Environmental Flashcards
- ‘Environmental diseases’ 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
environmental factors.
It has been estimated that in the US work-related injuries occur
2x more frequently than home injuries at an annual cost that exceeds $25 billion.
- US agencies involved in regulating environmental hazards include:
a. Environmental Protection Agency
b. Food and Drug Administration
c. Occupational and Safety Health Administration
d. Consumer Products Safety Commission
- Categories of Environmental Diseases:
a. Air Pollution – outdoor/indoor pollution
b. Industrial Exposures – coal, asbestos, other metals
c. Tobacco Smoke – major public health problem
d. Chemical agents – therapeutic & nontherapeutic drugs
e. Physical agents – mechanical trauma, thermal injury
f. Electrical injury
g. Radiation injury
h. Nutritional diseases
A. General – injuries can occur by
inhalation, ingestion, injection or absorption thru the skin.
Estimated 2 million potentially hazardous exposures each
year in the U.S. most (90%) are unintentional.
- Oral intake accounts for about
73% of exposures
- Children less than
6 yrs account for about 61% of exposures
- Adverse drug events account for about
2%
The most frequent environmental agents are common household items:
cleaning agents, analgesics, cosmetics, plants or cold preparations.
Factors that affect chemical injuries: “CLADME” which stands for:
- Concentration
- Liberation
- Absorption
- Distribution
- Metabolism
- Excretion
A. Injury by Therapeutic Agents – Adverse drug reactions (ADR’s) are common affecting an estimated
7-8% of hospitalized persons and about 10% of these are fatal.
Anaphylaxis can occur with any medication, but is most often associated with
antibiotics (penicillin is the classic).
The more potent the drug – the more likely it is to cause an
adverse reaction – anti-cancer drugs are the best examples.
Some other notable ADR’s:1. Acetaminophen (Tylenol®) – overdose occurs after
large ingestion (15-20 g).
Some other notable ADR’s: Aspirin (Acetylsalicylic acid or ASA) – overdose may be
accidental (young kids) or intentional (adolescents/adults). Ingestion of as little as 2-4 gms (kids) or 10-30 gms (adults) may be fatal.
Tylenol Toxicity is by damage to the
liver which occurs over several hours to days. Early symptoms are non-specific – nausea, vomiting, diarrhea, but will be followed by jaundice and shock as the liver failure progresses. There may also be heart and kidney damage as well.
Aspirin The major acute injury is a
metabolic one – first there is respiratory alkalosis followed by metabolic acidosis.
Aspirin: Chronic ingestion (3 gm or more per day) is associated with
headaches, dizziness, ringing in the ears (tinnitus), drowsiness, mental status changes, gastritis, GI bleeding, nausea and vomiting. It may progress to seizures and coma.
Some other notable ADR’s: 1. Exogenous Estrogens & Oral Contraceptives – until 2002, estrogens were widely used for
postmenopausal syndrome (hormone replacement therapy or HRT) and to prevent or slow progression of osteoporosis.
Estrogens: More recent studies indicate that patients receiving long term HRT are at increased risk for
breast cancer, strokes and blood clots.
Estrogens/oral contraceptives: The benefits of SHORT term therapy
(alleviation of severe peri-menopausal symptoms or prevention of osteoporosis if no other modality is effective) may outweigh these risks.
OCP’s have been in use for
> 30 yrs. Like all medications there are known risks (blood clots, hypertension, hepatic adenoma, cholecystitis, slightly increased risk in breast cancer) and benefits (contraception, protective effect for endometrial and ovarian cancers) to their use.
OCPS: have protective effect for
endometrial and ovarian cancers
A. Injury by Nontherapeutic Agents – the spectrum of agents is quite large ranging from
environmental exposures - lead, carbon monoxide, cleaning agents, cyanide, ethylene glycol, organophosphates (pesticides), mercury, plants (mushrooms), petroleum products and PCB’s to agents that may be ingested for mind/mood altering experiences.
- Lead – lead is found in many places in the environment –
urban air, soil, water, food, house dust, gasoline (historical), batteries, and older paints (lead-based). Exposure to lead also occurs in certain occupations – foundry workers and mining.
Lead has a high affinity for enzymes involved in the synthesis of
hemoglobin which blocks or hinders the incorporation of iron into the molecule.
Lead poisoned patients develop a
microcytic hypochromic anemia.
A majority (80-85%) of absorbed lead is taken up by the
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 in the gums causes
hyperpigmentation.
Lead toxicity in the CNS is most likely to occur in
kids.
A number of neurologic disorders may be seen – ranging from mild deficits to sensory, motor, cognitive and psychologic. Reduced IQ’s and learning disabilities may result.
In adults lead toxicity may lead to
peripheral neuropathies (wristdrop and footdrop).
Lead toxicity in the GU tract is characterized by
severe, poorly localized, “colicky” pain.
Lead is also toxic to the
renal tubules, which may lead to interstitial fibrosis and renal failure.
Monitoring lead exposure is a public health responsibility. The maximum allowable blood lead level was reduced from
10 to 5 ug/dL in 2012.
Lead Treatment is generally by
chelation therapy (starting at 45 ug/dL) and supportive measures.
a. Sedative-hypnotics –
alcohol, barbiturates, benzodiazepines
b. CNS stimulants –
cocaine, amphetamines, weight loss products
c. Opioids –
heroin, morphine, methadone, codeine
d. Cannabinoids –
marijuana
e. Hallucinogens –
LSD, mescaline, phencyclidine (PCP), ketamine
f. Inhalants –
glues, toluene, paint thinner, gasoline, amyl nitrate, nitrous oxide
g. Nonprescription drugs –
atropine, scopolamine, antihistamines, weak analgesics
Club Drugs – a collective term for substances that have become popular in dance clubs, bars, raves or trances. There are a variety of drugs including
methamphetamines (such as MDMA, ecstasy), hallucinogens (LSD, ketamine and, CNS depressants (GHB) and benzodiazepines (Rohypnol).
One of the side effects of MDMA is
bruxism – clenching of teeth. One way of dealing with this is by using a pacifier, reportedly used to store another “hit”.
- Abrasion - a wound produced by
scraping or rubbing leading to removal of a superficial layer of skin
- Contusion –
(bruise) a wound caused by a blunt object, doesn’t break the skin but may lead to damage to blood vessels and extravasation of blood in tissues.
- Laceration –
a tear in tissue – usually with irregular, jagged edges.
- Thermal burns – cause
> 5000 deaths per yr in the US.
Body operates in temperature range of
31o to 41oC (89-106oF)
Hyperthermia (burns) – cause
> 5000 deaths/yr in the US
a. Factors affecting clinical significance of burns
1) percentage of total body surface involved (Rule of 9’s)
- Head & neck 9%, Trunk front 18%, trunk back 18%, Arms 9% each, hands: 1% each, Legs 18% each, Perineum 1 %)
2) depth of the burn (full or partial thickness)
3) possible internal injuries from inhalation of hot gases and fumes
4) the age of the patient
5) how fast & how well is it treated?
b. Clinical consequences of burns:
1) > 50% total body surface involvement is grave 2) shock is frequent with > 30-40% total body surface involvement
a) massive fluid shifts causing hypovolemic shock
c) sepsis/infections – Pseudomonas spp., candida
d) other problems - electrolyte, and nutritional imbalances
3) Internal thermal injury
a) noxious fumes (CO, cyanide)
b) any part of respiratory tract may be damaged
c) delayed - acute respiratory distress syndrome (ARDS)