperatures [as in combustion process].
-cars, electric utilities, industrial, commercial, residential sources of burn fuels
What are the 4 negative effects of nitrogen oxides?
- react with volatile organic compounds in the heat to make ground-level ozone
- react with other substances to form acids [acid rain]
- react with ammonia and moisture to form nitric acid that damages lungs and worsens emphysema and bronchitis
- react with organic chemicals and ozone to form nitrate radicals, nitroarenes and nitrosamines that can lead to cancer
What were the main sources of lead emissions historically?
What has changed?
Historically:
- cars and trucks
- industrial sources [metal processing]
Now metal processing is the major source over cars because the phasing out of leaded gasoline
What is the most widespread source of lead today for US children?
flaking lead paint from old buildings and soil contamination
Why are children at greater risk of lead toxicity?
- Children absorb over 50% of lead from contaminated food, and adults absorb only 15%
- the BBB is more permeable in children
When lead is absorbed from food, where does it distribute?
- 80-85% is taken up by bones and teeth [20-30yr T1/2]
- 5-10% stay in blood [1 month T1/2]
- remainder goes to soft tissue
What is the effect of lead on pregnancy?
Lead competes with calcium and binds phosphate in the bones.
When a woman is pregnant or lactating, this is a calcium stress and Lead is released into the blood where it can expose the fetus/infant.
- preterm labor
- spontaneous abortion
- low birth weight
- impaired brain development
What enzymes are inhibited by lead?
What is the clinical result of inhibiting these enzymes?
- enzymes with sulfhydryl groups in heme synthesis like aminolevulinic acid, ALA dehydratase, or ferrochelatase
- results in MICROCYTIC, HYPOCHROMIC ANEMIA - Na/K ATPase
- results in HEMOLYTIC ANEMIA
What are the indicators of lead toxicity in the blood?
When ferrochelatase is inhibited there will be elevated blood:
- zinc protoporphyrin
- free RBC protoporphyrin
Lead affects every organ system, but what are the most notable?
- RBCs
- brain/peripheral nerves
- GI
- kidney
- skeleton
What is the most useful screening and diagnostic test for recent or ongoing lead exposure?
venous blood lead concentration {BLC}
What chelating agents are used for lead toxicity?
- Calcium disodium edetate
- dimercaprol
- D-penicillamine
- succimer
What should be done at BLC levels: 1. below 10 2. 10-20 3, 20-44 4. 45-69 5 > 70 OR encephalopathy
- nothing
- retest every 3 months and if elevated:
- follow guidelines or 20 to 44
- lead education
- if a lot of children have it, community poison prevention - retest monthly, clinical eval and chelator of necessary, education, environment intervention
- clinical eval and chelators within 48hrs, retest monthly, education, environment intervention
- medical emergency, hospitalize and chelate immediately, education, intervention
Where does organic mercury [methylmercury] accumulate?
What does it cause in fetuses, infants and children?
It accumulates in fish, shellfish and animals that eat fish.
It can impair neurological development by accumulating in the brain and blocking ion channels
How does elemental mercury [metallic] get into the body?
What does it cause?
It is absorbed through the lungs and causes
A lot of neuro problems like:
- tremors
- emotional changes
- insomnia
- neuromuscular changes [weakness, atrophy]
At higher levels it can also involve renal failure, respiratory failure and death
How does inorganic mercury get into the body?
What does it cause?
It is absorbed in the GI tract and damages:
- GI tract
- nervous system
- kidneys
Skin rash, emotional changes, memory loss, cognitive disturbances, muscle weakness
Where is arsenic found?
What is the pathology?
What would you see with acute toxicity? Chronic?
It is in drinking water in Chile, Bangladesh and China
It interferes with mitochondrial oxidative phosphorylation
Acute:
GI, cardio, CNS–> death
Chronic:
- skin hyperpigmentation, hyperkeratosis
- SCC, BCC
- lung carcinoma
What are the 4 adverse effects of cadmium?
- obstructive lung disease
- renal tubular damage
- osteoporosis
- osteomalacia
What are the negative effects of benzene?
- aplastic anemia
2. AML
What are the negative effects of polycyclic hydrocarbons?
- most potent carcinogens– found in cigarette smoke
1. lung cancer
2. bladder cancer
What are the negative effects of organochlorines?
- anti-estrogen
2. anti-androgen
What are the negative effects of dioxins, polychlorinated biphenyls?
- folliculitis
2. chloaracne - acne, cysts, hyperpigmentation, hyperkeratosis
What are the negative effects of vinyl chloride?
hepatic angiosarcoma
What are the negative effects of mineral dusts?
- pneumoconiosis
2. cancer [asbestos]