Many food items sold in some of the most popular kitchen markets in the capital city have high concentration of substances that can be detrimental to human health, a study has found.
The study titled “Consumption of unsafe foods: heavy metal, mineral and trace element contamination,” conducted by Bangladesh Agricultural University (BAU), examined samples from the kitchen markets in Gulshan, Karwan Bazar and Hazaribagh and attributed the concentration on food chain contamination by heavy metals to the accumulation in biosystems through contaminated water, soil and irrigation water.
It detected at least one or more heavy metals – cadmium, arsenic, lead, mercury, antimony, nickel, aluminum and lithium – in five out of 16 food groups – cereals, fish, meat, vegetables and spices.
Concentration of minerals – calcium, magnesium, sodium and potassium – and trace elements – iron, manganese, copper, zinc, molybdenum, cobalt and selenium – varied widely across the foods and markets considered.
“As contamination does not show a clear pattern by market, purchasing food in wealthier markets [those in Gulshan] does not guarantee access to safe food,” said M Rafiqul Islam, professor of soil science at BAU who led the study conducted in late 2012.
“Findings signal that traders are not able to deliver safe food in the market … most likely due to the difficulty of recognising which foods are safer,” he added.
The concentration of heavy metals in rice appears to be high, influenced by the cooking technique, lower for draining and higher for absorption methods. Muri – puffed rice – has higher concentration of sodium, potassium, iron, manganese and aluminum than ordinary rice.
Arsenic content appears higher in fine rice than coarse rice in Gulshan compared to Karwan Bazar and Hazaribagh.
The research says that all households are at high risk of violating the FAO/WHO (2010) “Zero” provisional Tolerable Weekly intake for arsenic and lead.
Cereals and fish contribute to 98% of the total intake of arsenic by both poor and non-poor households. Non-poor households have a higher risk exposure to arsenic contaminated rice.
Cadmium concentrations were highest in Rui and Ilish sold in the Hazaribagh market, with Ilish having almost twice the concentration at Karwan Bazar and Gulshan markets.
Poor households are at risk of minerals and trace element deficiency, but levels of manganese and molybdenum are above the recommended daily intakes, the study says.
Professor Rafiqul Islam suggested that the authorities should develop rice varieties that accumulate less arsenic and cadmium to minimise the transfer from irrigation water to the grains and from grains to the body.