GEORGE TOWN (THE STAR/ASIA NEWS NETWORK) - The United States Food and Drug Administration (USFDA) last year put many Malaysian shrimp exporters on a 'red list' after samples of 18 shipments from 11 Malaysian exporters were detected to contain chloramphenicol.
Between 2009 and 2018, the USFDA also put 28 Malaysian shrimp exporters on its red list because 56 shipment samples contained nitrofurans.
But while these exports are curbed, farmed shrimps sold locally face fewer checks, The Star found.
Malaysians are unknowingly consuming tainted shrimps which contain antibiotics - nitrofurans and chloramphenicol - that can lead to serious health issues.
And some of these shrimps - tiger prawns and Pacific whiteleg shrimps - can be commonly found for sale at most wet markets in Malaysia.
Market traders prefer to sell shrimps farmed in the wild, rather than farmed ones which could contain these antiobiotics.
For consumers like Dr P. Anita, 40, it doesn't hurt to be extra careful.
"It is easy to tell them apart. Wild shrimp are pink or pale and vary in sizes. Farmed ones are grey and are usually the same size. "
Consumer groups have warned for years the consequences of digesting such substances with our seafood but the public health issue continues to persist even now.
Experts believe that residues from these two antibiotics are carcinogenic.
In the case of chloramphenicol, it also leads to a rare but serious side effect of bone marrow failure, leading to the lack of production in red and white blood cells and platelets.
Penang has the highest number of such red-listed exporters.
Of the 28 Malaysian exporters red-listed by the USFDA for trying to send in shrimps containing nitrofurans, 19 are based in Penang.
Out of 11 that tried to export chloramphenicol-tainted shrimps, eight have Penang addresses.
The rest are in Perak, Selangor, Kedah and Sarawak.
A worker at a large shrimp farm in Kedah, who spoke on condition of anonymity, said about 10 years ago, a strange disease hit the shrimps.
"We called it the Early Mortality Syndrome . In just 30 days, nearly all of the shrimps died after being put in the growing ponds," he said, adding that farmed shrimps would usually take 70 to 100 days to reach harvestable sizes.
Farmers, he said, tried many types of medication but these all failed and so, they resorted to nitrofurans and chloramphenicol.
In Penang, though it is an island, over half of its seafood in 2014 came from aquaculture farms, found mostly along the Balik Pulau coast in the west.
But Deputy Agriculture and Agro-based Minister Sim Tze Tzin blamed Malaysia being red-listed on producers of antibiotic-tainted shrimp from other countries suspected of using Malaysia as a transit hub.
He said these Malaysian exporters could have been engaging in trans-shipment activities.
"Based on past cases, we believe that they imported frozen shrimp from other countries and re-exported them to the US.
"We have tightened our monitoring since then," he said.
Any shrimp farm intending to export their harvest must be registered with Fisheries Department, warned Mr Sim.
The Fisheries Department's Biosecurity Division also regularly took shrimp samples from these farms to test for antibiotics as well as heavy metals, hormones and dyes, he said.
"If the samples contain banned antibiotics, the farms will be sanctioned and their harvests will not be allowed to be exported," he said.
When contacted, the Singapore Food Agency (SFA) told The Straits Times on Monday that it has not detected chloramphenicol or nitrofuran in shrimps and prawns imported from Malaysia in 2019.
Even so, SFA said that it will continue to regularly monitor and sample imported seafood products, including shrimps and prawns, for testing to ensure that they meet its food safety standards and requirements.
The agency said that this includes ensuring the products do not contain drug residues that may be potentially harmful to human health.