y***u
发帖数: 7039 | 1 看了基本上所有的讨伐转基因玉米诱导癌变的评论，大部分都比较粗浅，不具有科学价
值和说服力。
下面这片比较客观， 就像作者所说的，对此课题比较熟悉。 认为作者有新的发现，
统计方法有效，实验结果具有价值。
Jack A. Heinemann
Centre for Integrated Research in Biosafety, School of Biologial Sciences,
University of Canterbury, Christchurch, New Zealand
Food and chemical toxicology, Volume 53, March 2013, Pages 442
Dear Editor
I have carefully read the paper entitled “Long term toxicity of a Roundup
herbicide and a Roundup-tolerant genetically modified maize”. I am very
familiar with historical publications on this topic.
A number of criticisms of this paper have appeared in the media. They
appeared shockingly quickly which caused me concern because I find it takes
more time to properly and thoroughly read a scientific paper of this
complexity. Most criticisms were of a general nature and without substance
worthy of entering the scientific debate. Some criticisms were specific,
referring to the type of rat used, the kind of statistical analysis, and the
interpretation of the response to increasing concentrations of the
agrichemicals, Roundup, or genetically modified plant ingredient.
I performed a quick review of papers on rat feeding studies using
genetically modified feed components also published in this same journal. In
addition to the paper by Seralini et al., I found seven studies between
2004 and now all published in Food and Chemical Toxicology in which Sprague
–Dawley rats were fed diets supplemented with material from GM plants. All
of these papers were published by those companies who developed the GM plant
used in the study. One paper was from Monsanto, and the others from DuPont/
Pioneer. None of the papers extended beyond ～90 days.
These studies used approximately the same number of rats as the study by
Seralini et al. All of them used the same kind of rat as the Seralini et al.
study. The 2004 study by Hammond used marginally more rats in the relevant
control group, but was in my opinion less powerful statistically because of
the inclusion of ‘reference’ control lines that were not fed on the near-
isogenic non-GM diet. The power gained by the additional rats (20/sex vs. 10
/sex) was offset by the noise introduced by irrelevant variables.
The statistics used in these other studies passed anonymous peer-review.
Aside from that, there is no other peer-reviewed evidence that these
statistical approaches are either uniquely appropriate or validated for
their use in this kind of study. On those fronts, I find Seralini et al.’s
statistical analysis equally valid. I would encourage both the scientific
community and the regulatory community to engage in an exercise of
validation of statistical analyses if this remains an issue of contention.
Where the Seralini et al. study has no peer in this group of papers is in
its duration. No number of 90 day feeding studies can refute the findings of
a long term study when the effects are largely those that appear after 90
days.
Some critics have attempted to disparage the most recent findings by drawing
doubt on the nature of the response, pointing out that the severity of the
effect did not uniformly increase with dosage. I am aware of a number of
toxicological studies that report similar phenomena. For example, Welshons
et al. (2003) said in their article in Health Perspectives: “Furthermore,
receptor-mediated responses can first increase and then decrease as dose
increases, contradicting the assumption that dose–response relationships
are monotonic.” The effect fits perfectly well with receptor-mediated or
saturated effects and within the hypotheses presented by Seralini et al.
While there is always room for more science on any topic, in my opinion the
Seralini et al. study stands shoulder to shoulder with the best of those
published by others on this same issue. Importantly, it explores hypotheses
that industry-based authors largely did not and therefore these earlier
studies are in no way evidence against the most recent findings. The proper
pathway forward is for any uncertainty in the findings to be put to rest
through: the establishment of a consensus protocol developed through a
transparent and openly peer-reviewed methodology; definitive study using
this protocol to be conducted by industry-independent scientists of
appropriate qualifications, such as Seralini et al., with reasonable access
for observation by those nominated by the industry and regulatory
communities.
In the meantime, it is my view that the recent study is a valuable
contribution to the scientific literature, debate and process of evaluating
technologies. I trust your journal to publish quality science and you have
vindicated my trust.
Reference
Welshons et al., 2003
W.V. Welshons, K.A. Thayer, B.M. Judy, J.A. Taylor, E.M. Curran, F.S. vom
Saal
Large effects from small exposures. I. Mechanisms for endocrine-disrupting
chemicals with estrogenic activity
Environ. Health Perspect., 111 (2003), pp. 994–1006 |
