Environmental Risk
Assessment of Genetically Modified Organisms: Volume 1. A Case Study
of Bt Maize in Kenya
A.
Hilbeck and D. A. Andow
CAB
International, Wallingford, UK, 2004
304 pp., $110.00
ISBN: 0-85199-861-5
Maize is without question a tremendously important and popular crop
in Africa, a continent too often in the media, and so in our
psyches, associated with food shortages. Portuguese explorers
introduced maize to the African continent early in the 16th century,
and the first documentary evidence of its cultivation dates to 1540
(McCann 2005). Today, maize is the
single most planted cereal on the African continent and the second
most important food crop, behind cassava. It is grown in a wide
range of environments: from the dry Sahel and southern Africa to the
eastern highlands to the lowland tropics. Maize is extremely
popular, and not solely because of its palatability, but also
because of its high productivity and low labor demands, particularly
relative to sorghum and millet. It is easy to see why improving
maize productivity in Africa through biotechnology is a needed,
although often contentious, enterprise.
The Kenya Bt-maize risk assessment case study—prepared by a
formidable group of >50 scientists under the editorship of Andow and
Hilbeck—is thorough, rigorous, objective, and transparent. It was
organized by the Transgenic Organisms in Integrated Pest Management
and Biological Control working group of the International
Organization for Biological Control (IOBC), with funding from the
Swiss Agency for Development and Cooperation and assistance from the
Scientific and Technical Advisory Panel of the Global Environment
Facility. The book is divided into eight chapters: the first two
giving context to the case study, the next five addressing specific
aspects of the risk assessment exercise, and the final chapter
offering a synthesis of the study's findings and a series of
recommendations.
In
the opening chapter, Andow and Hilbeck unveil the goal of the
exercise, which was to "develop components of a scientific risk
assessment process, which (sic) are consistent with that
called for by the (Cartagena) Protocol (on Biosafety)… " (p. 1).
Also in this chapter, they briefly address a number of concepts
relevant to risk assessment (e.g., transgenesis, risk assessment,
valuation) and offer a concise overview of the book's content.
Information concerning maize production in Kenya in general, and
Bt-maize in particular, is presented in the chapter by Muhammad
and Underwood.
The third chapter, by Nelson et al., is a Problem formulation and
options assessment (PFOA) for Kenya Bt-maize. This is a very
informative chapter, particularly for those not familiar with risk
assessment procedures. While PFOA is undoubtedly a useful tool for
risk assessment in most natural resource contexts, its use in the
case of Bt-maize may be problematic. An important
characteristic of PFOA is that it can be applied iteratively so that
changes in public attitudes and advances in scientific knowledge
over time can be incorporated in its application: Once released into
the environment, however, Bt-maize transgenes cannot be
returned to laboratory confinement. Although a "trial run" (p. 62),
one significant caveat particular to the Kenya Bt-maize PFOA
is its narrow stakeholder representation consisting of eight Kenyan
and international scientists.
The fourth chapter, concerning Bt-maize transgene locus
structure and expression, by Andow et al., is excellent. It provides
a good and candid discussion, relevant to Kenya, of transgene
design, locus structure, expression, and transmission and lists a
number of important—including problematic—findings (e.g., available
Bt-maize events are likely ineffective against Busseola
fusca, one of the two most important stemborers in Kenya).
The fifth chapter, by Birch et al., is a thorough analysis of
potential effects and their likely pathways on nontarget organisms.
Particularly noteworthy of this chapter is a series of testable
hypotheses (and questions) that are presented related to the
potential hazards of Bt-maize identified by the authors. In a
subsequent section, the authors provide detailed methodologies for
testing most of the hypotheses. Some of the hypotheses and
methodologies are more fully dealt with than others (e.g., those
relative to stemborers and their parasitoids), which reflects
corresponding states of knowledge.
The likelihood of and risks associated with Bt-maize (trans)
gene flow is addressed by Johnston et al. Particularly notable of
this chapter are an extended list of questions guiding this
component of the risk assessment exercise and a section identifying
important knowledge gaps. One such gap, which is particularly
troubling—and was noted in passing by Muhammad and Underwood—is that
the amount of unique genetic diversity contained within the Kenyan
landraces is unknown.
The final component of the risk assessment exercise was prepared by
Fitt et al. and is composed of a detailed analysis of species at
risk, potential exposure routes, monitoring methods, possibilities
for resistance management, and other issues. A number of important
problems were identified that must be resolved before commercial
release of Bt-maize (e.g., none of the available Bt-maize
events is a high-dose event against the key stemborers in Kenya and
a number of farmer customs and attitudes), and the authors suggest
how these problems can be surmounted. In the final section of this
chapter, the authors present the components of a resistance
management strategy for Bt-maize in Kenya. The major themes
of the book are tied together in the final chapter, and the book
concludes with a short section offering a number of author
reflections, case study criticism, and questions for future case
studies.
A
number of observations scattered among the book's chapters left a
sensation reminiscent of a childhood adage: every object is a
nail in the eyes of a child holding a hammer (a poor translation
from Spanish). To wit, the most important constraints to maize
production in Kenya, as ranked by farmers, are unrelated to pests
(e.g., lack of cash, drought, poor seed quality), and the most
important pest problems to farmers are Striga, maize streak
virus, fungal pathogens, and stemborers (chapter 2). Of these pests,
the available Bt-maize events show "good efficacy" (p. 106)
only against one of the two key stemborer species, and none of these
events is high dose against Kenyan stemborers (chapter 7).
Furthermore, a substantial amount of past and still ongoing research
gives optimism that stemborers can be managed through biological
control and crop management strategies such as the "push-pull"
system (reference is made to both in chapter 2). Therefore, after
reading this book, at least two questions are left to ponder: is low
Kenyan maize productivity a true nail to our Bt-maize hammer?
And, more specifically, is Bt-maize, as currently available,
a real priority for reducing losses caused by maize stemborers in
Kenya?
References
McCann J. C. Maize and grace: Africa's encounter with a New World
crop, 1500-2000. Cambridge, MA, Harvard University Press, 2005.
Juilo Bernal
Department of Entomology, Texas A & M
University
College Station, Texas
Environmental Entomology
Vol. 35, No. 4, August 2006, Page 1139-1140
