Chapter 28

1. Chapter 28 Environmental Hazards and Associated Problems

2. Introduction • Agents in the environment can cause damage to cells and organs of the human body at the time of exposure or after repeated exposures. • Safe levels of agents must be calculated based on total life exposure.

3. Introduction (Cont.) • Often, damage becomes apparent as aging reduces the physiological reserves of tissues. • Increase in childhood cancers and hypersensitivities • Hypersensitivities to new chemical substances have increased. • Chemicals in food processing • Synthetic materials in buildings and furnishings • Cosmetics and toiletries • Microbes in water and food supply

4. Safety Procedures • OSHA: Occupational Safety and Health Administration (in the United States) and similar international agencies establish protocols for: • Safety procedures in workplace • Safety procedures in the environment • Infection control • Protective equipment • Exposure to harmful substances and hazardous material

5. Chemicals • Tissue damage can result from a large chemical dose in a single incident or from repeated exposure to small amounts. • Unwanted chemicals • Ingested in contaminated food, water, toys, household objects • Inhaled • Absorbed through the skin

6. Examples of Chemicals • Hexachlorophene • Was once widely used in hospitals as an aseptic in soaps and powders • Absorbed through the skin (eventually leads to brain damage) • Use now restricted • Exposure to plastics • Phthalates used to soften plastics and prevent shattering • Toys, bottle nipples, and others—withdrawn from U.S. and Canadian markets • Acids and bases

7. Chemicals: Heavy Metals • Lead and mercury • Can accumulate in tissues with long-term exposure • Lead • Can be ingested in food or water • Inhaled • Found in lead pipes and batteries • Lead-based paint (toys, furniture) • Common childhood poison

8. Toxic Effects of Lead • Hemolytic anemia • Inflammation and ulceration of the digestive tract • Inflammation of the kidney tubules • Damage to the nervous system • Neuritis • Encephalopathy • Seizures or convulsions • Delayed development and intellectual impairment • Irreversible brain damage

9. Lead Poisoning of Red Blood Cells

10. Chemicals: Inhalants • Particulates • Asbestos • Silica • Pesticides • Illness depends on type of pesticide, amount and duration of exposure • Gases • Sulfur dioxide • Ozone • Solvents • Benzene • Acetone

11. Sources of Toxic Inhalants • Factories, laboratories, mines, artists’ workshops • Insecticides, aerosols • Paints, glues • Furniture, floor coverings • Poorly maintained heating systems • Smog • Hydrogen sulfide • Particles from dust and smoke • Carbon monoxide

12. Examples of Toxic Inhalants • Asbestos, iron oxide, silica • Inhaled particles • Lung damage in mine workers and other industries (Note: Family members may also be exposed when clothing transfers toxins in the home environment.) • Asbestos: fibrosis of the lungs • Cigarette smoking • Lung disease, including cancer • Bladder cancer • Cardiovascular disease • Predisposition to numerous other diseases

13. Lung with Asbestos Bodies

14. Physical Agents: Hyperthermia • Excessive elevation of body temperature • Syndromes include: • Heat cramps with skeletal muscle spasms • Caused by loss of electrolytes • Heat exhaustion • Sweating, headache, nausea, dizziness, fainting • Heat stroke • Shock • Coma • Very high core body temperature

15. Physical Agents: Hypothermia • Exposure to cold temperatures • Localized frostbite • Fingers, toes, ears, exposed part of face • Systemic exposure • Caused by submersion in cold water, lack of adequate clothing, wet clothing • Core body temperature drops; capillaries and cell membranes are damaged. • Abnormal shift of fluid and sodium • Hypovolemic shock and cell necrosis

16. Physical Agents: Radiation • Ionizing radiation • Includes x-rays, gamma rays, protons, neutrons • Rays differ in energy levels and ability to penetrate body tissue, clothing, or lead • Amount of radiation absorbed by the body is measured in rads (radiation-absorbed dose) • Natural sources • Sun and radioactive materials in soil • Other sources • Radon gas (homes), industry, nuclear reactors, diagnostic procedures

17. Physical Agents: Radiation (Cont.) • Damage may occur with a single large exposure. • May accumulate with repeated small exposures • Not been well studied • Exposure to large doses • Leads to radiation sickness • Cumulative damage • Skin cancers (sun exposure) • Radiation primarily affects actively dividing cells. • Epithelial tissue, bone marrow, gonads

18. Physical Agents: Noise • Single loud noise • Example: gunshot • May rupture the tympanic membrane or damage nerve cells in the inner ear • Noise in the workplace • Cumulative damage • Ear protection is now required in most noisy work environments. • Home or social environment may exceed safe levels for noise.

19. Biological Agents: Food and Water Poisoning • Contaminated food and water • May be the result of heat-labile toxins produced in contaminated food • Botulism poisoning • May be the result of heat-stable toxins produced in contaminated food • Staphylococcal contamination • May be the result of infection with microbe • Most common outbreaks are caused by strains of Escherichia coli or Salmonella.

20. Biological Agents: Bites and Stings • Direct injection of animal toxin into the body • Neurotoxins by spiders or snakes • Vascular agents in jellyfish • Transmission of infectious agents through animal or insect vectors • Rabies • Malaria • Lyme disease • Allergic reaction to insect proteins • Bee or wasp stings