Lecture 9 - Environmental Diseases Flashcards
what do ‘environmental diseases’ refer to?
it refers to injuries or disorders that are caused by chemical or physical agents
- a related field, occupational medicine, focuses on injuries that occur in the workplace from these same factors
- In US work related injuries occur 2X more frequently than home injuries at an annual cost exceeding 25 billion
Us agencies involved in regulating environmental hazards include:
- environmental protection agency
- food and drug administration
- occupational and safety health administration
- consumer products safety comminssion
what are the categories of environmental diseases
- air pollution - indoor/ outdoor pollution
- industrial exposures - coal, asbestos, other metals
- tobacco smoke - major public health problem
- chemical agents - mechanical trauma, thermal injury
- electrical injury
- radiation injury
- nutritional diseases
how do injuries occur from chemical agents?
inhalation, ingestion, injection or absorption through the skin
- 2 million exposures in US evert year
- 90% unintentional
oral intake accounts for what percent of exposures?
73% of exposures
children less than 6 years account for what percent of exposures?
61% of exposures
adverse drugs account for what percent of exposures?
2% of exposures
what are the most frequent chemical agents that cause injury?
common household items: cleaning agents, analgesics, cosmetics, plants or cold preparations
what does CLADME stand for?
They are factors that affect chemical injuries
Concentration Liberation Absorption Distribution Metabolism Excretion
adverse drug rxs are common affecting 7-8% of hospitalized persons and 10% of these are fatal. Anaphylaxis can occur with any medication, but it is more often associated with which class of drug?
antibiotics (pennicillin is the classic)
the more potent the drug - the more likely it is..
to cause an adverse rxn
anti-cancer drugs are the best examples
aspirin (ASA) overdose can be acciental (young kids) or intentional (adults). what gm amount is fatal in kids and what in adults?
kids - 2-4 gms
adults - 10-30 gm
with aspirin the major acute injury is….
metabolic one - first there is respiratory alkalosis followed by metabolic acidosis
chronic ingestion (3 gm or more per day) is associated with what side effects?
headaches dizziness ringing in the ears (tinnitus) drowsiness mental status changes gastritis GI bleeding nausea vommiting *it may even progress into seizures and come
what g amount causes overdose in acetaminophen
overdose occurs after large ingestion (15-20 g)
what is the toxicity and side effects associated with acetaminophen?
toxicity: liver damage (over several hours to days)
early symptoms: nausea, vomiting, diarrhea - then following by jaundice and shock as the liver failure progresses
*There might also be heart and kidney damage as well
exogenous estrogens and oral contraceptives if pts are receiving long term hormone replacement therapy are at an increased risk for:
breast cancer, strokes and blood clots
- The benefits of SHORT term therapy ( s/a alleviation of severe peri-menopausal symptoms or prevention of osteoporosis if no other modality is effective) may outweigh these risks
what are some risks and some benefits of oral contraceptives?
risks - blood clots, hypertension, hepatic adenoma, cholecystitis, slightly increased risk in breast cancer)
benefits - contraception, protective effect for endometrial and ovarian cancers
what are some examples of nontherapeutic agents?
environmental exposures: lead, carbon monoxide, cleaning agents, cyanide, ethylene glycol, organophosphates (pesticides), mercury, plants (mushrooms) petroleum products
also_ agents that may be ingested for mind/ mood altering experiences
where is lead found in the environment and which type have occupations have an increased risk?
environment - urban air, soil, water, food, house dust, gasoline (historical), batteries, old paints
occupations - foundry workers and mining
lead has high affinity for enzymes involved in the synthesis of hemoglobin which blocks or hinders the incorporation of….
iron into the molecule
which type of anemia can patients develop from lead exposure?
microcytic hypochromic anemia
ughhhhh more anemiaaaa
which part of the body is the majority (80-85%) of absorbed lead taken up?
bones and teeth
- lead competes with calcium and interferes with the normal remodeling process
- bone becomes hyperdense with changes (lead lines) visible on x-rays
lead deposits int he gums causes…
hyperpigmentation
lead toxicity in the CNS is more likely to occur in which age group?
kids
which type or neurologic disorders may be seen with lead exposures?
mind deficits to sensory, motor, cognitive and psychologic
*reduced IQ’s and disabilities may result
in adults, lead toxicity may lead to…
peripheral neuropathies (wristdrop and footdrop)
lead toxicity in the GU tract is characterized by what?
severe, poorly localized, “colicky pain”
*lead is also toxic in renal tubules which may ead to intersitial fibrosis and renal failure
the maximum allowable blood level was reduced from ___ to ___ ug/dL in 2012.
What is the treatment for lead posioning
reduced from 10 to 5 ug/dL
treatment is chelation therapy (startign at 45 ug/dL) and supportive measures
what are the general classes of drugs of abuse? (7 of them)
- sedative-hypnotics - alcohol, barbiturates, benzodiazepines
- CNS stimulants - cocaine, amphetamines,weight loss products
- opioids - heroine, morphine, methadone, codeine
- cannabinoids - marijuana
- hallucinogens - LSD, mescaline, phencyclidine (PCP), ketamine
- inhalants - glues, toluene, paint thinner, gasoline, amyl nitrate, nitrous oxide
- nonprescription drugs - atropine, scopolamine, antihistamines, weak analgesics
what are some examples of “club drugs”
methamphetamines (MDMA, ecstasy)
hallucinogens (LSD, ketamine and CNS depressants and benzodiazepines)
what is a side of effect of MDMA that we will directly see as dentists
bruxism - clenching of the teeth
*they use pacifiers to avoid this while at the same time storing another “hit”
in terms of mechanical injury, what is the definition of abrasion?
a wound produced by scraping or rubbing leading to removal of a superficial layer of skin
in terms of mechanical injury what is the definition of contusion?
bruise, a wound caused by a blunt object, doesnt break the skin but may lead to damage of blood vessels and extravasation of blood in tissues
definition of laceration
a tear in tissue - usually with irregular jagged edges
what are factors affecting clinical significance of burns?
5 of them
- % if total body surface involved (rule of 9’s)
- depth of the burn (full or partial thickness)
- possible internal injuries from inhalation of hot gases and fumes
- age of the patient
- how fast and how well is it treated?
what are the clinical consequences of burns?
- more than 50% total body surface involvement is grave
- Shock is frequent with more than 30-40% total body surface involvement (massive fluid shifts causing hypovolemic shock, sepsis/infections such as pseudomonas candida, and other problems s/a electrolyte and nutritional imbalances)
- Internal thermal injury (nitrous fumes CO, cyanide, any part of resp tract may be damaged, also delayed - acute resp distress syndrome (ARDS))
in terms of hyperthermia what are heat cramps
vigorous exercise with loss of fluid and electrolytes (sweat)
in terms of hyperthermia what is heat exhaustion?
most common, failure of the CV system to adjust to hypovolemia
sudden onset, collapse, usually recover
in terms of hyperthermia what is a heat stroke?
abnormal elevation of the body temperature above 40 deg C, regulatory mechanism fail and the body core temperature rises
- peripheral vasodilation causes “pooling” and decreased circulating blood volume
- tissue become ischemic, necrosis of the muscle and heart may lead to disseminated intravascular coagulation (DIC)
- hight mortality rate especially in elderly and persons under severe physical stress (athletes)
what is hypothermia?
local chilling or freezing of cells and tissues: rate dependent
- direct effects due to crystallization of water
indirect effects due to circulatory changes, trench foot gangrene
what are some systemic reactions of hypothermia?
disorientation, including paradoxical undressing
what are some sources of radiation?
cosmic rays ultraviolet light elements in earths crust (e.g. radon) medical (diagnostic and therapeutic) industrial products nuclear power plants nuclear weapons `
what are some forms of radiation?
electomagnetic waves (xrays and gamma waves) high energy neutrons and charges particles (alpha and beta particles, protons)
what is the mechanism of injury for radiation injury?
- Radiation interactions with atoms and molecules by excitation and ionization
- Interacts with biological systems in the following ways: target effect (direct hit on DNA, causing mutations) and indirect effect (production of free radicals that interact with membranes, nucleic acids and enzymes)
- results may be reversible, cell death (apoptosis) or mitotic arrest, nuclear abnormalities, DNA strand breaks which could lead to latent long term effects - cytoplasm is also effected - swelling, changes in membranes, mitochondria and ER)
how does radition injury affect the skin?
changes occur over time
- erythema (redness) at 2-3 days,
- edema (2-3 weeks)
- blistering and desquamation (4-6 weeks)
- atrophy and cancers (months to years)
what organ systems are extremely susceptible to radiation injury?
hematopoietic and lymphoid
- lymphocytes decrease in hours and rebound in weeks to months
- lymph nodes and spleen shrink in size
- granulocytes decrease over 1-2 weeks and rebound in 2-3 months (PTS ARE SUSCEPTIBLE TO INFECTIONS AT THIS TIME)
- platelets and erythrocytes fall still later and have even more delayed recovery periods (erythrocytes resistant, but precursors are vulnerable)
gonads of both sexes are sensitive and event possible sterility to radiation damage. What about the uterus and cervix?
the uterus and cervix are resistant
why are the lungs sensitive to radiation injury?
b/c of the rich vascularity
-endothelial changes, pulmonary congestion and edema, ARDS, alveolar-capillary block
what can happen to the GI tract if it is exposed to radiation injury?
Gi is very sensitive, it can get ulcers, strictures and later possible carcinomas
blood vessels exposed to radiation first have endothelial injury then later may become…
fibrotic and narrow
even small amount of radiation to the whole body can be devastating. the lethal range for humans begins about __ Sv; at __ Sv death is certain w/o medical are (even then mortality is high)
lethal range begins at 2 Sv
10 Sv death is certain
what is the fatal acute radiation syndrome in reference to hematopoietic?
2-10 Sv
GI symptoms, decreased WBC, platelets, and anemia
- resultant sepsis and bleeding problems
-death in 2-6 weeks
what is the fatal acute radiation syndrome in reference to gastrointestinal?
10-20 Sv
-sever Gi symptoms, bloody diarrhea, producing dehydration, shock, sepsis and death in 5-14 days
what is the fatal acute radiation syndrome in reference to cerebral
more than 50 Sv
listlessness, followed by seizures, come and death in 1-4 hours
what are some general aspects of nutritional diseases?
nutrition is a branch of science that studies the qualitative and quantitive aspects of the diet and utilization of the components required to sustain health
an adequate diet is one that should provide what?
- sufficient CHO’s, protein and fats for the daily metabolic needs
- Essential amino acids and fatty acids for synthesis of structural and functional proteins and lipids
- vitamins and minerals (coenzymes or hormones)
what is primary malnutrition?
diet is deficient in 1 or more components
what is secondary malnutrition?
supply is adequate but there my be a problem with the storage, utilization, excessive losses or drug effects
what are common causes of poor diets?
poverty
ignorance of dietary needs
fad diets
acute illness which raises the basal metabolic rate (burns)
self imposed diet restriction/ habits (anorexia nervosa, bulimia)
malabsorption syndromes
genetic diseases (impair ability to use properly)
what are the 2 protein compartments in the body?
- somatic protein compartment - skeletal muscles - can assess loss of this compartment by measuring skinfold thickness
- visceral protein compartment - mainly the liver, can assess this compartment by measuring serum proteins (albumin, transferrin)
what are the 2 major disorders in which the intake of protein and/ or calories is inadequate?
marasmus and kwashiokor
what is marasmus?
- deficiency of caloric intake
- this results in growth retardation and loss of muscle mass as the body catabolizes protein (amino acid) as a source of energy
- the somatic protein compartment is depleted
- subcutaneous fat is also broken down
- extremities are emaciated
- other manifestations include: anemia and immune deficiency, especially the T cell mediated immune system
- when weight falls to 60% of normal the child has marasmus
what is a common finding and an indictor of immune system deficits?
thrush
- body temperature may be decreased and the pulse may be slow
what is kwashiorkor?
greater deficiency of protein than total calories
- most common form of PEM found in africa, also found in SE Asia
- it is MORE SEVERE than marasmus
- loss of the visceral protein compartment
- decreased albumin causes a loss of vascular oncotic pressure and generalized fluid retention and edema may result (which can mask the true extent of the weight loss)
- kids will classically gave skin changes (hyperpigmentation, desquamation and hypopigmenation - a “flaky paint appearance, hair changes, fatty liver, vitamin and immune deficiencies also occur
- common in 3rd world countries and high mortality in kids less than 5 years old
- secondary forms of PEM can be seen in chronically ill/ hospitalized patients (even in the US)
what is cachexia
a form of wasting that is encountered in cancer patients
- probably results from decreased intake (loss of appetite) as well as an increase in catabolism (cytokine-mediated)
vitamin deficiencies are common in people in lower SES and are usually a part of general malnutrition. What are some examples or primary and what are some examples of secondary?
primary - insufficient diet
secondary - problem with absorption, transport, storage, utilization, metabolism, etc
vitamins are divided into two categories, what are they?
fat soluble (A, D, E, K) and water soluble
fat soluble vitamins need healthy intestinal mucosa, bile and pancreatic secretions for proper _______
absorption
In chronic malabsorption states (inflam. bowel disease) and in alcoholic liver disease the absorption of fat soluble vitamins will be….
poor
*But, b/c of lipid solubility, these vitamins can easily be stored and deficiency usually develops slowly
vitamin A has been found to prevent what condition?
night blindness
vitamin A is made up of 3 biologically active forms, what are they?
retinol
retinal
and retinoic acid
in what foods can vitamin A be found?
yellow and leafy green vegetables
some animal products (fish, liver, eggs, milk, and butter
over 90% of vitamin A is stored in the _____, where there are reserves for ______
liver
reserves for 6-12 months
when needed retinol is released by the lier and is bound to a ____ ____
carrier protein (retinol-binding protein)
what are the 3 functions of vitamin A?
- maintain normal vision in reduced light
- Augments differentiation of specialized epithelial cells (mucus secreting)
- enhance immunity to infections, esp. in children
if there is a deficiency in vitamin A what will be the clinical signs?
- early sign - impaired vision at night
if persists - dryness of the conjunctiva (xerosis), the mucosa of the lacrimal glands will be replaced by keratinized epithlium and keratin debris may accumulate
furthermore - drying may lead to damage to the cornea and total blindness is possible - In addition to the ocular changes the epith. of the respiratory and urinary tracts may undergo squamous metaplasia - this will predispose to infections
- The immune system is also affected - common infections s/a measles, pneumonia and infectious diarrhea may result
what toxic result (symptoms) can happen if you ingest too much vitamin A?
25,000 IU of more can result from over use of vitamin supplements and rarely from using topical retinoids (for acne)
- infants are especially susceptible to toxicity
- symptoms of acute toxicity = nausea, vomitting, irritability, headache, blurred vision (papilledema)
symptoms of chronic toxicity = anorexia, hair loss, dry skin, pruritis, dry mucous membranes, fissured lips, fatigue, weight loss, bone and joint pain
vitamin C has been shown to prevent what condition
scurvy
what kind of vitamin is it and what founds is it found in?
it is an essential vitamin (we cannot synthesize it)
it is found in citrus fruits, vegetables (tomatoes, g. peppers, cabbage, leafy greens, potatoes), also in milk and some animal problems
*Ascorbic acid is heat labile so fresh and uncooked foods have highest content
what groups is scurvy commonly found in?
in the elderly, in alcoholics or anyone with erratic eating habits (fad foods can be a cause)
also at risk are peritoneal dialysis and hemodialysis patients and infants who are fed evaporated milk formula that isn’t fortified with vitamin C
what are the 3 functions of vitamin C?
- formation and stabilization of collagen
- conversion of tyrosine to catecholamines
- role as an antioxidant
what is scurvy
disease of impaired collagen synthesis
- weakened collagen doesnt support the walls of capillaries and venules - hemorrhages are a common finding in the skin and gingival mucosa
- other sites for bleeding - joints (hemarthrosis), behind the eye, subarachnoid space, and within the brain (can be fatal)
- skeletal changes are found in infants and kids - insufficient production of osteoid matrix resulting in cartilaginous overgrowth, bowing of the long bones (esp. the legs), depression of the sternum
- wound healing is also impaired (b/c it needs collagen) and ability to localize infections is impaired
-anemia (b/c of bleeding and iron deficiency) is common
man, anemia is everywhere these days
what clinical symptoms of scurvy are present in the mouth?
gingival bleeding, swelling and periodontal infections
what happens if you have too much vitamin C?
excessive ingestion ( more than 2 g/d)
- idea that vitamin C prevents colds has not been established
- some protection from gastric and esophageal cancers has been reported
- large daily ingestions can enhance iron absorption which would create iron overload in susceptible persons
*Conversely is a person abruptly ceases taking megadoses they may precipitate “rebound scurvy” b/c of enhanced clearance mechanisms
how is vitamin C excreted?
in the urine, ingesting large doses will acidify the urine which may increase risk for stone formation
