title: Genetically modified crops and aquatic ecosystems: considerations for environmental risk assessment and non-target organism testing.
abstract: Environmental risk assessments (ERA) support regulatory decisions for the commercial cultivation of genetically modified (GM) crops. The ERA for terrestrial agroecosystems is well-developed, whereas guidance for ERA of GM crops in aquatic ecosystems is not as well-defined. The purpose of this document is to demonstrate how comprehensive problem formulation can be used to develop a conceptual model and to identify potential exposure pathways, using Bacillus thuringiensis (Bt) maize as a case study. Within problem formulation, the insecticidal trait, the crop, the receiving environment, and protection goals were characterized, and a conceptual model was developed to identify routes through which aquatic organisms may be exposed to insecticidal proteins in maize tissue. Following a tiered approach for exposure assessment, worst-case exposures were estimated using standardized models, and factors mitigating exposure were described. Based on exposure estimates, shredders were identified as the functional group most likely to be exposed to insecticidal proteins. However, even using worst-case assumptions, the exposure of shredders to Bt maize was low and studies supporting the current risk assessments were deemed adequate. Determining if early tier toxicity studies are necessary to inform the risk assessment for a specific GM crop should be done on a case by case basis, and should be guided by thorough problem formulation and exposure assessment. The processes used to develop the Bt maize case study are intended to serve as a model for performing risk assessments on future traits and crops.
authors: Regulatory Science, Pioneer Hi-Bred, DuPont Agricultural Biotechnology, 2450 SE Oak Tree Ct., Ankeny, IA 50021, USA. keri.carstens@pioneer.com
authors: Keri
authors: K
authors: Carstens
authors: Jennifer
authors: J
authors: Anderson
authors: Pamela
authors: P
authors: Bachman
authors: Adinda
authors: A
authors: De Schrijver
authors: Galen
authors: G
authors: Dively
authors: Brian
authors: B
authors: Federici
authors: Mick
authors: M
authors: Hamer
authors: Marco
authors: M
authors: Gielkens
authors: Peter
authors: P
authors: Jensen
authors: William
authors: W
authors: Lamp
authors: Stefan
authors: S
authors: Rauschen
authors: Geoff
authors: G
authors: Ridley
authors: Jörg
authors: J
authors: Romeis
authors: Annabel
authors: A
authors: Waggoner
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics; D002080:Butterflies / Q000254:growth & development / Q000502:physiology; D004777:Environment; D006801:Humans; D056127:Hydrobiology; D030821:Plants, Genetically Modified / Q000009:adverse effects*; D012107:Research Design; D018570:Risk Assessment; D003313:Zea mays / Q000235:genetics