[Food Safety & You] Lead – Heavy Metal that invades our lives (Part 2)
Metallic Contaminant – LEAD
Lead is a naturally occurring but highly toxic heavy metal found in vehicle exhausts, cigarette, incense/ candle burning, paints, petrols, factory chimneys, plumbing pipes, faucets, storage batteries, etc. According to the World Health Organization, lead is a cumulative toxicants mainly stored in teeth and bones that is particularly harmful to young children. There is no “safe” level in human for lead and hence the lower the exposure and accumulated amount, the better.
What it does to the body?
According to International Agency for Research on Cancer (IARC), Lead is Class 2A Carcinogen, meaning that it is probably carcinogenic to human. “Lead” has different health impacts on children and adults.
For children, it can cause neurological impairment, coma and convulsions at high level of exposure in serious cases, and reduced Intelligence quotient (IQ), reduced attention span and behavior disorder at lower level of exposure.
For adults, exposure could cause anemia, increased blood pressure and kidney damage.
What is the main dietary source of exposure of lead?
SURPRISE! Our lead intake from diet comes mostly from VEGETABLES.
According to the study by the Centre for Food Safety, the sources of lead intake and the corresponding percentages of total exposure are:
| Dietary source of lead | % of total exposure |
| Vegetables | 30% |
| Non-alcoholic beverages | 16% |
| Mixed dishes | 14% |
| Cereals | 13% |
| Fish & seafood | 9% |
| Fruits | 6% |
| Meat & poultry | 6% |
| Legumes, nuts, seeds | 2% |
| Condiments, sauces, herb | 1% |
| Dairy products | 1% |
How to reduce Lead exposure?
1. Soak and wash vegetables (especially leafy vegetables) in water before cooking can remove significant amount of the remaining lead-contaminated dust and soil on the surface.
According to a research done by the Food and Environmental Hygiene Department (FEHD) of Hong Kong Government, soaking and washing reduced lead in leafy vegetables by 61% on average.
However, there was only 12% reduction of lead after boiling in water without soaking and washing.
2. More fruits instead!
Fruits also provide the healthy elements vegetables could offer, i.e. dietary fibre, antioxidants and vitamins.
Fun Fact about lead:
1. Matcha or Green tea?
Matcha actually contains 30 times more lead than green tea. It is because 90% of the lead in green tea stays in the leaf, which would be discarded while whole leaf of matcha is blended and consumed.
2. Tumeric: Real or fake yellow?
Tumeric, a commonly used healthy spice, may contain dangerous level of lead because lead chromate is sometimes added to turmeric power on purpose to make it more yellow.3. Century egg is a big NO?
Although lead oxide is used traditionally in the production of lime-preserved egg to accelerate coagulation, alternatives like zinc oxide and copper sulphate (which are essential micronutrients) are also introduced to substitute lead oxide in the production.
3. Century egg is a big NO?
Although lead oxide is used traditionally in the production of lime-preserved egg to accelerate coagulation, alternatives like zinc oxide and copper sulphate (which are essential micronutrients) are also introduced to substitute lead oxide in the production.
Ref: Centre for Food Safety, ConsumerLab, Food and Environmental Hygiene Department, International Agency for Research on Cancer, PMID: 15998560, 31550596, World Health Organization