Transcript Download: Iodine initiative - PowerPoint #45381

Iodine and health:
Learning from Tanzania
Promoting Excellence in Science Teaching and Learning
Objectives
 Recognise the symptoms of iodine
deficiency
 Apply knowledge about elements
and compounds
 Evaluate evidence to decide
whether UK salt should be iodised.
2
Swallowing 2 g
of this element
could kill you…
… but compounds including the
element are vital to health.
3
Iodine deficiency causes
goitre and brain damage…
…and may reduce IQ.
enough
iodine
not
enough
iodine
Up to 70% of British young
people do not take in
enough iodine.
Do you?
4
Use the data to estimate the amount
of iodine you consume each day.
Food
Typical
portion
size
Average
mass of
iodine per
portion
(µg)*
200
cm3
150
cm3
1
egg
65
75
20
50 g
100
g
100
g
100
g
25 g
20
115
50
10
5
1
slice 50 g
5
8
100
g
4
Health experts recommend 150 µg / day
 This is the mass of iodine that is in the food as part of a compound.
Iodine is not present as an element on its own.
5
Should the UK add iodine compounds to salt?
6
In the 1980s many Tanzanians
suffered from iodine deficiency
diseases.
So Tanzania introduced a new rule:
iodine compounds must be added to salt.
Did salt iodisation make a difference?
7
Student sheets
Iodine and health: learning from Tanzania
Sheet no.
Title
Notes
SS1
Scientists in Tanzania…
Reusable, one per pair.
SS2
Role play cards
Reusable, one per group of 6.
Cut into cards.
SS3
Role play preparation
Optional, if role play preparation is set
for homework.
Consumable, one per student.
SS4
8
Salt mystery
Reusable, one per pair.
Scientists in Tanzania wanted to find out
whether salt iodisation made a difference… What
did they do?
Salt test – how much salt has
added iodine?
Disease test – how many children
have goitre?
Method
More than 130 000 students brought
salt samples from home into school.
Scientists measured whether each
sample had an iodine concentration
above or below 15 mg/kg of salt.
Method
Health workers
examined more than
140 000 students
for neck swellings.
Results
IN 2009, 84% of salt tested had over
the required 15 mg/kg of iodine.
Results
There is no data for the
1980s, but it is known that
few salt makers added
iodine to salt then.
Urine test – how many children have enough iodine?
Method
More than 4500 students gave urine samples.
Scientists used a special instrument to measure
the iodine concentration in each sample.
Results (for 2009)
Urinary iodine
concentration (µg/litre)
9
Percentage
of students
Below 100 (too low)
25
100 – 300
40
Above 300 (too high)
35
Year
Percentage of students with goitre
1980s
61
2004
12
What to do
Did salt iodisation make a difference?
Study the methods and results of the three
tests.
Did salt iodisation improve health?
Write a paragraph to explain your decision.
Write down any questions you would
like to ask the Tanzanian
scientists about
their work.
STUDENT SHEET 1
Role play cards
Role 1 – health minister
Role 2 – UK dietician
Role 3 – Tanzanian scientist
I am here to listen, learn and
chair the discussion.
I am here to give advice on health,
nutrition and diet.
I am here to tell the UK health minister
about the impact of salt iodisation in
Tanzania.
In the end
I must make
a decision
– should we
make salt
iodisation
compulsory
in the UK?
I do not know whether salt iodisation is
necessary in the UK, since our diets are
very different.
This is what my 14 year old son
eats on a normal school day:
Breakfast – maize porridge
Lunch – rice and kidney beans
Tea – a dish made from
cooked green bananas and
kidney beans, with spinach.
Role 4 – Chinese scientist
Role 5 – UK marketing agency
Role 6 – UK food supplement
I am here to tell the health minister
about my research.
I am here to explain how we can
persuade individuals to make sure
they have enough iodine.
manufacturer
I want to tell the health minister that
salt iodisation is unnecessary.
It is up to individuals to take
responsibility for getting enough
iodine, not the government.
We make iodine tablets that people
can take if they are worried about
not getting enough iodine.
We have successfully persuaded
people to decide to give up
smoking, so we can also
persuade
people to
have enough
iodine.
Iodising salt might encourage people
to eat more salt, causing heart
problems.
I studied the effects of iodine on
the development of over 12 000
children in China.
Children whose mothers did not
have enough iodine during
pregnancy
had lower
intelligence
scores.
10
 A balanced diet can
provide enough iodine.
 Iodine-rich foods include fish and dairy
products. Milk is rich in iodine because
farmers supplement cows’ food with
iodine compounds.
 Salt iodisation might encourage
people to eat more salt. Too much salt
can cause high blood pressure and
heart problems.
 Iodine supplements could be harmful,
because too much iodine causes
health problems.
STUDENT SHEET 2
Role play preparation
In the role play you
will play the part of
an expert in the salt
iodisation debate.
Use the web links below
to research the issue and
gather information to
support your argument.
Write any key facts or statistics in the box below.
My role
Key facts and statistics that support my argument:
Web links
Q and A on iodine deficiency
http://www.bbc.co.uk/news/health22623679
Advice on iodine consumption
http://www.nhs.uk/Conditions/vitaminsminerals/Pages/Iodine.aspx
More detailed information:
The impact of iodine deficiency during
pregnancy on a child’s IQ
http://www.nhs.uk/news/2013/05May/Pages
/Lack-of-maternal-iodine-may-damagechilds-IQ.aspx
Detailed background information about
iodine from the USA National Institutes of
Health
http://ods.od.nih.gov/factsheets/IodineHealthProfessional/#h2
11
STUDENT SHEET 3
Salt mystery
What to do
solution
Observations on adding
silver nitrate solution
Potassium iodide
Sodium chloride
Sodium iodide
1 Place one half spatula measure of potassium
iodide in a test tube. Half fill the test tube with
distilled water.
2 Using a glass rod, stir to dissolve the solid.
3 Add a few drops of silver nitrate solution.
4 Record your observations in a copy of the
table on the right.
5 Repeat steps 1 to 4 for sodium chloride and
sodium iodide.
6 Write a conclusion so far. How do you know
if a compound is an iodide?
7 Now repeat steps 1 to 4 for salt samples X, Y
and Z. Only one has been iodized – but which
one?
8 Write a second conclusion. Which sample
included an iodide compound?
12
X
Y
Z
How Tanzanian salt
makers add iodine
to salt
We spray salt (sodium chloride,
NaCl) with a solution of one
of these compounds:
 sodium iodide (NaI)
 sodium iodate (NaIO3)
 potassium iodide (KI)
 Potassium iodate
(KIO3)
We use about 60 cm3 of solution per tonne of salt.
So the salt we sell is not pure salt – it is a mixture of
two compounds (sodium chloride and a compound
that includes iodine.)
STUDENT SHEET 4
Acknowledgements
This activity was produced by
the Association for Science Education in partnership with
Practical Action as part of the Global Learning Programme.
Promoting Excellence in Science Teaching and Learning
The GLP is a ground-breaking new
programme which will create a national
network of like-minded schools,
committed to equipping their students
to succeed in a globalised world by
helping them to deliver effective
teaching and learning about
international development and
global issues at Key Stages 2 and 3.
13
ASE is providing the science education
support for the Global Learning
Programme which is funded by
the Department for International
Development. This activity can be found
on the Global Learning Programme
www.glp-e.org.uk, ASE Primary upd8
primaryupd8.org.uk and Practical Action
practicalaction.org.uk/schools websites.