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Environmental Health Notes

Introduction to Environmental Health

  • Lecture focuses on Toxic Metals & Elements and their significant impact on human health and ecosystems. Environmental health studies the interrelationships between humans and their environment to promote well-being and foster healthy communities.

Learning Objectives

  • Define heavy metals and toxic elements, understanding their unique physicochemical properties and broad health impacts.

  • Identify diverse exposure pathways (occupational, environmental, dietary) for heavy metals.

  • Recognize complex symptoms of heavy metal exposure, differentiating acute from chronic effects.

  • Discuss differential risks for vulnerable populations (children, fetuses, elderly) due to physiological differences.

Overview of Toxic Metals & Elements

  • Toxic metals are naturally occurring metallic elements, often with high density, that are harmful in high doses. They are persistent and bioaccumulate. Key metals include: Lead, Beryllium, Chromium (Part I) and Arsenic, Cadmium, Fluorine, Mercury, Nickel (Part II).

Exposure Sources

  • Widely distributed in air (industrial emissions), soil (natural deposits, run-off), water (contaminated groundwater, old plumbing), and food (uptake in plants, seafood).

  • Common in workplaces like mining, smelting, welding, battery manufacturing.

  • Ingestion in everyday settings, especially for children (lead from paint/dust).

  • High-risk jobs: workers in mining, battery recycling, heavy manufacturing, and construction.

Symptoms of Exposure

  • Acute Poisoning: Rapid onset of severe symptoms like vomiting, abdominal pain, headaches, dizziness, muscle weakness, confusion, convulsions, coma, or death.

  • Long-term/Chronic Effects: Progressive damage from prolonged lower-dose exposure, including reduced cognitive functioning (IQ, memory), learning impairments, behavioral issues, kidney/liver damage, nervous system disorders, cardiovascular problems, and increased cancer risk.

  • Vulnerability: Children are highly vulnerable due to developing organ systems, maturing metabolic pathways, efficient absorption, and hand-to-mouth behaviors.

Specific Metals and Their Health Impacts

  • Lead (Pb): Cumulative toxicant stored in bone, harmful to children and fetuses (crosses placental/blood-brain barriers). Causes neurodevelopmental delays, reduced IQ, behavioral problems, anemia, kidney damage, reproductive issues, and cardiovascular effects.

  • Beryllium (Be): Primarily an occupational hazard via inhalation. Leads to respiratory issues, including Chronic Beryllium Disease (CBD) – a progressive chronic lung disease.

  • Chromium (Cr): Forms include essential Chromium(III) (Cr(III)) and highly toxic, carcinogenic Chromium(VI) (Cr(VI)). Cr(VI) exposure (inhalation, ingestion, dermal) causes severe digestive and respiratory problems (lung cancer, asthma), and skin issues.

Regulatory Frameworks

  • The Agency for Toxic Substances and Disease Registry (ATSDR) assesses health effects of hazardous substances, guiding research and public health actions.

  • The National Priorities List (NPL) identifies hazardous waste sites eligible for federal Superfund remedial action.

Erin Brockovich's Advocacy

  • Focused on hexavalent chromium contamination in Hinkley, California groundwater. Highlighted environmental pollution's health impacts, leading to a landmark class-action lawsuit against PG&E and raising public awareness on corporate environmental negligence and environmental justice.