Food Scares . . . time to call the bluff!!!
We are all familiar with the story of the boy who cried wolf merely to get attention. Certain media outlets do the same when it comes to food scares. Citizens react immediately out of fear; they stop eating the food. And when the Food Authority – the only source they can trust – stays silent, the news gains credibility. India has a modern science – based food law that requires the Authority to provide the scientific truth behind these scares – and quickly. Food scares recur all the time; not long ago pesticide residues raised a “safety concern” and now lead is making another comeback.
We would all love to eat food with ‘zero lead’ in it; however, this is highly unlikely with lead being an environmental contaminant. So scientific experts – the Joint FAO/WHO Expert Committee on Food Additives – assess the total amount of lead intake through the consumption of foods per week (exposure) that can be tolerated (provisional tolerable weekly intake or PTWI). In food law this is exposure assessment.
International scientific committees such as – Joint FAO/WHO Expert Committee on Food Additives (JECFA), Joint FAO/WHO Meeting on Pesticide Residues (JMPR), European Food Safety Authority (EFSA) and FSSAI use the safety factor approach for establishing acceptable or tolerable intakes. The safety factor is described by various terms; for example the “ADI” (acceptable daily intake) in the case of food additives, pesticide residues, veterinary drugs, and PTWI (provisional tolerable weekly intake) for contaminants, such as lead, arsenic or cadmium. The weekly designation is used to stress the importance of limiting intake over a period of time for such substances.
Image via iStock.com/pixelfusion3d
JECFA provides a PTWI of 25 micrograms per kg body weight (body weight for Indians 50kg) which means that the exposure intake per week should be below 1250μg (i.e. 1.25mg per week). Now we should know if this limit is exceeded on a weekly basis. For this the second piece of information is how much is the current exposure to lead through foods. A total diet study would provide this data, which is a mandate of the Act; and yet to be done. But a good indicator (total diet study approach) of food consumption is a study by NIN (IJFANS Vol.3, Iss.4, Jul-Sep 2014). A snapshot of the data is shown for illustration purposes in Table 1:
|Table 1: Food intake and mean concentration of lead in cooked foods|
|No.||Food||Mean Concentration (μg/kg of food)||Food Intake* (g)|
|* Values for sedentary worker (man) at 95th percentile|
Considering the lead concentration in foods (μg/kg) and the consumption of foods per day (g/day) one can obtain evidence whether the safety factor (PTWI) is exceeded or not. In the same study the mean exposure (intake) to lead consumed through food is 3.72 μg/Kgbw (14.9% of PTWI) and 7.28 μg/Kgbw (29.1% of PTWI).
So even at the highest level of consumption the exposure to lead is below the safety factor by one third. This is good science speaking and such data enables the Food Authority to provide consumers with the truth. The question remains; how does lead get into food and who is responsible?
Lead is ubiquitously present in air, water and soil from use of industrial products such as paints, petrol (previously), plumbing, solders, batteries, water pipes etc. Soil is contaminated with lead from past practices and continuing until a national effort for its reduction is taken up. Lead in then transferred to food crops – cereals, potatoes, leafy vegetables, spices, tap water (lead pipes) etc.; and every human is exposed to lead through the diet. There is no method to remove it from food except reducing its presence in our food production.
So when “ breaking news” on food scares is splashed on your TV screens – simply look for pieces of information. Just tell us the facts; how much of the undesirable substance we consume through foods and whether it exceeds the safety factor.
Thank you Dr. Lewis for bringing out the factual information!