Heavy Metals as Environmental Pollutants

Chapter 4: Cellular Biology This chapter explores altered cellular and tissue biology, focusing on cellular adaptation, injury, manifestations of cellular injury, cellular death, aging, and the various types of cell death such as necrosis and apoptosis. Cellular adaptation allows cells to respond to physiological and pathological conditions, but severe or prolonged stressors can lead to cellular injury or death. Common sources of cell injury include lack of oxygen, free radicals, infections, inflammation, and metabolic derangements. Cellular aging also contributes to changes in structure and function. Bullet points Heroin ● Highly addictive opioid closely related to morphine, methadone, and codeine ● Withdrawal causes intense fear ● Sold "cut" with similar-looking white powder, often highly contaminated ● Injecting can lead to infectious complications, including Staphylococcus aureus infections, granulomas of lung, septic embolism, pulmonary edema, and viral infections ● Sudden death is related to overdosing, respiratory depression, decreased cardiac output, and severe pulmonary edema Fentanyl ● Synthetic opioid analgesic, 50-100 times more potent than morphine ● Rising use and overdoses documented Air pollution ● Air pollution is the largest single environmental health risk ● More than 95% of the world's population live in areas of unhealthy air ● Air pollution is the leading environmental cause of death worldwide ● Indoor and outdoor exposure to air pollution contributes to premature deaths ● Solid fuel burning in homes exposes 2.5 billion people to household pollution ● China and India have the highest air pollution health burdens Ambient particulate matter (PM2.5) ● Ambient particulate matter is ranked as the sixth highest risk factor for early death ● Ozone, a form of oxygen in the stratosphere, contributes to deaths from chronic lung disease Heavy metals as environmental pollutants ● Common heavy metals include lead, mercury, arsenic, and cadmium ● Damage from metals involves DNA repair mechanisms, tumor suppressor functions, and signal transduction pathways ● Lead affects multiple organ systems and increases oxidative stress ● Lead exposure disrupts cellular ion status and protein function Effects of lead exposure on children's health ● Damage to the brain, nervous system, and development ● Slowed growth ● Learning and behavior problems ● Hearing and speech problems ● Lower IQ and decreased ability to pay attention ● Underperformance at school Sources of lead exposure in children ● Homes built before 1978 with lead-based paint ● Lead in certain products such as toys and toy jewelry ● Certain jobs and hobbies involving working with lead-based products ● Lead in certain water pipes ● Candies imported from other countries and traditional home remedies Updated recommendations on children's blood lead levels ● Reference level of 5 micrograms per deciliter (mcg/dL) to identify high blood lead levels ● Focus on primary prevention of lead exposure to reduce or eliminate dangerous and toxic sources ● Chelation therapy recommended for children with blood lead test results showing 45 mcg/dL Why children are more susceptible to the effects of lead ● Increased hand-to-mouth behavior ● Immature blood-brain barrier during fetal development ● Greater absorption of lead in infants compared to adults ● Rapid turnover in skeletal bone causing continuous leaching of lead into blood