Why do large predatory fish carry the most methylmercury?

Methylmercury biomagnifies, increasing in concentration at each step up the food chain. Long-lived predators such as shark, swordfish and marlin accumulate the highest levels.

What are the health effects of methylmercury?

Methylmercury is a neurotoxin that damages the brain and nervous system. The developing brain of an unborn baby is most sensitive.

What does UK advice say about eating shark, swordfish and marlin?

Pregnant women, women trying to conceive and children should avoid shark, swordfish and marlin. Other adults should eat no more than one portion a week.

What limit on tuna is advised during pregnancy, and why?

Pregnant women should eat no more than four medium cans or two fresh tuna steaks a week. Tuna contains more mercury than most other fish.

CCEA A-Level Nutrition and Food Science 3310

Protein

Topic overview Functions of protein Amino acids, biological value and complementation Animal and plant sources of protein Novel protein sources Nitrogen balance and protein requirements

Fat

Topic overview Functions of fat Structure of fats and fatty acids Saturated and monounsaturated fatty acids Omega-3, omega-6 and trans fatty acids Essential fatty acids

Carbohydrate

Topic overview Sources and functions of carbohydrate Intrinsic, extrinsic and non-milk extrinsic sugars Starch and resistant starch Non-starch polysaccharides and dietary fibre Blood sugar, glycaemic index and glycaemic load

Vitamins

Topic overview Vitamin solubility, absorption and bioavailability Vitamin A and beta-carotene Vitamin D and sunlight Vitamins E and K Thiamin, riboflavin and niacin Vitamin B6, vitamin B12 and folate Vitamin C and scurvy

Minerals

Topic overview Calcium and phosphorus Magnesium, sodium and potassium Iron and iron deficiency anaemia Iodine and fluorine Selenium and zinc Mineral bioavailability and absorption

Water and Other Fluids

Topic overview Functions and sources of water Nutritional benefits of other drinks Factors affecting hydration Dehydration and water intoxication

Nutrition Through Life

Topic overview Pre-conception and pregnancy nutrition Lactation and infant milk feeding Weaning and pre-school children School-age children and teenagers Nutrition for adult men and women Older adults and the frail elderly Dietary Reference Values and diet evaluation

Eating Patterns

Topic overview Food consumption trends and demographic change Social change, employment and leisure patterns Resources and availability of healthy food Food labels and advertising as barriers

Energy and Energy Balance

Topic overview Why the body needs energy Basal metabolic rate and physical activity level Energy EARs through life Energy balance and weight change

Overweight and Obesity

Topic overview BMI, waist circumference and measuring body fat Trends in childhood and adult obesity Barriers to achieving a healthy weight Health problems of excess weight Achieving a healthy weight in children and adults

Cardiovascular Disease

Topic overview Defining CVD and how atherosclerosis develops Non-modifiable risk factors for CVD Smoking, inactivity, alcohol, obesity and Type 2 diabetes Blood cholesterol, fatty acids and soluble fibre Hypertension, sodium, antioxidants and homocysteine Preventing CVD through diet and lifestyle

Cancer

Topic overview Cancer and how tumours develop Fat, salt and meat in cancer risk Wholegrains, fruit, vegetables and antioxidants Lifestyle factors in cancer risk Recommendations to reduce cancer risk

Type 2 Diabetes

Topic overview Definition and symptoms of Type 2 diabetes Risk factors for Type 2 diabetes Preventing Type 2 diabetes Managing Type 2 diabetes

Alcohol

Topic overview Units, energy and alcohol's link to obesity Alcohol, the heart and cancer Alcohol in pregnancy and the developing baby Nutritional effects of heavy drinking

Physical Activity

Topic overview UK physical activity guidelines Activity, heart health and energy balance Bone, joint, muscle and mental health benefits

Food Security and Food PovertyOption A

Topic overview Food security and the threat from climate change Land degradation and population growth Food poverty as a global issue Food poverty in the UK and Northern Ireland Food banks, FareShare and the Trussell Trust

Food SustainabilityOption A

Topic overview Animal farming, climate change and natural resources Local and seasonal food Organic farming and the environment Fairtrade and producer countries Red Tractor, NI Beef and Lamb, LEAF and Conservation Grade Carbon labels, Rainforest Alliance, MSC and green claims

Food WasteOption A

Topic overview Environmental and ethical impact of food and packaging waste Waste from primary producers and food manufacturers Waste from retailers and consumers WRAP, the Courtauld Commitment and Love Food Hate Waste NI

Changing Consumer BehaviourOption A

Topic overview Advice for sustainable food choices Barriers to sustainable food choices Environmental and social cost of supermarket shopping

Food Safety Through the Food ChainOption B

Topic overview WHO and shared responsibility for food safety Animal and plant health risks The Food Standards Agency and DAERA GMP, quality assurance standards and traceability HACCP in food-serving establishments Hygiene ratings, food law inspections and EHPs

Microbiological ContaminationOption B

Topic overview Salmonella and Campylobacter Listeria and Escherichia coli High-risk foods for food poisoning Microbial control by producers and manufacturers Microbial control in catering and at home

Chemical ContaminationOption B

Topic overview Acrylamide in cooked foods Arsenic in rice Bisphenol A and dioxins Mercury, lead and cadmium in food

Food AdditivesOption B

Topic overview Additive regulation and E numbers Food colours and flavour enhancers Intense and bulk sweeteners Preservatives, nitrites and sulphites

Food AllergensOption B

Topic overview Why food allergies are increasing Allergen labelling and information rules The FSA's work on allergy and intolerance

Food Safety Controls and LegislationOption B

Topic overview EFSA and food risk assessment General food hygiene under Regulation 852/2004 Regulation 853/2004 and official controls

Research Skills

Topic overview Primary and secondary research Questionnaires and interviews Food diaries, observation and sensory evaluation Sampling and research ethics Evaluating and referencing sources Analysing and presenting data

Chemical Contamination

Mercury, lead and cadmium in food

3 things to know
A2 1

Overview

Methylmercury in predatory fish and UK advice in pregnancy, the Minamata disaster, lead sources and effects on children, cadmium and itai-itai disease, and controls on heavy metals.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Where does lead exposure come from, and why is lead especially harmful to children?

Key term

Why are heavy metals a concern in food?

Key term

How does mercury reach fish?

Questions from this subtopic

Each one with the model answer underneath.

1
Why are heavy metals a concern in food?
Model answer
Heavy metals are toxic even at low levels and are not broken down in the body. Heavy metals accumulate in organs over time.
2
How does mercury reach fish?
Model answer
Mercury released by coal burning and mining settles into water. Bacteria convert mercury to methylmercury, which builds up through aquatic food chains.
3
Why do large predatory fish carry the most methylmercury?
Model answer
Methylmercury biomagnifies, increasing in concentration at each step up the food chain. Long-lived predators such as shark, swordfish and marlin accumulate the highest levels.
4
What are the health effects of methylmercury?
Model answer
Methylmercury is a neurotoxin that damages the brain and nervous system. The developing brain of an unborn baby is most sensitive.
5
What does UK advice say about eating shark, swordfish and marlin?
Model answer
Pregnant women, women trying to conceive and children should avoid shark, swordfish and marlin. Other adults should eat no more than one portion a week.
6
What limit on tuna is advised during pregnancy, and why?
Model answer
Pregnant women should eat no more than four medium cans or two fresh tuna steaks a week. Tuna contains more mercury than most other fish.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

See a huge jump in your memorisation

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Protein

Fat

Carbohydrate

Vitamins

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

Nicotine also blood vessels.

narrowsrelaxesreleases

Blank Blitz consolidates the facts

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe man's intake is 75% of the RNI.

BThe working is 30 ÷ 40 × 100 = 75%.

CThe intake is well above the LRNI.

Build It trains answer structure

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Overweight means an adult BMI from 25 up to 29.9.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Chemical Contamination, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.