PANAJI
Edible oysters collected from the the Zuari bay at Agassaim were found to have a high presence of the heavy metal Cadmium in some cases up to five times the permitted concentration, a study conducted in December 2015 by the National Institute of Oceanography has found.
Interestingly, however the study has found that the concentration of Cadmium (Cd) is high even as its presence in the surrounding sediments is well within limits.
“The permitted Cadmium for edible oysters is 2mg per kg according to the US standards and 1mg per kg according to the Australia, New Zealand and Hong Kong standards. However, our study has found that the Cadmium in oysters found in the Zuari bay ranges between 3.2 mg per kg to 11.8mg per kg,” Dr Parthasarthi Chakraborty the lead researcher for the study has said.
“However in the sediment Cadmium was found to be within the limits -- ranging from 0.2 mg per kg to 0.5 mg per kg which classifies it as pristine or unpolluted sediment,” he said.
Chakraborty and four other researchers have authored the research on “Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oysters.”
He said that the higher concentration of Cadmium in the edible oyster could be explained by the stability of Cadmium in the sediment and its bioaccumulation in the oyster.
“Weak or unstable Cadmium complexes have a higher bioavailability and are hence more likely to accumulate in the oyster flesh,” Dr Chakraborty said adding that the total Cadmium concentration in sediment was not good indicator of the
bioavailability.
Dr Chakraborty and his team are also studying the seasonal variations of the presence of Cadmium in the oysters in order to ascertain if there is a ‘safe’ season of the year to eat oysters.
NIO STUDY: LIVER,
KIDNEY AT RISK
Cadmium in one’s diet can accumulate in the liver or kidney causing complications
For smokers, cadmium in diet along with that found in cigarettes makes it a deadly combination
The source of Cadmium, whether it is from natural or man made sources, is yet to be ascertained
WHAT ARE SAFE
CADMIUM LEVELS
For edible oysters 2mg per kg according to the US standards
HIGH LEVELS IN ZUARI OYSTERS
Cadmium in oysters found in the Zuari bay ranges between 3.2 mg per kg to 11.8mg per kg
