Environmental Disease

Environmental Health Issues

• Environmental disease refers to disorders caused by exposure to chemical or physical agents in the ambient, workplace, and personal environments.
• Types of environmental health issues include climate change, toxic agents, lifestyle diseases, physical injury, and nutritional diseases.

Determinants of Health and Climate Change

• Environment and genetics play a role in determining health.
• Some injuries or illnesses are related to exposure to physical or chemical agents in the workplace or living environment.

Health Effects of Climate Change

• Rising atmospheric and ocean temperatures (expected to increase by 2-5°C by 2100) are responsible for climate change.
• Responsible gases include CO2, ozone, and methane, which contribute to the greenhouse effect.
• The greenhouse effect causes gases and water vapor to absorb energy radiated from the earth's surface, leading to climate change.
• Potential health impacts of climate change include:
  • Cardiovascular, cerebrovascular, and respiratory diseases, exacerbated by heat waves and air pollution.
  • Gastroenteritis, cholera, and food and waterborne infectious diseases.
  • Vector-borne diseases, such as malaria, dengue fever, and Lyme disease, which are affected by changes in temperature and vector number and geography.
  • Malnutrition due to changes in climate and disruption of crops.
  • Displacement of people, leading to the spread of disease, social unrest, poverty, and war.

Air Pollution

• Consumption of fossil fuels, including coal and oil burning power plants, industry, and incinerators, contributes to air pollution.
• Outdoor pollutants include ozone, nitrogen dioxide, sulfur dioxide, acid aerosols, particulates, and carbon monoxide.
• Ozone is a major component of the "Air Quality Index" and causes inflammation in the lungs, particularly affecting asthmatics, children, and the elderly.
• High outdoor pollution increases the risk of dying from COVID-19 infection by 15%.

Exposure to Pollutants

• Xenobiotics are exogenous chemicals in the environment that can be absorbed through skin contact, inhalation, or ingestion.
• The cytochrome P-450 system is responsible for detoxifying or converting compounds that cause cell injury.
• Factors determining lung injury include particle size and airway anatomy, concentration and chemical reactivity, duration of exposure, and host clearance mechanisms.

Indoor Air Pollution

• Sources of indoor air pollution include secondhand smoke, wood smoke, asbestos, radon, nitrogen oxides from gas and kerosene stoves, carbon monoxide, and bioaerosols (microorganisms, allergens, dust mites, fungi, and mold).

Carbon Monoxide

• Carbon monoxide is an air pollutant that binds to hemoglobin, leading to systemic hypoxia and asphyxiation.
• Carbon monoxide poisoning can cause CNS depression, and accidental or intentional death.
• Diagnosis involves detecting high levels of carboxy-hemoglobin in the blood.
• Acute poisoning can cause cherry-red coloring of skin and mucus membranes due to carboxy-hemoglobin, leading to hypoxia-ischemia.
• Chronic poisoning can cause persistent low levels of CO, leading to chronic hypoxia and irreversible neurological changes.

Chemical Injuries

• 2 million exposures/year in the US, with children accounting for over 60%

Lead Poisoning

• Found in urban air, soil, water, food, house dust, batteries, and older paints
• 85% of lead is taken up by bones and developing teeth, competing with calcium
• Causes anemia (microcytic, hypochromic), neurologic disturbances, and wrist/foot drop
• Gingival hyperpigmentation ("lead line") and radiographic evidence of lead exposure
• Interferes with calcium metabolism, causing chronic anemia and CNS problems in children
• GI tract symptoms include colicky pain, while kidney damage can lead to renal failure
• CDC guidelines: Pb threshold blood level for concern > 5 μg/dL, with chelation therapy initiated at > 45 μg/dL

Toxic Effects of Heavy Metals

• Lead: CNS, anemia, others
• Mercury: contaminated fish, causes cerebral palsy, deafness, and blindness in fetus; "Mad Hatter" in adults
• Arsenic: neuropathy, keratotic papules, skin cancer
• Cadmium: obstructive lung disease, kidney damage

Effects of Tobacco

• Most common exogenous cause of cancer, responsible for 90% of lung cancers
• Causes oral cancer, atherosclerosis, and passive smoking
• Maternal smoking: abortion, preterm birth, growth retardation
• Smoking cannabis and e-vaping have similar components, but uncertain carcinogenesis

Drugs of Abuse

• Sedative-hypnotic: EtOH, barbiturates, benzodiazepines
• CNS Stimulants: cocaine, amphetamines
• Opioids: heroin, morphine, methadone, codeine, fentanyl
• Hallucinogens: LSD, PCP, mescaline, MDMA
• Inhalants: glue, toluene, paint thinner, gasoline, amyl nitrate, nitrous oxide
• Nonprescription drugs: analgesics, antihistamines, scopolamine, atropine

Effects of Alcohol

• 14.4 million adults in the US have AUD
• Toxic effects: alcohol oxidation, acetaldehyde toxicity, endotoxin release, and liver damage
• Liver damage: hepatitis, cirrhosis; GI: gastritis, ulcers, varices
• Neurologic: cerebral atrophy, degeneration; CV: cardiomyopathy, hypertension
• Pancreatitis, carcinogenesis, malnutrition (thiamine, pyridoxine, folate, vit A deficiencies), and fetal alcohol syndrome

Meth Mouth and Skin Sores

• Severe dental caries, xerostomia, and periodontal disease

Cocaine Use

• Cardiovascular: HTN, MI, stroke; CNS: hyperthermia, brain atrophy
• Fetal effects: hypoxia, miscarriage, impaired brain development
• Oral effects: mucosal burns, perforation of palate, nasal septum, and dental neglect

Injury by Therapeutic Agents

• Adverse drug reactions (ADRs) common (2%), with relatively minor ADRs (rashes, GI upset, xerostomia)
• Major ADRs: anaphylaxis (penicillin), blood clots, arrhythmias, hematologic disorders, and hepatitis
• Potency-related ADRs, especially with anti-cancer medications
• Aspirin OD: bleeding/bruising tendency at chronic doses; acetaminophen OD: liver necrosis, liver failure/death

Toxic Effects of Heavy Metals

• Lead affects the Central Nervous System (CNS) and causes anemia
• Mercury contamination through fish consumption causes cerebral palsy, deafness, and blindness in fetuses, and "Mad Hatter" syndrome in adults
• Arsenic exposure leads to neuropathy, keratotic papules, and skin cancer
• Cadmium causes obstructive lung disease and kidney damage

Effects of Tobacco

• Tobacco is the most common exogenous cause of cancer
• It is responsible for 90% of lung cancers and is the most common cause of oral cancer
• Smoking is the most important cause of preventable deaths
• Smoking cannabis and e-vaping have similar adverse effects, including oral and pulmonary disease, although the carcinogenic effects are unclear

Adverse Effects of Tobacco

• Direct irritant effect on tracheobronchial mucosa
• Carcinogenesis: polycyclic hydrocarbons, nitrosamines
• Atherosclerosis
• Passive smoking
• Maternal smoking: abortion, preterm birth, growth retardation

Drugs of Abuse

• Sedative-hypnotic drugs: EtOH, barbiturates, benzodiazepines
• CNS Stimulants: cocaine, amphetamines
• Opioids: heroin, morphine, methadone, codeine, fentanyl
• Hallucinogens: LSD, PCP, mescaline, MDMA
• Inhalants: glue, toluene, paint thinner, gasoline, amyl nitrate, nitrous oxide
• Nonprescription drugs: analgesics, antihistamines, scopolamine, atropine

Effects of Alcohol

• 1 in 8 adults in the US (14.4M) have Alcohol Use Disorder (AUD)
• 100,000 deaths per year are attributed to alcohol-related causes
• Toxic effects of alcohol include:
  • Fat accumulation in the liver due to alcohol oxidation
  • Acetaldehyde toxicity, which leads to genetic variation in metabolism
  • Increased ROS, causing lipid peroxidation of membranes
  • Endotoxin release, leading to increased TNF and cytokines from macrophages, causing liver damage

Alcohol Use Disorder

• Liver: hepatitis, cirrhosis
• GI: gastritis, ulcers, varices
• Neurologic: cerebral atrophy, degeneration
• CV: cardiomyopathy, hypertension
• Pancreatitis
• Carcinogenesis
• Malnutrition: thiamine, pyridoxine, folate, and vitamin A deficiencies
• Fetal alcohol syndrome

Methamphetamine Abuse

• Severe dental caries
• Xerostomia
• Periodontal disease

Cocaine Use

• Addictive psychostimulant
• Cardiovascular: hypertension, MI, stroke
• CNS: hyperthermia, brain atrophy
• Fetus: hypoxia, miscarriage, impaired brain development
• Oral: mucosal burns, perforation of palate, nasal septum, and dental neglect

Injury by Therapeutic Agents

• Adverse drug reactions (ADR) are common (2%)
• Relatively minor ADRs: rashes, GI upset, xerostomia
• Major ADRs: anaphylaxis, blood clots, arrhythmias, hematologic disorders (anemia, thrombocytopenia, leukopenia), hepatitis
• ADRs are also related to potency, especially with anti-cancer medications

Aspirin and Acetaminophen Overdose

• Aspirin overdose: accidental (children) or intentional (adolescents and adults) with high doses (3-4g) that can be fatal
• Bleeding/bruising tendency at chronic doses
• Acetaminophen overdose: causes liver necrosis and may result in liver failure/death
• In the US, acetaminophen toxicity accounts for 50% of acute liver failure and is a common cause of transplantation

Drugs of Abuse (Non-therapeutic)

• Sedative-hypnotic drugs include Ethanol (EtOH), barbiturates, and benzodiazepines
• CNS Stimulants include cocaine and amphetamines

Opioids

• Opioids include heroin, morphine, methadone, codeine, and fentanyl

Hallucinogens

• Hallucinogens include LSD, PCP, mescaline, and MDMA

Inhalants

• Inhalants include glue, toluene, paint thinner, gasoline, amyl nitrate, and nitrous oxide

Nonprescription drugs

• Nonprescription drugs include analgesics, antihistamines, scopolamine, and atropine

Physical Agents

• Mechanical trauma can cause abrasions, contusions, lacerations, incisions, and puncture wounds.
• Thermal injuries occur when the body is exposed to temperatures outside the normal range of 31°C to 41°C (89-106°F).
• Hyperthermia (burns) cause over 5000 deaths per year in the US, while hypothermia is caused by prolonged exposure to low temperatures.

Types of Injuries

• Abrasion: removal of surface layers by scraping or rubbing.
• Contusion: rupture of small blood vessels with extravasation of blood into tissues, also known as a bruise.
• Laceration: inflicted by a blunt object resulting in a ragged tear with tissue bridging.
• Incision: inflicted by a sharp instrument.
• Puncture wound: caused by a long narrow instrument, such as a pencil or toothbrush.

Electrical Injuries

• Electrical injuries can cause burns, ventricular fibrillation or cardiac and respiratory center standstill.
• Severity of electrical injuries depends on current (amperage) and path through the body.
• Low voltage exposure typically occurs through wiring at home or work, while high voltage exposure typically occurs through high-power lines or lightning.

Abnormal/Pathologic Scars

• Excess scar formation can result in hypertrophic scars, keloids, and contracture.
• Hypertrophic scars: raised scars that grow beyond the boundaries of the injury, but eventually regress.
• Keloids: raised scars that grow beyond the boundaries of the injury, but do not remodel, contract, or regress.
• Contracture: deformity especially around joints, resulting in restricted movement.

Burns

• Important factors to consider when evaluating burns include:
  • Percentage of body surface area affected (rule of 9's)
  • Depth of burn (full or partial thickness)
  • Age of patient (elderly and very young are more susceptible to complications)
  • Speed and quality of treatment

Thermal Burns

• First degree burns: focal necrosis of epidermis, characterized by serous inflammation.
• Second degree burns: necrosis of epidermis and upper dermis, with skin appendages spared.

Environmental Health Issues

• Environmental disease refers to disorders caused by exposure to chemical or physical agents in the ambient, workplace, and personal environments, including diseases of nutritional origin.

Determinants of Health and Climate Change

• Environment and Genetics play a role in health issues.
• Some injuries or illnesses are related to exposure to physical or chemical agents in the workplace or living environment.

Health Effects of Climate Change

• Rising atmospheric and ocean temperatures (2-5°C by 2100) are responsible for various health issues.
• Gases responsible for climate change: CO2, ozone, methane, and water vapor.
• Greenhouse effect: gases and water vapor absorb energy radiated from the earth's surface, leading to heat retention.
• Potential health impacts:
  • Cardiovascular, cerebrovascular, and respiratory diseases exacerbated by heat waves and air pollution.
  • Gastroenteritis, cholera, and food and waterborne infectious diseases.
  • Vector-borne diseases (e.g., malaria, dengue fever) affected by changes in temperature and vector geography.
  • Malnutrition due to climate-related crop disruptions.
  • Displacement of people, leading to the spread of disease, social unrest, poverty, and war.

Consumption of Fossil Fuels

• Burning fossil fuels (not just cars) contributes to outdoor pollutants.
• Sources of outdoor pollutants:
  • Coal and oil burning power plants.
  • Industry and incinerators.
• Outdoor pollutants:
  • Ozone (causes inflammation in the lungs, especially for asthmatics, children, and the elderly).
  • Nitrogen dioxide.
  • Sulfur dioxide.
  • Acid aerosols.
  • Particulates.
  • Carbon monoxide.
• High outdoor pollution increases the risk of dying from COVID-19 infection by 15%.

Exposure to Pollutants

• Xenobiotics: exogenous chemicals in the environment.
• Exposure routes:
  • Skin contact.
  • Inhalation.
  • Ingestion.
• Cytochrome P-450 system: detoxifies or converts compounds that cause cell injury.
• Factors determining lung injury:
  • Particle size and airway anatomy.
  • Concentration and chemical reactivity.
  • Duration of exposure.
  • Host clearance mechanisms.

Indoor Air Pollution

• Sources of indoor air pollution:
  • Secondhand smoke.
  • Wood smoke.
  • Asbestos.
  • Radon.
  • Nitrogen oxides (from gas and kerosene stoves).
  • Carbon monoxide.
  • Bioaerosols (microorganisms, allergens, dust mites, fungi, mold).

Carbon Monoxide

• Air pollutant.
• Binds to hemoglobin.
• Causes systemic hypoxia.
• Leads to systemic asphyxiation.
• Prevents oxygen transport.
• Causes CNS depression.
• Can lead to accidental or intentional death.
• Diagnosed by high levels of carboxy-hemoglobin in the blood.

Injury from Chemical Agents

• Occurs through inhalation, ingestion, injection, or absorption through the skin.
• Estimated 2 million exposures per year in the US.
• Children account for over 60% of exposures.
• Common sources of chemical agents:
  • Cleaners.
  • Analgesics.
  • Cosmetics.
  • Plants.
  • Cold medications.

Lead

• Found in urban air, soil, water, food, house dust, batteries, and older paints and gasoline.
• Occupational lead exposure: mining, foundries.
• 85% of Pb is taken up by bones and developing teeth, competing with Ca++ and interfering with remodeling process.
• "Lead lines" on radiographs.
• Gingival hyperpigmentation ("lead line").
• Teeth can document lead exposure.
• Pb competes with Ca++ in children.

Toxic Effects of Heavy Metals

• Lead: CNS, anemia, and others.
• Mercury: contaminated fish, causes cerebral palsy, deadness, and blindness in the fetus; "Mad Hatter" in adults.
• Arsenic: neuropathy, keratotic papules, and skin cancer.
• Cadmium: obstructive lung disease and kidney damage.

Effects of Tobacco

• Most common exogenous cause of cancer.
• Responsible for 90% of lung cancers and most common cause of oral cancer.
• Smoking: most important cause of preventable deaths.
• Adverse effects:
  • Direct irritant effect on tracheobronchial mucosa.
  • Carcinogenesis: polycyclic hydrocarbons, nitrosamines.
  • Atherosclerosis.
  • Passive smoking.
  • Maternal smoking: abortion, preterm birth, growth retardation.

Drugs of Abuse (Non-therapeutic)

• Sedative-hypnotic: EtOH, barbiturates, benzodiazepines.
• CNS Stimulants: cocaine, amphetamines.
• Opioids: heroin, morphine, methadone, codeine, fentanyl.
• Hallucinogens: LSD, PCP, mescaline, MDMA.
• Inhalants: glue, toluene, paint thinner, gasoline, amyl nitrate, nitrous oxide.
• Nonprescription drugs: analgesics, antihistamines, scopolamine, atropine.

Effects of Alcohol

• Majority of adults drink.
• 1 in 8 adults in the US have AUD (alcohol use disorder).
• 100,000 die per year from alcohol-related causes.
• Toxic effects:
  • Alcohol oxidation: fat accumulation in the liver.
  • Acetaldehyde toxicity: genetic variation in metabolism.
  • ROS↑: causes lipid peroxidation of membranes.
  • Endotoxin release: ↑ TNF, cytokines from macrophages.
  • Liver damage.

Injury by Therapeutic Agents

• Adverse drug reactions (ADRs) are common (2%).
• Relatively minor ADRs: rashes, GI upset, xerostomia.
• Major ADRs: anaphylaxis, blood clots, arrhythmias, hematologic disorders, and hepatitis.

Physical Agents

• Mechanical trauma: abrasions, contusions, lacerations, incisions, puncture wounds.
• Thermal injuries: body operates in a temperature range of 31°C to 41°C (89-106°F).
• Hyperthermia: causes > 5000 deaths per year in the US.
• Hypothermia: due to prolonged exposure to low temperatures.
• Electrical injury: causes burns, ventricular fibrillation, and cardiac and respiratory center standstill.

Abnormal/Pathologic Scar

• Excess/exuberant scar formation.
• Exuberant granulation tissue.
• Variants: hypertrophic scar, keloid, and contracture.
• Deformity: especially around joints.
• Recent scar: electrical burn scar.