Chloramphenicol policies, testing challenged

REGULATION aquaculture news from southeast asia Daniel Fegan
Chloramphenicol Policies,
Shrimp Biotechnology ProgramNational Center for Genetic Testing Challenged
Antibiotic residues in shrimp, and chloramphenicol in particular, have been big issues in Asia recently, due to the European Union’s implementation of both “zero tol- erance” and enzyme-linked immuno-assay (ELISA) testing for chloramphenicol residues. In early January, the E.U.
voted to ban imports of shrimp from China after the detec-tion of chloramphenicol in this and other animal products, evidence, although measures can be adopted on a provi- and concerns over the use of such banned substances in China. sional basis and then revised when more information is This move was quickly followed by action in the Unit- ed States, which stepped up inspections of Chinese seafood.
Since then, the detection of chloramphenicol has led to im- Acceptable Risk
poundment and destruction of shipments from several Asian Under the SPS agreement, countries are also free to es- countries, including Vietnam and Thailand, which cost sea- tablish their own levels of acceptable risk. They can adopt a more stringent level than that which is recognized inter-nationally, as long as they can demonstrate the internation- Concerns in Asia
al standard would not achieve their acceptable risk levels. Fishery authorities in most Asian countries have ex- pressed concerns about the E.U. action, with some suspect- Risk Assessment
ing it is being used as a barrier to trade. In a keynote speech Finally, the agreement requires that SPS measures be at the ASEAN Fisheries Federation Meeting on Chloram- based on an analysis and assessment of risks to life or phenicol held in Jakarta, Indonesia in January, Dr. Rokhmin health, and the probability of adverse effects on human or Dahuri said the chloramphenicol issue was an example of animal health from additives, contaminants, toxins, or dis- how some developed countries systematically use nontariff barriers as disguised restrictions to trade. Dahuri, Indone-sia’s minister of marine affairs and fisheries, questioned Zero Tolerance
whether the action was a measure intended to protect con- To date, neither the Joint Expert Committee on Food sumers’ health or pretext to impose a technical barrier to trade.
Additives and Contaminants nor the Codex Committee onFood Additives and Contaminants has established maxi-mum residue limits for chloramphenicol. In this situation,the E.U. is within its rights to establish its own level of ac-ceptable risk. On the basis of the SPS agreement, however, it has been questioned whether “zero tolerance” is a fair level of ac-ceptable risk. Zero tolerance has been likened to a require-ment for “zero risk,” which is not acceptable as a basis forimport prohibitions, since it effectively negates the needfor an import risk assessment. There is some degree of riskassociated with most, if not all imports. Detection Limits
In the past, the maximum residue limit was set in prac- Alliance. Do not reproduce without permission.
tice by the limits of detection for the tests used. Changingfrom high-performance liquid chromatography (HPLC) to Backed by lab results, shrimp exporters are questioning the ELISA testing effectively reduced detection limits from 10 results of new test procedures used to detect chloramphenicol. Aquaculture
WTO Position
ELISA Testing Questioned
The World Trade Organization Agreement on the Appli- Both the increased sensitivity and reliability of the cation of Sanitary and Phytosanitary Measures (SPS) ac- ELISA test have been questioned. Several instances have cepts the rights of countries to adopt and enforce measures been cited of different laboratories reporting different test to safeguard human, animal, and plant health. However, results, raising concerns about the reproducibility of the test. such measures should not be applied in a manner to consti- Several Asian exporters have gone to great expense to tute a disguised restriction on international trade. They buy equipment and set up the capability for routine chlo- Copyright 2002, Global
should also not be maintained without sufficient scientific ramphenicol testing by ELISA. In the past, this allowed ex- THE ADVOCATE APRIL 2002
porters to ensure that the product they bought met the stan-dards required by their customers. Chloramphenicol Effects
on Humans
Reliability
However, experience in the present case has shown that The major risk to human safety from chlorampheni- negative tests in the processing plant do not necessarily col exposure is through its role as a precursor to aplastic mean subsequent testing in the importing country will also anemia. Aplastic anemia occurs when bone marrow prove negative. More than one exporter has questioned the produces too few blood cells. The reduction in red blood reliability of the method, given its high cost and uncertain cells causes hemoglobin levels to fall, while reduced numbers of white blood cells increase susceptibility toinfection. A fall in the number of platelets affects clot- Other Concerns
The increased sensitivity of ELISA tests has also raised Aplastic anemia has several causes, some sporadic doubts about their use in the context of zero tolerance and and others that follow predisposing conditions. Among trade. Tests conducted in Thailand by Prof. Piamsak Mena- sveta of Chulalongkorn University and by other laborato- • Infectious diseases (e.g., infectious hepatitis)
ries on a range of food items purchased locally showed that • Medication (antibiotics and anticonvulsants)
ham, caviar, butter, and anchovies from Europe – as well as • Toxins (heavy metals)
similar items from other countries – have chloramphenicol • Radiation
levels detected by ELISA at up to 1.38 ppb. • Autoimmune disease
Positive tests for chloramphenicol in wild-caught squid have also been reported, which may indicate a detectable • Inherited conditions.
background contamination in nature or the possibility of Chloramphenicol-related aplastic anemia is dose- cross-reactivity of the test. It is clear a number of issues related, varies from person to person, and is usually re- concerning the application of ELISA tests must be resolved. versible. The worldwide annual incidence of aplasticanemia has been estimated at 2-6 cases/million people.
Conclusion
Geographical differences in prevalence, with greater Given the importance of the seafood industry to Asian occurrence in Asia than the West, suggest that environ- countries, the ASEAN Fisheries Federation has asked the mental factors may also be involved.
European Union to consider the gradual application of itszero-tolerance requirement over a five-year period, and The major risk to human safety
joint research by scientists from the E.U. and ASEAN coun- from chloramphenicol exposure
tries to determine if the zero-tolerance approach is justified.
The detection of chloramphenicol residues in consumer is through its role as a precursor
food products from the E.U. and other countries also sup- to aplastic anemia.
ports the call for further study and a harmonized interna-tional standard to avoid unfair trade restrictions.
78 THE ADVOCATE APRIL 2002

Source: http://pdf.gaalliance.org/pdf/GAA-Fegan-Apr02.pdf