ANALYSIS: Academics lambaste US¡¦
ractopamine safety data
By Shih Hsiu-chuan / Staff Reporter
Swine farmers preparing a trip to
Taipei hold up signs opposing a relaxation of the ractopamine ban after a
preparatory meeting in Chiayi County on Thursday.
Photo: Hsieh Yin-chung, Taipei Times
Local experts in hygiene and veterinary
medicine have urged the US to squarely face the challenges posed by the
scientific evidence on which it has based its contention that US beef containing
the lean meat-enhancing feed additive ractopamine is safe for human consumption,
before it presses Taiwan to handle the issue scientifically.
In a rare address to local media, the American Institute in Taiwan (AIT) on Feb.
22 issued a communique to counter published ¡§misinformation¡¨ which called into
question the US¡¦ argument that levels of ractopamine residue in meat permitted
in other countries were safe for human consumption.
The statement was followed by a second one released on Thursday, in which it was
argued that the feed additive is not only safe, but also necessary to ¡§boost
production to meet growing world demand for meat, while keeping consumer prices
at reasonable levels.¡¨
Drawing mainly on the study by the Joint Expert Committee on Food Additives (JECFA),
which serves as a scientific advisory body to the UN¡¦s Food and Agriculture
Organization, the WHO and the Codex Alimentarius Commission ¡X the international
food standards body ¡X the AIT said it wished that the Taiwanese media could do
justice to US beef.
The AIT also wished the media to note that the EU and China were mostly
influenced by ¡§non-scientific factors¡¨ when they opposed the use of ractopamine
and that Taiwan has its own assessment of ractopamine, done in 2007, which found
ractopamine was safe for use.
However, Chan Chang-chuan (¸âªøÅv), a professor at National Taiwan University¡¦s
Institute of Occupational Medicine and Industrial Hygiene, rejected the US¡¦
arguments after reviewing the AIT communiques.
¡§When it comes to science, only one truth will prevail,¡¨ Chan said in an
interview with the Taipei Times.
International opinion, based on analyses of scientific papers on the effects of
ractopamine on humans, remains divided, he said.
¡§Given the situation, how could the AIT use one-sided statements to bamboozle
Taiwanese into thinking that ractopamine in US beef poses no health risk?¡¨ he
asked.
The AIT says that the EU did not adopt a scientific approach because it banned
the use of beta-agonists, the class of drug to which ractopamine belongs, long
before ractopamine was introduced to the market.
¡§The EU did not conduct any studies on ractopamine prior to adding it to the
list of already-banned beta-agonists,¡¨ the communique said.
Chan disagreed with the ¡§non-scientific¡¨ label attached to the EU¡¦s viewpoint.
It is true the EU did not conduct its own risk assessment of ractopamine, Chan
said.
¡§This is because the EU generally prohibits the use of beta-agonists, and with
that the EU did not consider that it was obliged to do a risk assessment.
However, the EU ordered the formation of a task force to provide scientific
opinions on the safety of ractopamine,¡¨ he said.
The EU then raised many scientific grounds for concern over the safety of
ractopamine, based on the 52-page report presented by the task force ¡X the Panel
on Additives and Products or Substances used in Animal Feed (FEEDAP) ¡X in 2009,
Chan said.
¡§It¡¦s OK that the US disagreed with the EU, but the US can¡¦t say the EU cited
¡¥non-scientific factors¡¦ as the basis for its opposition to ractopamine,¡¨ he
said.
In 2004, the JECFA established an accepted daily intake (ADI) of 300g of muscle,
100g of liver, 50g of kidney and 50g of fat, and recommended maximum residue
levels (MRLs) of ractopamine of 10 parts per billion (ppb) in muscle and fatty
tissues, 40ppb in livers and 90ppb in kidneys in cattle and pigs for
consideration by the Codex Committee Commission.
The recommendations have been stuck at the final stage in the Codex process
since they were proposed in 2008.
The FEEDAP report raised several technical questions on the JECFA study, which
concluded that a dose of 5mg of ractopamine, the lowest administered dose in its
human study, could be considered a no-effect dose, as it did not cause any
cardiovascular response.
¡§The human study cannot be taken as a basis to arrive at an ADI and consequently
no proposal for MRLs could be made,¡¨ the FEEDAP report concluded.
Among the findings in the FEEDAP analysis were: The available human data was
pivotal to assess consumer safety, because data from laboratory animals gives a
wide range of susceptibility of various animals to ractopamine; and the sample
size of six subjects in the human study did not provide sufficient statistical
power to detect a clinically relevant response that would be statistically
significant.
The FEEDAP also said that the use of the data obtained from the JECFA¡¦s human
study ¡§exposes experimental weaknesses and uncertainties,¡¨ because it was
originally designed to establish dose-effect responses to enable suitable doses
to be selected for a larger study and not to define a no-effect level, and thus
¡§limits the conclusiveness of the study.¡¨
It was of concern to the panel that the safety factor applied by JECFA to arrive
at the ADI did not sufficiently take into account population subsets at higher
risk.
¡§Those are all important questions. The US should let people know how they
answer these questions. Taiwan should also reference EU studies,¡¨ Chan said.
Chou Chin-cheng (©P®Ê¼á), dean and chairman of the Institute of Veterinary Clinical
Science at National Taiwan University¡¦s School of Veterinary Medicine, shared
Chan¡¦s view, saying the JECFA scientific evidence provided by the US remained
insufficient and unconvincing.
¡§In principle, scientific theories, unlike beliefs, are subject to question and
development or refutation by the accretion of evidence,¡¨ Chou said.
The JECFA argument remains weak and relatively unproven, because the FEEDAP has
pointed out fatal flaws in the research, but over the years, when the issue was
debated at Codex meetings, both the JECFA and the US avoided the issue, he said.
For example, the JECFA could have carried out an experiment to measure
ractopamine residue in lungs in response to China¡¦s concerns, but it just
downplayed the issue, he said.
China proposed three residue depletion studies on ractopamine in pig tissue in
2009 and an experimental study on ractopamine residue in pig tissue in 2010 over
concerns that residue levels in lung, stomach, heart, large and small intestine,
which are important cuts in the diet of Asian consumers, were left out of
consideration by the JECFA.
In line with its findings that the residue in lungs, the stomach, and the large
and small intestines is at a high level, China concluded that the ADI
recommended by the JECFA was not acceptable.
In 2010, the JECFA deferred recommending an MRL for lung tissue and suggested
that further study regarding the consumption of lung tissue might be warranted.
As for other animal organs of concern to China, the JECFA said they were safe
for human consumption, as its assessment that substituted other organ data in
the model diet found that the resulting dietary intakes were below the upper
boundaries of the ADI.
In response to the AIT¡¦s suggestion that Taiwan should revise its zero-tolerance
policy on ractopamine in line with its own 2007 risk assessment, both Chan and
Chou said the paper is ¡§of little value¡¨ as a reference.
The eight-page paper was just ¡§a first step of a complete risk assessment,¡¨ they
said.
According to the two experts, the local study did not include an experimental
study and the research was not comprehensive.
It was fraught with flaws. For instance, it drew on census statistics produced
in 1982 and it failed to take into account subpopulations which might be at a
higher risk for adverse drug events caused by ractopamine, they said.
In the AIT communique, it cited ¡§ethical reasons¡¨ to reject the criticism over
the small sample size of six subjects in the JECFA¡¦s human study, to which Chan
responded by saying: ¡§Were there any adverse event, would it be more ethical?¡¨
The EU said the minimum acceptable sample size should be 60, Chan said.
Chan gave two examples to emphasize the importance of sample size.
¡§Before the indigenous vaccine invented to prevent the spread of the A(H1N1)
influenza virus was put into use in 2009, there were 300 people involved in a
human study. Even the recently published ractopamine experiments on pigs
conducted by the Animal Technology Institute Taiwan had a sample size of 64,¡¨
Chan said.
¡§How could a sample size of six human subjects provide sufficient statistical
power? Plus, they were all healthy males aged between 19 and 26,¡¨ Chan said.
Other than saying that more than 100 clinical studies and country-directed risk
assessments in 27 countries have documented that ractopamine was safe, the AIT
also dismissed the concerns over US beef¡¦s safety by highlighting that the
connection between consumption of meat with ractopamine and human health was
empirically unproven.
¡§The US exported beef and pork products to more than 100 countries around the
world in 2011. Over the past 10 years, millions of people have eaten billions of
kilograms of US beef and pork with no reports of illness or any other effect
linked to the consumption of meat from animals fed ractopamine,¡¨ the AIT said in
its second communique.
Both Chan and Chou strongly questioned the argument.
The EU has raised suspicions that the drug¡¦s manufacturer, Elanco, could have
falsified or withheld information about its safety and effectiveness, as well as
about adverse animal drug reactions, after which ractopamine was approved as
safe, Chou said.
Chou said the EU¡¦s concern has been borne out either by academic studies, mostly
published in the Journal of Animal Science, or by case reports of adverse drug
reactions.
¡§We have too little information to judge the safety of ractopamine. How much
more information against it was not made available? What were the indicators
used to evaluate the effects of ractopamine in the JECFA study and that were not
included? We know too little, so we should maintain the ban until the Codex
reaches a consensus,¡¨ Chou said.
Chan said the US contention that there had been no health problems associated
with eating US beef because no case had been reported was ¡§indefensible.¡¨
¡§There has never been any mechanism in place to monitor the effects of consuming
meat with ractopamine residue on human health. If you do not monitor it, how can
you know for sure there is no adverse event?¡¨ Chan said.
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