Environmental Hygiene

cocept of hygiene

1. Environmental Hygiene: Introduction

2. Plan of the lecture Concepts and etymology of Hygiene Hygiene as a science. Its place among medical sciences. Classification Main objectives of Hygiene Terms and Definitions: Environment, Health, Safety, Disease, and Risk Environmental Factors Importance of the Environmental Health studies Routes of Exposure of Environmental Factors Prevention Sanitary

3. Etymology of Hygiene Hygieia is the Ancient Greek goddess of health, the daughter of the god of healing Asclepius Hygieinos means healthy

4. Hygiene an area of medicine for studying the effect of living and working conditions on human health and developing measures (sanitary norms, rules, etc.) to prevent their adverse effects, to ensure optimum living conditions and to promote health and prolong life

5. Medical Sciences ( hygienistics ), which study the influence of environmental factors on human health, its performance and life expectancy, develop the standards, requirements and sanitary measures aimed at improving the settlements, living conditions and human activities - Environmental Health

6. Environmental Health Science The study of those factors in the environment that affect human health Factors (“pollutants” or “toxicants”) in air, water, soil, or food Transferred to humans by inhalation, ingestion, or absorption Production of adverse health effects

7. WHO Definition of Environmental Health Environmental Health comprises those aspects of human health, including quality of life, that are determined by physical, biological, social, and psychosocial factors in the environment. It also refers to the theory and practice of assessing, correcting, controlling, and preventing those factors in the environment that can potentially affect adversely the health of present and future generations

8. Two main objects of the Hygiene (Environmental Health)

9. Definitions : Environment The circumstances, objects, or conditions by which one is surrounded or The complex of climatic, edaphic (soil-based), and biotic factors that act upon an organism or an ecologic community

10. Public Health Definition of “ The Environment ” All that which is external to the individual host. [It] can be divided into physical, biological, social, and cultural factors, any or all of which can influence health status in populations. −Last, J. M. (Ed.). (1995). A Dictionary of Epidemiology (3rd ed.). New York: Oxford University Press.

11. Definitions : Health The condition of being sound in body, mind, or spirit A flourishing condition or well-being—not just the absence of disease or A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity WHO, 1948

12. Definitions: Disease Trouble or a condition of the living animal or plant body or one of its parts that impairs the performance of a vital function

13. Definitions: Safe Free from harm or risk Secure from threat of danger, harm, or loss Zero risk

14. Definitions: Risk Possibility of loss or injury, peril The chance of loss; the degree of probability of such loss

15. Environmental factors

16. Physical factors

17. Chemical factors

18. Biological factors

19. Factors of human activity

20. Social factors

21. Do you think that Environmental Health issues are among the top three Public Health issues in the country?

22. Contribution of Environmental Factors to Morbidity Globally , an estimated 24% of the disease burden ( healthy life years lost ) and an estimated 23% of all deaths ( premature mortality ) was attributable to environmental factors Among children 0–14 years of age , the proportion of deaths attributed to the environment was as high as 36%

23. The Lancet Commission (2017) Diseases caused by pollution were responsible for an estimated 9 million premature deaths in 2015—16% of all deaths worldwide — three times more deaths than from AIDS, tuberculosis, and malaria combined and 15 times more than from all wars and other forms of violence. In the most severely affected countries, pollution-related disease is responsible for more than one death in four

24. Should You Care about Environmental Health Safety? Acute environmental catastrophes (high-level exposures) Chronic (low-level) exposures Indirect effects of global environmental changes

25. The Wake-up Calls: Environmental Catastrophes Minamata disease (1953–1971) Methyl mercury poisoning (Japan, Iraq and other countries) Seveso, Italy (1976) Leak of toxic gas (TCDD) Bhopal (1984) 16.5 tons of toxic pesticide released, 18 thousand people died, more than 350000 people suffered Chernobyl (1986) Nuclear reactor accident Milwaukee incident (1993) Cryptosporidium in drinking water, 1.6 million people infected

26. Major Air Pollution Episodes Date Place Xs Deaths Dec. 1882 London, England 1,000 Dec. 1930 Neuse Valley, Belgium 63 Oct. 1948 Donora, Penn. USA 20 Dec. 1952 London, England 4,000 Dec. 1962 Osaka, Japan 60 Jan. 1963 New York City 200-405 Nov. 1983 New York City 250 Excess deaths refers to the additional number of fatalities counted above the number expected under otherwise normal conditions

27. The London “Killer” Smog of 1952 Source: Adapted from Turco, R. P.

28. Chemicals in the Environment Roughly 70,000 different synthetic chemicals are on the global market; many others are emitted as by-products of their production, use, or disposal Production of synthetic organic chemicals (e.g., dyes, plastics, solvents) has increased from less than 0.15 billion kilograms (1935) to more than 150 billion kilograms (1995)

29. Why Don’t We Know More about These Chemicals? Number of chemicals (1984—NRC/NAS) Pesticides 3,350 Drugs 1,815 Cosmetics 3,410 Food additives 8,627 Chemicals in commerce (1984) >1 million lbs/ yr 12,860 <1 million lbs/ yr 13,911 Production unknown 21,752

30. Why Don’t We Know More about These Chemicals? Each year ~1,000 new chemicals come on line It costs ~ $ 2 million to do a cancer toxicology screen on each chemical (NTP guidelines) The cancer toxicology screen takes ~2 years

31. Routes of Exposure through gaseous, liquid, & solid media Air Water Food Soil GI Tract GI Tract Skin Skin GI Tract Lungs Adapted from Moeller, D.W.

32. Pollutant Source Pathways Pollutant Source Inhalation Fish Concentration Breast Milk Human Receptor Plant Concentration Soil Concentration Water Concentration Air Concentration Cattle&Poultry Concentration Soil Runoff Root Uptake Water Consumption Soil Ingestion Soil Ingestion Plant Consumption Plant Consumption Fish Consumption Dermal Consumption Egg & Poultry Consumption Dairy & Beef Consumption Adapted from M.J. Derelanko

33. Environmental Pathways for Selected Toxic Agents Agent Disease Source Pathway L. pneumophila Legionnaire’s disease Soil, cooling towers Air, building ventilation systems Salmonella Acute diarrhea Human or animal feces Water, meat, eggs Dioxin Chloracne , soft tissue tumors Herbicides, paper mills, incinerators Air, water, food Pesticides Nervous system tox . Agriculture Food, water Asbestos Asbestosis, lung cancer Insulation, auto brakes Air, water

34. Agents and Vectors Agents Chemical, biological, and physical Vectors Water, air, soil, and food Routes of entry Inhalation, ingestion, absorption

35. The Toxicological Paradigm Exposure Altered structure & function Internal dose Biologically effective dose Early biological effects Clinical diseases Susceptibility Genetic factors Effect modifiers Diet Habits Health Medication Co-exposure

36. The Toxicological Paradigm Exposure Altered structure & function Internal dose Biologically effective dose Early biological effects Clinical diseases Susceptibility Genetic factors Effect modifiers Diet Habits Health Medication Co-exposure

37. Severity of Adverse Health Effects Population exposed

38. Health Effects Adverse vs. beneficial Acute vs. delayed onset Clinical vs. subclinical manifestations Transient (reversible) vs. chronic (irreversible)

39. Examples of Manifestations Lung disease Reproductive effects Teratogenic effects Neurologic effects Immunosuppression and hypersensitivity Cancer

40. Environment Pulls the Trigger Human Health/Disease Intrinsic Genetic Environmental Exposure Age/Time “Genetic loads the gun, but environment pulls the trigger.” -Judith Stern UC Davis

41. Definition of Prevention “Actions aimed at eradicating, eliminating, or minimizing the impact of disease and disability. The concept of prevention is best defined in the context of levels, traditionally called primary, secondary, and tertiary prevention” A Dictionary of Epidemiology, Fourth Edition. Edited by John M. Last

42. Prevention

43. Primary prevention Primary prevention can be defined as the action taken prior to the onset of disease, which removes the possibility that the disease will ever occur It signifies intervention in the pre-pathogenesis phase of a disease or health problem Primary prevention may be accomplished by measures of “Health promotion” and “specific protection”

44. Approaches for Primary Prevention The WHO has recommended the following approaches for the primary prevention of chronic diseases where the risk factors are established: Population (mass) strategy High‐risk strategy

45. Population (mass) strategy “Population strategy" is directed at the whole population irrespective of individual risk levels.   For example, studies have shown that even a small reduction in the average blood pressure or serum cholesterol of a population would produce a large reduction in the incidence of cardiovascular disease   The population approach is directed towards socio‐economic, behavioral and lifestyle changes

46. High‐risk strategy The high‐risk strategy aims to bring preventive care to individuals at special risk   This requires detection of individuals at high risk by the optimum use of clinical methods

47. Prevention Paradox ” A preventive measure which brings much benefit to the population often offers little to each participating individual” Rose, 1985

48. Secondary prevention It is defined as “action which halts the progress of a disease at its incipient stage and prevents complications”   The specific interventions are: early diagnosis (e.g. screening tests, and case finding programs) and adequate treatment

49. Secondary prevention (cont.) Secondary prevention attempts to arrest the disease process, restore health by seeking out unrecognized disease and treating it before irreversible pathological changes take place, and reverse communicability of infectious diseases   It thus protects others from in the community from acquiring the infection and thus provide at once secondary prevention for the infected ones and primary prevention for their potential contacts

50. Early diagnosis and treatment WHO Expert Committee in 1973 defined early detection of health disorders as “ the detection of disturbances of homoeostatic and compensatory mechanism while biochemical, morphological and functional changes are still reversible.”   The earlier the disease is diagnosed, and treated the better it is for prognosis of the case and for the prevention of the occurrence of other secondary cases

51. Tertiary prevention It is used when the disease process has advanced beyond its early stages It is defined as “all the measures available to reduce or limit impairments and disabilities, and to promote the patients’ adjustment to irremediable conditions.” Intervention that should be accomplished in the stage of tertiary prevention are disability limitation, and rehabilitation

52. Disability limitation

53. Impairment Impairment is “any loss or abnormality of psychological, physiological or anatomical structure or function”

54. Disability Disability is “any restriction or lack of ability to perform an activity in the manner or within the range considered normal for the human being.”

55. Handicap Handicap is termed as “a disadvantage for a given individual, resulting from an impairment or disability, that limits or prevents the fulfillment of a role in the community that is normal (depending on age, sex, and social and cultural factors) for that individual”

56. Rehabilitation Rehabilitation is “ the combined and coordinated use of medical, social, educational, and vocational measures for training and retraining the individual to the highest possible level of functional ability.”

57. Concept of control The term “disease control” describes ongoing operations aimed at reducing: The incidence of disease The duration of disease and consequently the risk of transmission The effects of disease, including both the physical and psychosocial complications The financial burden to the community

58. Sanitary Practical implementation of hygienic measures In simple words: Making our environment healthier and safer