No Detection of Cry1Ac Protein in Soil After Multiple Years of Transgenic Bt Cotton (Bollgard) Use

Head, Graham P.; Surber, James B.; Watson, Jon A.; Martin, John W.; Duan, Jian J.

doi:10.1603/0046-225x-31.1.30

Cited by 131 publications

(137 citation statements)

References 21 publications

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“…Subsequent studies under conditions more relevant to agricultural fields have supported earlier conclusions about the degradation of Cry1Ac with a half life of approximately 9-40 days (Accinelli et al, 2008;Marchetti et al, 2007). In at least one field experiment, Cry1Ac was not detected by ELISA or bioassay in agricultural fields where Cry1Ac expressing cotton (MON-00531-6) had been grown and tilled into soils for three to six consecutive years (Head et al, 2002). Regulatory approvals of Cry1Ac events have considered information on Cry protein rates of degradation in a range of soil types, but have not required additional soil organism toxicity testing for Cry1Ac (CFIA, 1997;CTNBio, 2005;Japan BCH, 1997, 2007OGTR, 2002aOGTR, , 2003bOGTR, , 2003cOGTR, , 2005OGTR, , 2006bUSDA APHIS, 1994, 1997a, 1997b, 1997cUSEPA, 2001).…”

Section: Routes Of Environmental Exposurementioning

confidence: 52%

A review of the environmental safety of the Cry1Ac protein

Lean¹

2011

Environ. Biosafety Res.

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1 Event refers to a single transformation event: the incorporation of a transgene into a plant genome. A single transformation event can be crossed into multiple lines.2 Tomato Event 5345 expressing Cry1Ac was deregulated by USDA APHIS but never received registration as a pesticide with the USEPA and was not commercialized anywhere in the world. It will not be considered elsewhere in this paper. 3 This includes approvals for lines generated through breeding and transformation with additional transgenes.

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Section: Routes Of Environmental Exposurementioning

confidence: 52%

A review of the environmental safety of the Cry1Ac protein

Lean¹

2011

Environ. Biosafety Res.

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“…For example, Zwahlen et al (2003a) reported δ-endotoxin declining to 38% within 40 d during the fall and it still being detectable at 0.3% of the initial concentration after 200 d in temperate conditions in Switzerland (where the soil temperature fell below 0°C between December and March), whereas in a study using Bt-cotton (which is grown in warmer climates than central Europe or Canada), Head et al (2002) did not detect δ-endotoxin in soil after approximately 90 d after harvest.…”

Section: Comparison Of δ-Endotoxin Decomposition and C Mineralizationmentioning

confidence: 99%

Decomposition of residues and loss of the δ-endotoxin from transgenic (Bt) corn (Zea mays L.) in soil

Hopkins

Gregorich

2005

Can. J. Soil. Sci.

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. 2005. Decomposition of residues and loss of the δ-endotoxin from transgenic (Bt) corn (Zea mays L.) in soil. Can. J. Soil Sci. 85: 19-26. Corn and other crops genetically modified to express the insecticidal δ-endotoxin from Bacillus thuringiensis (Bt) are grown widely across north America. Studies have shown that the δ-endotoxin can be stabilised on soil colloids where its activity is retained, but reports of direct ecological effects of the δ-endotoxin on soil processes are limited. We have determined the concentrations of the δ-endotoxin in organic residues from Bt-corn plants at increasing stages of ageing and decay, and the subsequent decomposition in soil of these residues and the δ-endotoxin in them. The δ-endotoxin concentrations declined from 6.8 µg g -1 in the fresh plant material, to 0.82 µg g -1 in the post-harvest residues collected in the fall, and to 0.026 µg g -1 in the residues collected from soil surface the following spring. The concentration of δ-endotoxin in buried residues collected in the spring was not significantly different from zero. When incubated in soil in the laboratory over 84 d, the δ-endotoxin decomposed more rapidly than bulk plant C by factors of 1.85 for the fresh plant materials and 3.21 for the post-harvest residues. Within 14 d of incubation, the δ-endotoxin concentration in the residues collected at the soil surface was below the limit of detection. We contrasted the laboratory decomposition data with data from a field experiment to estimate the period that the δ-endotoxin in corn residues may survive in the field. Based on estimates derived from this comparison, we predict that following an October harvest in eastern Ontario the δ-endotoxin would fall below the detection threshold during November for post-harvest residues. Since stabilisation of the δ-endotoxin on soil colloids depends on it surviving (i.e., not being decomposed) for long enough to be released from the plant residue matrix and come into proximity with colloid surfaces, the rapid decay of the δ-endotoxin suggests that only a small fraction of the δ-endotoxin from post-harvest residues persists long enough to become stabilised in the field. Des études ont montré que la δ-endotoxine se stabilise sur les colloïdes du sol et garde son activité, mais on sait peu de choses au sujet de son incidence écologique sur les processus du sol. Les auteurs ont établi la concentration de δ-endotoxine dans les résidus organiques de plants de maïs Bt à différents stades de vieillissement et de pourrissement ainsi que la décomposition subséquente de ces résidus et de la δ-endotoxine dans le sol. La concentration de δ-endotoxine passe de 6,8 µg par gramme dans les tissus végétaux frais à 0,82 µg par gramme dans les résidus post-messianiques recueillis à l'automne puis à 0,026 µg par gramme dans ceux prélevés à la surface du sol le printemps suivant. La concentration de δ-endotoxine dans les résidus enfouis, prélevés au printemps, ne diffère pas significativement de zéro. Incubée pendant 84 jours dans le sol en laboratoire, ...

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“…These data predict that cultivation of GM plants containing these proteins is unlikely to lead to accumulation of transgenic proteins in the soil. This hypothesis has been corroborated by Head et al (2002) and Dubelman et al (2005), who showed that continuous cultivation of cotton containing Cry1Ac or maize containing Cry1Ab did not lead to the accumulation of the transgenic proteins in soil. These results were not surprising as most proteins do not persist or accumulate in soil because they are inherently degradable in soils that have healthy microbial activity (e.g., Burns 1982, Marx et al 2005, and references therein).…”

Section: Exposurementioning

confidence: 64%

Environmental Risk Assessment of Genetically Modified Crops: General Principles and Risks to Non-target Organisms

Raybould

2009

BioAssay

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Análise de Risco Ambiental de Plantas Geneticamente Modificadas: Princípios Gerais e Riscos aOrganismos Não-Alvos RESUMO -O presente trabalho discute que a análise de risco deveria ser abordada segundo o modelo de desenvolvimento contínuo do saber científico proposto por Karl Popper. Nesse contexto, a análise de risco deveria começar com o problema e busca de respostas para esse problema mediante testes de hipóteses. A análise de risco sendo considerada como teste de hipóteses, a segurança não pode ser provada, porém pode ser indicada pelos testes de hipóteses que prevêem baixo risco. A confiabilidade na análise de risco é dada pelo rigor com que hipóteses de risco são testadas; sendo que os testes devem ser iniciados em condições mais prováveis para demonstrar que as hipóteses de risco são falsas. Se as hipóteses de risco são corroboradas nessas condições, há confiança de que os riscos impostos pelas plantas geneticamente modificadas são baixos. O aumento no rigor nos testes de hipóteses auxilia para justificar o estabelecimento da solicitação de dados adicionais, e pode reduzir o risco ambiental mediante prevenção de atrasos excessivos no registro de produtos ambientalmente benéficos. PALAVRAS-CHAVE -Método científico, formulação de problema, teste de hipóteses.ABSTRACT -This paper argues that risk assessment should be viewed as conforming to the model of the continuous development of scientific knowledge proposed by Karl Popper. As such, a risk assessment should begin with a problem and search for answers to that problem by testing hypotheses. Regarding a risk assessment as hypothesis testing recognises that safety cannot be proved, but can be indicated by tests of hypotheses that predict low risk. Confidence in the risk assessment is provided by the rigour with which the risk hypotheses are tested; it follows that testing should begin under conditions most likely to reveal that the risk hypothesis is false. If the risk hypothesis is corroborated under those conditions, there can be confidence that the risks posed by the genetically modified plant are low. Application of a criterion of increased rigour for hypothesis testing helps to establish whether requests for additional data are justified, and may reduce environmental risk by preventing undue delay in the registration of environmentally beneficial products.

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No Detection of Cry1Ac Protein in Soil After Multiple Years of Transgenic Bt Cotton (Bollgard) Use

Cited by 131 publications

References 21 publications

A review of the environmental safety of the Cry1Ac protein

A review of the environmental safety of the Cry1Ac protein

Decomposition of residues and loss of the δ-endotoxin from transgenic (Bt) corn (Zea mays L.) in soil

Environmental Risk Assessment of Genetically Modified Crops: General Principles and Risks to Non-target Organisms

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