Download Environmental pathology lec.1

lec.1 2014-2015
Environmental pathology
Environmental and Nutritional Diseases
The term “environment” encompasses the outdoor, indoor, and occupational
environments shared by small and large populations, and our own personal
environment. In each of these environments, the air we collectively breathe, the food
and water we consume, and exposure to toxic agents are major determinants of our
health. Our personal environment is greatly influenced by tobacco use, alcohol
ingestion, therapeutic and nontherapeutic drug consumption, and diet. Factors in the
personal environment may have a larger effect on human health than the ambient
environment. The term environmental disease refers to conditions caused by
exposure to chemical or physical agents in the ambient, workplace, and personal
environment, including diseases of nutritional origin.
Effects of Tobacco
Effects of Tobacco
Indeed, tobacco use is the most common exogenous cause of human malignancy,
responsible for 90% of lung cancers. Within 5 years of smoking cessation, overall
mortality, and—more specifically—risk of death from cardiovascular disease is
markedly reduced. Lung cancer risk decreases by 21% within 5 years, but the excess
risk persists for 30 years.
Smoking and Lung Cancer
Polycyclic hydrocarbons, benzopyrene, and nitrosamines in cigarette smoke are
potent carcinogens. Cancer risk is dose related (more cigarettes increases risk), and
smoking synergizes with other carcinogenic influences in causing lung carcinoma
(e.g., asbestos or radiation exposures).
1
lec.1 2014-2015
Environmental pathology
Smoking and Other Diseases
 Formaldehyde, phenol, and nitrogen oxides in cigarette smoke are directly
irritating, inducing tracheobronchial inflammation and increased mucus
output (bronchitis); leukocyte recruitment leads to increased elastase
production and subsequent emphysema.
 Cigarette smoking is strongly linked to development of atherosclerosis and
myocardial infarction; increased platelet aggregation
 Maternal smoking causes fetal hypoxia with intrauterine growth retardation,
and it increases the risk of spontaneous abortions and preterm births.
 Second-hand smoke (environmental smoke) also increases the risk of lung
cancer, ischemic heart disease, and acute myocardial infarction; relative risk
of lung cancer in non-smokers exposed to second-hand smoke is 1.3 times
greater than in individuals not exposed to environmental smoke.
Effects of Alcohol
Adverse alcohol effects are due to:
Acute alcohol injury including hepatic steatosis (fatty change), gastritis and
ulceration, and the depression of CNS activity.
Chronic alcoholism affecting virtually all organs, with substantial morbidity and
mortality:
 Liver: The liver is the main site of injury; besides fatty change, alcoholic
hepatitis and cirrhosis can result . Cirrhosis is associated with portal
hypertension and increased risk of hepatocellular carcinoma.
2
lec.1 2014-2015
Environmental pathology
 Gastrointestinal tract: Massive bleeding may result from acute gastritis and
ulceration or as a consequence of esophageal varices due to portal
hypertension.
 Nervous system: Thiamine deficiency (due to poor nutrition) is common in
chronic alcoholics; it causes peripheral neuropathies and the WernickeKorsakoff syndrome , as well as cerebral atrophy, cerebellar degeneration, and
optic neuropathy.
 Cardiovascular system: Chronic alcoholism can cause a dilated
cardiomyopathy and is associated with an increased incidence of
hypertension. Liver injury due to alcohol excess reduces HDL production and
increase cardiovascular risk.
 Pancreas: Alcohol use increases the risk of acute and chronic pancreatitis.
Ethanol and cancer: Alcohol use is associated with increased cancer rates in the
oral cavity, pharynx, esophagus, liver, and possibly breast. The acetaldehyde
metabolite may act as a tumor promoter.
3