Relation between environment and health

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• Relation between environment and health
• Prof. Madi Al Jaghbeer

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• Content
• Definition of health and environment.
• Theories of disease causation.
• Environmental diseases.
• Environmental health.
• Environmental health actions (interventions).

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• Health according to WHO is a state of complete
  physical , mental and social well-being and not
  merely the absence of disease or infirmity .
• Environment everything that surrounds us that
  is affected by us and is affecting us .

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• Theories of diseases causation
• Humoral theory (Hippocrates).
• Contagion theory (Fracastoro).
• Germ theory ( Pasteur , Lister and Koch).
• Current disease concepts .

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• Humoral theory (Hippocrates) 430-330 B.C.
• The Human body contains blood, phlegm , yellow
  bile and black bile . These are the things that
  make up its constitution and causes its pains and
  its health .
• Health is primarily a state in which these
  constituent substances are in the correct
  proportion to each other both in strength and
  quantity and are well mixed .

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• Diseases arise from humoral imbalances and
  imbalances arise from natural causes
• Heredity phlegmatic parents have phlegmatic
  children .
• Regimen Diet and other behavior .
• Climate Temperature , wind and moisture .

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• Treatment either addresses
• The causes of humoral imbalance change in diet
  or environment.
• Humoral imbalance itself rid body of excess
  bile or phlegm (induce vomiting , evacuation of
  bowels and veins were opened to let blood ).

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• Contagion theory (Fracastoro) 1546
• Contagion is a corruption which develops in the
  substance of a combination , passes from one
  thing to another and is originally caused by
  infection of the imperceptible particles .
• He called the particles Seminaria (seeds).
• Differences between diseases are explained by
  theyre having different active particles
  different seeds.

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• He did not abandon the humoral theory he blended
  it with his contagion theory suggesting that
  seeds for different diseases have different
  affinities for different humors .
• Treatment destroy or expel the seeds of
  contagion
• Destroy extreme heat and cold.
• Expel bowel movements , urination , sweating
  and blood-letting .

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• Germ Theory
• Pasteur (1850s) Was able to show that yeast
  increased in weight , nitrogen and carbon content
  during fermentation , inferring that yeast is a
  living organism that is a cause of fermentation
  in beer and wine .
• He challenged the theory of spontaneous
  generation fermentation does not take place in
  absence of contamination by air.

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• Joseph Lister (1867) appreciated the
  significance of Pasteurs theory , and stated
  it is not to its oxygen or to any of its gaseous
  constituents that the air owes this property but
  to minute particles suspended in it which are the
  germs of various low forms of life .
• Robert Koch (1870-1880) there are many
  different kinds of bacteria and specific kinds
  are responsible for specific disease .

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• Current disease concepts
• 1890 researchers has recognized that microbes
  much smaller than bacteria are responsible for
  rabies and many other diseases , modern concept
  of virus originated.
• 1930s antibiotic cures for bacterial infections
  .

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• Researchers in 20th century have revealed other
  causes of disease (other than infectious)
• Genetic 2) nutritional 3) immunological
• 4) metabolic 5) cytological .
• Modern medicine classifies diseases according to
• Organ systems cardiovascular , renal ,
  respiratory etc
• Pathogenesis oncology , infectious , metabolic
  , nutritional etc

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• Environmental diseases
• Lesions and diseases caused by exposure to
  chemical or physical agents in the ambient ,
  workplace , and personal environment .
• Personal environment environment that pertains
  more to the individual and is greatly influenced
  by use of tobacco , alcohol ingestion ,
  therapeutic and non-therapeutic drug consumption
  and the likes.

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• Factors in the personal environment generally
  have a larger effect on human health than does
  the ambient environment .
• Environmental diseases could be encountered due
  to
• Disasters (Chernobyl nuclear accident ).
• Chronic exposure to relatively low levels of
  contaminants .

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• Sensitivity of individual towards contaminants is
  affected by various factors
• Age .
• 2)Genetic predisposition.
• 3) different tissue sensitivities of exposed
  persons.

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• Important environmental diseases
• Lung diseases
• Asthma plant pollen , dust , mold and animal
  dander.
• Black lung disease coal miners lungs become
  coated with coal dust causes chronic condition in
  which breathing becomes painful and difficult.

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• 3) Bronchitis Fire-fighters and smokers are at
  increased risk .
• 4) Asbestosis breathing asbestos causes severe
  lung disorder could lead to lung cancer ,
  asbestos was used for insulation in houses ,
  schools and work-places before laws were passed
  to ban its use .
• 5) Silicosis Lung disease caused by exposure to
  the silica in the dust of clay . Pottery workers
  are at increased risk .

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• Cancers
• beside lung cancer , environmental toxins that
  could lead to cancers pesticides , herbicides ,
  radioactive substances.
• Liver or bladder cancer in people working in
  plastic manufacturing.
• Lung cancer asbestos , chromium and coal tar.

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• Gulf war syndrome
• many US veterans have complained about symptoms
  that they attribute to their participation in the
  Persian Gulf war in 1991.
• Symptoms chronic fatigue , aching muscles and
  joints , skin rashes , memory loss , miscarriages
  and babies born with birth defects.
• Scientists do not know main cause but argue that
  veterans might be reacting to chemical weapons ,
  biological weapons , pesticides , vaccines , oil
  fires or infectious diseases that they were
  exposed to .

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• Sick building syndrome
• People attribute a variety of symptoms to the
  building were they work .
• Common complaints headaches , dizziness ,
  nausea , tiredness , concentration problems ,
  sensitivity to odors , dry itchy skin , dry cough
  , irritated eyes , nose and throat .

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• generally as soon as affected people leave the
  building their symptoms vanish and they feel well
  again .
• Factors that may contribute
• Humidity
• poor ventilation
• poor temperature control
• pollution from outdoor sources (pollen , car
  exhaust or smoke )
• chemicals from inside the building ( cleaning
  agents , glues , copy machine chemicals )
• Bacteria ,viruses and molds .

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• Birth defects infertility , miscarriages ,
  still birth , childhood cancer and birth defects
  may have links to environmental toxins (pregnant
  woman exposed to lead her child has high risk of
  being born with behavior and nervous system
  problems).
• Chemical poisoning lead , mercury and cadmium.

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• Environmental health
• According to World Health Organization is the
  control of all factors in the environment which
  exercise a harmful effect on mans physical
  development , health and survival .
• The WHOs definition is not all-inclusive in
  terms of the natural environment , and includes
  only those aspects that are modifiable (not
  necessarily immediately but with solutions that
  are already available ) .

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• Examples of included environmental factors
• 1) pollution of air , water , or soil with
  chemical or biological agents
• 2) UV and ionizing radiation ( although natural
  UV radiation from space is not modifiable or only
  in a limited way such as by reducing substances
  that destroy the ozone layer ) , individual
  behavior to protect oneself against UV radiation
  is modifiable .
• 3) noise , electromagnetic field .
• 4) occupational risks.
• 5) built environments including housing , land
  use patterns and roads.
• 6) agricultural methods , irrigation schemes.
• 7) man-made climate change , ecosystem change.
• 8) behavior related to the availability of safe
  water and sanitation facilities such as washing
  hands and contaminating food with unsafe water or
  unclean hands

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• Examples of excluded environmental factors
• 1) alcohol and tobacco consumption and drug
  abuse.
• 2) diet (although it could be argued that food
  availability influences diet ).
• 3) the natural environments of vectors that
  cannot reasonably modified (e.g. in rivers , in
  lakes , in wetlands) .
• 4) unemployment (provided that it is not related
  to environmental degradation , occupational
  disease, etc).
• 5) natural biologic agents such as pollen in the
  outdoor environment.
• 6) person to-person transmission that cannot
  reasonably be prevented through environmental
  interventions such as improving housing ,
  introducing sanitary hygiene or making
  improvements in the occupational environment.

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• Environmental health actions (interventions)
• First action (Sir Edwin Chadwick ) .
• Current actions (WHO) .

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• First environmental health action
• Environmental health has its origins in the early
  1800s. The first public health act was
  introduced in 1842 as the result of a report made
  to parliament by Sir Edwin Chadwick on the
  sanitary conditions of the laboring population of
  Great Britain . The report told the story of
  disease caused , aggravated and spread by damp
  and atmospheric impurities produced by
  decomposing waste and overcrowding

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• In his report Sir Chadwick stated that the
  annual loss from filth and bad ventilation are
  greater than the loss from death or wounds in any
  wars in which the country has been engaged in
  modern times . He also stated the younger
  population bred up under noxious physical
  agencies is inferior in physical organization and
  general health to a population preserved from the
  presence of such agencies .

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• Current environmental health actions
• Environmental burden of disease (EBD).
• Country profiles of EBD .
• Health impact assessment .

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• Environmental Burden of disease
• quantifies the amount of disease caused by
  environmental risks .
• through death incidence or DALY .
• DALY (disability adjusted life years ) time
  based measure that combines years of life lost
  due to premature mortality and years of life lost
  due to time lived in states of less than full
  health .

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• WHO report (2006 ) states that approximately one
  quarter of the global disease burden and more
  than one third of the burden among children is
  due to modifiable environmental factors.
• Environmentally mediated disease burden is much
  higher in the developing countries (communicable
  diseases) although in cases of certain
  non-communicable diseases ( CVD and cancers ) it
  is larger in developed countries.

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• Children bear the highest death toll with more
  than 4 million environmentally caused death per
  year especially in developing countries.
• Diseases with high EBD
• Diarrhea 94 of the diarrheal burden of disease
  is attributable to environment and is associated
  with risk factors such as unsafe-drinking water
  and poor sanitation and hygiene
• Lower respiratory tract infections 20 in
  developed countries and 42 in developing.

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• 3) Other unintentional injuries from workplace
  hazards , radiation and industrial accidents 44
• 4) Malaria 42 .
• Total number of lives lost each year as result of
  environmental factors was 15 times higher in
  developing countries than developed countries.

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• Means of reducing EBD
• Promotion of safe household water storage.
• better hygiene measures.
• use of safer and cleaner fuels.
• more judicious use and management of toxic
  substances in home and work place .
• poverty reduction , well-being and economic
  development.
• Cooperation between health sectors and other
  sectors such as energy , transport , agriculture
  and industry .

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• Country profile of environmental burden of
  disease
• Updated country data on the burden of disease
  that is preventable through healthier
  environments.
• it provides an overview of summary information on
  selected parameters that describe the
  environmental health situation of a country as
  well as preliminary estimates of health impacts
  caused by environmental risks .

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• These country estimates are a milestone in a
  first step to assist national decision makers in
  the sectors of health and environment to set
  priorities for preventive actions .
• 1st step quantifying the burden.
• 2nd step for countries to select appropriate
  interventions .

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• Health impact assessment (HIA)
• According to WHO is a combination of procedures ,
  methods and tools by which policy or project may
  be judged as to its potential effects on health
  of the population and the distribution of those
  effects within the population .

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• Value of HIA
• Better informed decision-makers and decisions.
• healthier land uses and community designs .
• increased awareness and understanding of health
  consequences .
• Challenges of HIA
• Lack of time
• Lack of resources (human and money ) .

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Thank you very much
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• References
• 1)World health organization environmental
  health topics .
• 2)The concept of disease structure and change
  Paul Thagard University of Waterloo-Ontario
  Philosophy department (1997)
• 3) Robbins basic pathology Kumar , Abbas,
  Fausto and Mitchell 8th edition chapter 8
  (2007)
• 4) Environmental diseases U.S. National Center
  for Environmental Health (NCEH), Centers for
  Disease Control and Prevention (CDC)

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• 5) WHO Quantification of the disease burden
  attributable to environmental risk factors
  (2006).
• 6) Chadwicks report on Sanitary conditions
  Laura Del Col West Virginia University (2002)
• 7) Health impact Assessment Quick guide
  National Association of County and city health
  officials (2008) .