Transcript File

Faculty of Medicine
Introduction to Community Medicine Course
(31505201)
Unit 3 Public Health/Environmental Health
Water pollution
Food Safety
By
Hatim Jaber
MD MPH JBCM PhD
13-10-2016
1
Introduction to Unit 3
Public Health and Environment
5 lectures
• Introduction to Public Health and Environment-- 9-102016
• Environment 1- Air pollution—11-10-2016
• Environment 2- Water Quality and Food
Safety – 13-10-2016
• Environment 3 -Waste Management --16-10-2016
• Occupational Health 4 – 18-10-2016
2
Presentation outline
Time
Water Quality, Quantity and Health
12:00 to 12:10
Water pollution and Sources of water
and contaminations
Water related diseases
12:10 to 12:20
Food Safety and health
12:30 to 12:40
Food borne Diseases and HACCP
12:40 to 12:50
12:20 to 12:30
3
Water Quality and Health
• The quality of drinking-water is a powerful
environmental determinant of health
• Water is essential for life, but it can and does
transmit disease in countries in all continents –
from the poorest to the wealthiest.
• The most predominant waterborne disease,
diarrhoea, has an estimated annual incidence of
4.6 billion episodes and causes 2.2 million deaths
every year
• Millions of people are exposed to unsafe levels of
chemical contaminants in their drinking-water
How much water does an individual use?
A hierarchy of water requirements
In Jordan
Per capita water supply for all uses is less than
15% in comparison to the international
standards.
General information of water sources
Sources
Quality
Quantity
Good quality for deep
Good with little
Groundwater aquifers; poor to fair
variation
for shallow aquifers
Good with little
variation for
artesian flow
springs; variable
with seasonal
fluctuations likely
for gravity flow
springs.
Accessibility
Reliability
Depends on the
best location of
well; pumping
required unless
artesian well
Good,
maintenance on
pump required
Moderate if need
regularly, must
to pump
not over pump the
aquifer
Storage necessary
for community
water supply;
gravity flow
delivery for easy
community
access.
Good for artesian
flow and gravity
overflow; fair for
Fairly low cost;
gravity
with piped system
depression; little
costs will rise.
maintenance
needed after
installation.
Springs and
Seeps
Good quality;
disinfection
recommended after
installation of spring
protection.
Ponds and
Lakes
Fair to good; need
Fair to good in large
Very accessible
for a good
ponds and lakes; poor
using intakes;
program of
Good available
to fair in smaller
pumping required operation and
quantity; decrease
water bodies;
for delivery
maintenance for
during dry season.
treatment generally
system; storage
pumping and
necessary.
required.
treatment
systems.
Cost
Moderate to high
because of need to
pump and treat
water.
Information of water sources
Sources
Quality
Quantity
Accessibility
Reliability
Cost
Good for mountain
streams; poor for
Streams and
streams in lowland
Rivers
regions; treatment
necessary.
Maintenance
required for both
Moderate: seasonal Generally good;
type systems;
variation likely;
need intake for
much higher for
some rivers and
both gravity flow
pumped system;
streams will dry up and piped
riverside well is a
in dry season.
delivery.
good reliable
source.
Moderate to high
depending on
method;
treatment and
pumping
expensive.
Fair to poor;
Rain
disinfection
Catchments
necessary
Moderate and
variable; supplies
unavailable during
dry season; storage
necessary.
Low-moderate
for roof
catchments; high
for ground
catchments
Good; cisterns
located in yards
of users; fair for
ground
catchments.
Must be rain;
some
maintenance
required.
What’s the Quality of Our Drinking Water?
Drinking water is defined as potable water used for
domestic purposes, food, industries, and ice
manufacturing.
Community asks for
information:
 Sodium






Hardness
Mineral content (TDS)
pH
Chlorine
Coliform Bacteria
Contamination
Standard conditions
1 Microbial Parameters
1.1 The maximum allowable limit for the TCC (MPN/100ml)
should be < 1.1 as a result of the Multiple Tube Test and 0 as result of the Membrane
Filtration Test
.1.2 The sample should be free from
a) Thermo tolerant coli form bacteria, and
b) Enteric viruses and germs
2 Biological Parameters: Drinking water should be free from a) Any
pathogenic protozoa
b) Any pathogenic nematode eggs c) Any free living pathogens,
and d) Fungus
.3 Physical Characteristics The physical characteristics of water should
be as follows:
a) Taste: Acceptable for the majority of people b) Odor: Acceptable
for the majority of people c) Color: The maximum allowable limit is 10 units –15 units
d) Turbidity: The maximum allowable limits is 1 – 5 NTU
.4 Chemical Characteristics
Where chlorine is used to disinfect the drinking water, the maximum allowable limit
for free chlorine supplied to the consumer is 0.2-1mg/l after 15 minutes from
disinfection and 15 minutes before arriving to the consumer.
Parameters Related to Water Taste read as indicated in the following table. Note that
the lower range level is obligatory for private wells.
Primary drinking water standards criteria
• Microorganisms - Giardia
lamblia; Virus;
Legionella;Turbidity
• Disinfection Byproductsbromate, chlorite,
trihomethanes; haloacetic
acids
• Disinfectantschloramines, chlorine and
chlorine dioxides
• Inorganic Chemicals –
Arsenic, barium, fluoride,
copper, lead,
• Organic Chemicals –
Benzine; Carbon
tetrachloride;
Dichloromethane
• Radionuclides – Uranium;
Alpha particles; Beta
particles and photon
emitters
Secondary - Drinking water standards
Contaminant
Aluminum
Chloride
Color
Copper
Corrosivity
Fluoride
Foaming Agents
Iron
Manganese
Odor
pH
Silver
Sulfate
Total Dissolved Solids
Zinc
Secondary Standard
0.05 to 0.2 mg/L
250 mg/L
15 (color units)
1.0 mg/L
noncorrosive
2.0 mg/L
0.5 mg/L
0.3 mg/L
0.05 mg/L
3 threshold odor number
6.5-8.5
0.10 mg/L
250 mg/L
500 mg/L
5 mg/L
Community actions to improve WQ
Source of pollution
Agricultural: from
both agriculture
practices and
livestock rearing.
Storm water:
Generated by
rainfall storms
Sewer
Industrial
What the communities can do
o Managing pastures to maintain vegetative cover and
stable soils
o Employing conservation farming technique
o Minimizing stock access to streams and damage to
stream banks
o Actively controlling erosion problems Constructing
farm dams to encourage water plant growth so that
they act as filters for run-off
o Maintaining and operating on-site household
wastewater systems (septic tanks and aerated
wastewater treatment units) to prevent nutrients
getting into streams or groundwater
o regulating industrial activities, as well as controlling
diffuse sources, to prevent water pollution
o Protecting local wetlands for their role in filtering
sediment and nutrients and providing a diversity of
wildlife habitat
o Reusing effluent where possible
Methods for purification
•
•
•
•
•
•
•
Simplest is boiling
Filtration
Chlorination
Ozone
UV treatment
Water guard (Sodium hypo chlorite)
Distillation
Filters
•
•
•
•
•
•
•
Sand filters for large communities
Gravity filters for small communities
Domestic household filters
Filter cartridges ( for many types of ions)
Activated carbon or charcoal filters
Fluoride filters – CDN as a leader
Reverse osmosis – More advanced
The working principles of some specific filters
1. Ozone filters – Through oxidation process, all organic,
inorganic and biological substances are destroyed
2. Steam distillation – Natural methods which is able to
remove Biological Entities, Heavy Metals, Organic
Chemicals, Inorganic Chemicals & Radioactive Material
3. Carbon filters (Charcoal) – A good media for a wide range
of contaminant like chlorine, pesticides, herbicides and
inorganic materials
4. Far Infrared Light (FIR) - Very suitable for toxin removal
5. Ultraviolet Light – Very cheap to use – Deactivates the
DNA of bacteria, virus and other pathogens
6. The ceramic water filters – Very cheap and
affordable- removes dirt, microbes, virus
and bacteria
7. CDN Fluoride filters- Single and combined
“These two filters are cheap and wananchi
friendly”
Sand filters
UV filters
Ceramic water filters
CDN Single and combined Fluoride filters
Water pollution and Water related
diseases
Pollutants Found in Runoff
Sediment
Soil particles
transported from
their source
Biochemical Oxygen Demand (BOD)
● Oxygen depleting material
Leaves
Organic material
Toxics
● Pesticides
 Herbicides
 Fungicides
 Insecticides
● Metals (naturally occurring
in soil, automotive
emissions/ tires)
 Lead
 Zinc
 Mercury
● Petroleum Hydrocarbons
(automotive exhaust and
fuel/oil)
Debris
Litter and illegal dumping
Nutrients
● Various types of materials that
become
dissolved and
suspended in water (commonly
found in fertilizer and plant material):
 Nitrogen (N)
 Phosphorus (P)
Bacteria/ Pathogens
Originating from:
● Pets
● Waterfowl
● Failing septic systems
Thermal Stress
Heated runoff,
removal of
streamside
vegetation
Major Water Pollutants and Their Sources
Common Diseases Transmitted to Humans
through Contaminated Drinking Water
What Can You Do? Water Pollution,
Ways to Help Reduce Water Pollution
Diseases Related to Water
Water-borne
Diseases
Water-based
Diseases
Water-washed
Diseases
Water-related
Diseases
Water-borne Diseases
Diseases caused by ingestion of water
contaminated by human or animal
excrement, which contain pathogenic
microorganisms
Include cholera, typhoid, amoebic and
bacillary dysentery and other diarrheal
diseases
Diarrheal Diseases
•
•
•
•
•
•
Giardiasis (Protozoan)
Cryptosporidiosis (Bacteria)
Campylobacteriosis (Bacteria)
Shigellosis (Bacteria)
Viral Gastroenteritis (Virus)
Cyclosporiasis (Parasite)
In addition, water-borne disease can
be caused by the pollution of water
with chemicals that have an adverse
effect on health
•
•
•
•
•
•
Arsenic
Flouride
Nitrates from fertilizers
Carcinogenic pesticides (DDT)
Lead (from pipes)
Heavy Metals
Water-washed Diseases
Diseases caused by poor personal hygiene
and skin and eye contact with
contaminated water
These include scabies, trachoma, typhus, and
other flea, lice and tick-borne diseases.
Water-based Diseases
Diseases caused by parasites found in
intermediate organisms living in
contaminated water
Includes
Schistosomiasis
and Dracunculiasis
Water-related Diseases
Water-related diseases are caused by insect
vectors, especially mosquitoes, that breed
or feed near contaminated water.
They are not typically associated with lack of
access to clean drinking water or sanitation
services
Include dengue, filariasis, malaria,
onchocerciasis, trypanosomiasis and
yellow fever
Other Water-borne diseases
• Bathing
• Swimming
• Other recreational activities that have
water contact
• Agriculture
• Aquaculture
The Problem
• ~80% of infectious diseases
• > 5 million people die each year
• > 2 million die from water-related diarrhea
alone
• Most of those dying are small children
• Lost work days
• Missed educational
Other
opportunities
Consequences
• Official and unofficial
healthcare costs
• Draining of family resources
Food Safety and health
Food security and safety
• Food security: availability of the right quality and
quantity of food to supply the recommended
daily nutrients to maintain good health and
prevent malnutrition.
• Food safety: reflection of food sanitation and is
related to safeguarding from the immediate or
late health hazards resulting from biological,
chemical , or physical contamination of food (
production, transport, distribution, processing,
and subsequent use are properly handled )
What is Food Safety?
Food Safety is making a food safe to eat and
free of disease causing agents such as:
• Too many infectious agents
• Toxic chemicals
• Foreign objects
What is Food Quality?
Food Quality is making a food desirable to eat
with regards to good taste, color, and texture;
bad food quality can be judged by:
• Bad color
• Wrong texture
• Smells bad
• Temperature
• Adulteration, contamination of food is major cause
of ill health.
• The GIT is the usually portal of entry for many
infectious and parasitic organisms. Food stuff
readily become contaminated through human,
insects and other intermediaries.
• In addition a number of organism and toxic
chemical can be introduced deliberately or
accidentally at any stage between production and
consumption.
• Control of the cleanliness and composition of food
is clearly important but it is more complex and
difficult than ensuring a safe water supply
Food preservation:
Dehydration ( Drying )
Osmotic inhibition
Heating to kill micro organisms
Oxidation (eg. Use of sulphur dioxide )
Toxic inhibition (eg. smoking ).
Low temperature inactivation (freezing )
Vacuum -packing
What are the Types of Food Hazards?
• Biological: bacteria, viruses, parasites
• Chemical: heavy metals, natural toxins,
sanitizers, pesticides, antibiotics
• Physical: bone, rocks, metal
Biological Hazards in Food
Biological = Living Organisms
• In Meat and Poultry:
• Salmonella bacteria (poultry and eggs)
• Trichinella spiralis parasite (pork)
On Fruits and Vegetables:
• E. coli bacteria (apple juice)
• Cyclospora parasite (raspberries)
• Hepatitis A virus (strawberries)
Common Food borne Bacteria
How can you prevent Biological
Hazard to Foods
Prevention of microbes growing
– Holding at low temperatures (<40oF)
– Cooling from 140o-40oF quickly
Cooking helps to kill microbes
– >165oF(73o C) for poultry and eggs
– >155oF (68o C) for ground beef
– >160oF (71o C) for pork
Chemical Hazards in Food
Chemical hazard: a toxic substance that is produced
naturally added intentionally or un-intentionally
• Naturally-occurring:
– Natural toxins (aflatoxins, marine toxins)
• Added intentionally:
– Antibiotics, preservatives
• Added non-intentionally:
– Cleaning agents, Pesticide Residues
Physical Hazards in Food
Physical hazard: a hard foreign object that can
cause illness or injury
• Inherent to the food or ingredient
– Bone fragment, feathers
• Contaminant during processing
– Stones, rocks, dirt, fingernails
Food borne Diseases
What are the foodborne illness risk
factors





Food from unsafe source
Inadequate cooking
Improper holding temperature
Contaminated equipment
Poor personal hygiene
Microbiological pathogens
Food poisoning
Infective food poisoning
Occurs as a result of eating
food contaminated with
bacteria itself
Examples; Salmonella,
Listeria and Escherichia coli.
Toxic food poisoning
Some bacteria produce toxins
,these toxins cannot be
removed or inactivated by
cooking.
Examples Staphylococcus
aureus, Clostridium perfringens
What is a Foodborne Illness?
Foodborne illnesses are caused by agents that enter the
body through the ingestion of food.
• Every person is at risk of foodborne illness.
• No long-term health threat to average person
• May be serious for very young, very old, people with long
term illness
• Reaction may occur in a few hours or up to several days
after exposure
Symptoms
• Abdominal cramps, headache, vomiting, diarrhea (may be
bloody), fever, death
What is the Impact of Foodborne
Illness?
• The global incidence of foodborne disease is
difficult to estimate
• Upto 30% of the population annually
• 2.1 million people died from diarrheal
diseases (2001)
– Food & Water Contamination
– Malnutrition & Death in Infants & Children
What is the Impact of Foodborne
Illness?
In the US annually:
• 76 million cases of foodborne diseases
– 325,000 hospitalization
– 5,000 deaths
China (1994) Salmonella Outbreak estimated
224,000 persons
Why is Foodborne Illness increasing in
the US?
Food:
– Preference for “rare” meats
– Increase shelf life of products which allow for bacterial
growth
– Centralized food production
– Increase consumption of imported ready-to-eat foods
Host:
– Use of immunity suppressant medications & conditions
(HIV/AIDS)
– Increase in the number of elderly
Hazard Analysis Critical Control Point
Hazard
Analysis
and Critical
Control
Point
(HACCP)
What is Hazard Analysis Critical
Control Point (HACCP)?
The purpose of HACCP is to help ensure the
production of safe food
• The goal of HACCP is to prevent and/or minimize
risks associated with biological, chemical, and
physical hazards to acceptable levels
• It is based on PREVENTION rather than detection of
hazards
• Pioneered in the 1960’s: first used for the space
program (Pillsbury & NASA)
The HACCP
 It is the system that is required for any food
business or organisation in most countries.
 The joint FAO / WHO Codex Alimentarius
Commission recommends the HACCP approach
to enhance Food Safety in all process of food
production.
Route #1:
Inhalation
Inhalation:
Breathing. When
chemicals enter the body
through this route of
exposure, they can get
stuck in the lungs and/or
be taken up into the
bloodstream.
66
What are the Steps involved in
HACCP?
1. Identify hazards
2. Determine Critical
Control Points (CCPs)
3. Determine safety
limits for CCPs
4. Monitor CCPs
5. Corrective action
6. Record data
7. Verify that the system
is working
• 1-Perform hazards analysis
• 2-decide on the critical control
point CCPs
• 3-Determine the critical limits
• 4-Establish procedures to
monitor CCPs
• 5-Establish corrective actions
• 6-Establish verification
procedures
• 7-Establish a record keeping
system
The HACCP Advantages
Gives insight in the critical control points of the
product process
 Gives trust for the consumer that products are
produced safely and hygienically
 Reduces the costs of food borne illness.
The HACCP disadvantages:
 Need to train supervisors, managerial and
production staff
 Reduced Staff time available for other tasks
 Increased production , implementation and
supervisory costs
 Reduced flexibility in production process and
introduction of new products.