ABSTRACT
Background: Antimicrobials revolutionized human as well as animal medicine in the 20th century by providing effective treatment of diseases caused by pathogenic microorganisms. However, microorganisms have the ability to develop antimicrobial resistant strains. This occurs when microorganisms mutate or when resistance genes are exchanged between them. The use of antimicrobial drugs accelerates the emergence of drug-resistant strains. A priority is to safeguard the efficacy of antimicrobial drugs we depend on for treatment of infectious diseases in humans. Use of antimicrobials in food animals can create a source of antimicrobial resistant bacteria that can spread to humans both by direct contact and through the food supply. Coccidiosis is an intestinal disease in animals caused by unicellular parasites called coccidia. As most of the damage of this infection is done by the time signs of the disease are widespread, preventive measures are preferred. Coccidiostats are animal feed additives used to prevent coccidiosis by inhibiting or killing coccidia. There are two major groups of coccidiostats; ionophores and non-ionophores, the latter also referred to as “non-ionophore coccidiostats” (but also called chemicals). One main difference between these groups is that ionophores also inhibit or kill some bacterial species, whereas non-ionophore coccidiostats do not. Consequently, some bacterial infections may also be controlled by ionophore coccidiostats, e.g. the poultry disease necrotic enteritis caused by the bacterium Clostridium perfringens (C. perfringens). Eleven different coccidiostats have been authorised for use in the EU, both ionophores and non-ionophore coccidiostats. Norway has been exempted from the EEA Agreement in this field and has approved only five; all ionophores. The two ionophore coccidiostats currently used in Norway are narasin for broilers and monensin for turkeys. Resistance to coccidiostats in coccidia and bacteria: Development of resistance in coccidia to all eleven coccidiostats has been described in the scientific literature, but the prevalence of resistance is unknown. Cross-resistance between various ionophore coccidiostats has also been shown, i.e. development of resistance to one ionophore may also render the coccidia resistant to another ionophore. Various rotation and shuttle programmes with exchange between ionophores and non-ionophore coccidiostats are believed to prevent or delay development of resistance in coccidia. In Norway, such programmes will have little effect as long as only ionophores and not non-ionophore coccidiostats are approved for use. Development of resistance against ionophores has also been observed in bacteria. In the Norwegian surveillance programme NORM-VET during the years 2002 - 2013, between 50 - 80% of the tested flocks had narasin resistant faecal enterococci, which are bacteria that are part of the normal intestinal microbiota. However, the pathogenic bacterium C. perfringens has not been shown to be resistant against any ionophore. Cross-resistance in bacteria to more than one ionophore has been observed. In addition, a limited amount of data may indicate an association between narasin and resistance to the antibacterials bacitracin and vancomycin. As these are antibacterials used for treatment in humans, more research should be performed to validate these results. Non-ionophore coccidiostats, which do not have antibacterial effect, are not approved in Norway. If such coccidiostats were approved in Norway, coccidiostats with negligible probability of inducing resistance in bacteria would be available. Human exposure to resistant bacteria and coccidiostats: Humans may theoretically be exposed to coccidiostat resistant bacteria from poultry in a number of ways, e.g. by handling live animals and their manure, through slaughtering and processing, and by preparation and consumption of poultry meat. Furthermore, bacteria of the human normal microbiota, which cover all skin and mucosal surfaces, might develop resistance if they are exposed to coccidiostats. In this assessment, the probabilities of exposure are classified as: Negligible (extremely low), Low (possible, but not likely), Medium (likely), High (almost certain) and Not assessable. The Panel has estimated the following probabilities of human exposure: Handling manure from coccidiostat fed poultry without sufficient risk-reducing measures entails a high probability of exposure to both resistant bacteria and coccidiostats. Without proper protection, the probability of exposure to coccidiostats is also high when handling coccidiostat premixes and feeds containing coccidiostats without proper protection measures. Various treatments, e.g. composting, of the manure may reduce the probability. The probability of exposure to resistant bacteria is medium for workers handling carcasses and raw meat on a daily basis if risk-reducing measures are not applied, whereas the probability of exposure to coccidiostats is negligible. For consumers, the probability of exposure to coccidiostats is negligible. The probability for exposure to resistant bacteria is also negligible in heat treated food since heat treatment kills the bacteria. The probability of exposure to coccidiostat resistant bacteria is low to medium if handling raw meat without proper hygienic procedures, because raw meat may harbour resistant bacteria. Risk-reducing measures will lower the probabilities. However, little is known concerning the consequences of human exposure to coccidiostat resistant bacteria or to to coccidiostats. There is little information in scientific literature indicating whether such bacteria in fact will colonize the human body, either transitionally or permanently. Furthermore, there is no information on the probability of exchange of resistance genes from transferred bacteria to bacteria of the human natural microbiota or to pathogens. Likewise, the Panel has no information on the level of exposure, e.g. the amount of coccidiostats and their metabolites, or the time period, necessary for the various bacteria to give rise to resistant variants. As coccidiostats are not used to treat infectious diseases in humans, concern of resistance is related to possible cross- or co-resistance with antibacterials considered important in human medicine. Such resistance has so far not been confirmed. Use of therapeutic antibacterials for poultry: If the ionophore coccidiostats used in Norway are replaced by one or more non-ionophore coccidiostat with no antibacterial effect and no other changes are done, the coccidiostats used will no longer inhibit the bacterium Clostridium perfringens, which is the cause of necrotic enteritis. Over time this will likely to lead to a need for intermittent or continuous use of higher levels of therapeutic antibacterials due to increased incidence of this desease in poultry production. The magnitude of the increase is difficult to predict. Alternatives to in-feed antimicrobials: Eradication from the birds’ environment of coccidia causing coccidiosis is difficult to achieve because the coccidia form oocysts that survive outside the host and resist commonly used disinfectants. Vaccination with non-pathogenic vaccines is now used increasingly in commercial Norwegian broiler farms, instead of in-feed coccidiostats. So far coccidiosis has not been reported as a problem in this transition process to broiler rearing without in-feed coccidiostats in Norway. Non-antimicrobial feed additives with purported health-promoting benefits, i.e. acid-based products, probiotics, prebiotics, synbiotics, yeast-based products, plant-derived products, combinations of these, and other products have been developed and used in feed. These products have been tested for efficacy against coccidia with conflicting, non-consistent or non-convincing results. The majority of these products appear to target the bacterial microbiota rather than coccidia. The Panel has not assessed possible effects of other types of management changes.
ABSTRACT
The Norwegian Environment Agency (NEA) and the Norwegian Food Safety Authority (NFSA) requested the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) for an opinion of potential risks to biodiversity and agriculture in Norway associated with import of seeds for sowing and cultivation of insect-resistant and herbicide tolerant genetically modified maize Bt11 under Directive 2001/18/EC (Notification C/F/96.05.10). The notification is still pending for authorisation in the European Union. VKM is also requested to assess the applicant´s post-market environmental monitoring plan, and the management measures suggested in the draft implementing decision of the European Commission. As the scope of the notification does not cover food and feed uses of maize Bt11, VKM was not asked for a health risk assessment of maize Bt11. However, VKM has decided to update a previous safety evaluation of the food and feed uses of maize Bt11 and derived products (VKM, 2014). VKM appointed a working group consisting of members from the Panel on Genetically Modified Organisms, the Panel on Alien Organisms and trade in Endangered Species (CITES) and the VKM staff to answer the requests. The Panel on Genetically Modified Organisms assessed and approved the final report. The genetically modified maize Bt11 was developed to provide protection against certain lepidopteran target pests, such as the European corn borer (ECB, Ostrinia nubilalis), and some species belonging to the genus Sesamia . The insect resistence is achieved by the expression of a truncated form of a Cry1Ab protein encoded by a modified cry1Ab gene derived from the soil microorganism Bacillus thuringiensis subsp kurstaki HD-1. Maize Bt11 also expresses the phosphinothricin - N - ace tyltransferase (pat) gene, derived from the soil microorganism Streptomyces viridochromogenes strain Tu494, which encodes the enzyme: phosphinothricin acetyl transferase (PAT). PAT protein confers tolerance to the herbicidal active substance glufosinate-ammonium. The PAT protein expressed in Bt11 was used as a selectable marker to facilitate the selection process of transformed plant cells and is not intended for weed management purposes. Since the scope of the notification C/F/96.05.10 does not cover the use of glufosinate-ammonium-containing herbicides on maize Bt11, potential effects due to the use of such herbicides on maize Bt11 are not considered by VKM. In delivering its scientific opinion, VKM considered relevant peer-reviewed scientific publications and information provided by the applicant in the notification C/F/96.05.10, the renewal application EFSA/GMO/RX/Bt11, and scientific opinions and comments from EFSA and other EU-member states. VKM has evaluated maize Bt11 with reference to its intended uses in the European Economic Area (EEA), and according to the principles described in the Norwegian Food Act, the Norwegian Gene Technology Act and regulations relating to impact assessment pursuant to the Gene Technology Act, Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms, and Regulation (EC) No 1829/2003 on genetically modified food and feed. The Norwegian Scientific Committee for Food Safety has also decided to take account of the appropriate principles described in the EFSA guidelines for the risk assessment of GM plants and derived food and feed (EFSA 2011a), the environmental risk assessment of GM plants (EFSA 2010a), selection of comparators for the risk assessment of GM plants (EFSA, 2011b) and for the post-market environmental monitoring of GM plants (EFSA, 2011c). The scientific risk assessment of maize Bt11 includes molecular characterisation of the inserted DNA and expression of novel proteins, comparative assessment of agronomic and phenotypic characteristics, nutritional assessments, toxicology and allergenicity. An evaluation of unintended effects on plant fitness, potential for gene transfer, interactions between the GM plant and target and non-target organisms, effects on biogeochemical processes, the post-market environmental monitoring plan and coexistence measures at the farm level has also been undertaken. It is emphasised that the VKM mandate does not include assessments of contribution to sustainable development, societal utility and ethical considerations, according to the Norwegian Gene Technology Act and Regulations relating to impact assessment pursuant to the Gene Technology Act. These considerations are therefore not part of the risk assessment provided by the VKM. Molecular Characterization: Appropriate analyses of the integration site, inserted DNA sequence, flanking regions, and bioinformatics have been performed. The molecular characterisation reported by the applicant shows that the DNA-fragment containing the cry1Ab and pat genes, is integrated as a single copy at a single locus in the nuclear genome of maize Bt11 and that it is stably inherited as a dominant trait. VKM considers the molecular characterisation of maize Bt11 satisfactory. Comparative Assessment: Comparative analyses of data from field trials located at representative sites and environments in North America and Europe indicates that maize Bt11 is compositionally equivalent to its conventional counterpart, with the exception of the herbicide tolerance and insect resistance traits, conferred by the expression of the PAT and Cry1Ab proteins. However, data on the amino acid tryptophan, is only given in one out of six studies. Based on current knowledge, VKM concludes that maize Bt11 is compositionally equivalent to conventional maize. The data provided by the applicant are not sufficient to show that Bt11 maize is phenotypically and agronomically equivalent to conventional near-isogenic maize lines. The agronomic assessment data are provided from one growing season in the North America and one growing season in France. This is not considered to be sufficient for representative testing of agricultural environments. Food and Feed Risk Assessment: Whole food feeding studies have not indicated any adverse health effects of maize Bt11. These studies further support that maize Bt11 is nutritionally equivalent to conventional maize. The Cry1Ab and PAT proteins do not show sequence resemblance to other known toxins or IgE allergens, nor have they been reported to cause IgE mediated allergic reactions. Some studies have however indicated a potential role of Cry-proteins as adjuvants in allergic reactions. Based on current knowledge, the VKM concludes that maize Bt11 is nutritionally equivalent to conventional maize varieties. It is unlikely that the Cry1Ab and PAT proteins will introduce a toxic or allergenic potential in food or feed based on maize Bt11 compared to conventional maize. Environmental Risk Assessment: Maize is the only representative of the genus Zea in Europe, and there are no cross-compatible wild or weedy relatives outside cultivated maize with which maize can hybridise and form backcross progeny. Vertical gene transfer in maize therefore depends on cross-pollination with other conventional or organic maize varieties. In addition, unintended admixture of genetically modified material in seeds represents a possible way for gene flow between different crop cultivations. The risk of pollen flow from maize volunteers is negligible under Norwegian growing conditions. Since maize Bt11 has no altered agronomic and phenotypic characteristics, except for the specific target insect resistance and herbicide tolerance, the likelihood of unintended environmental effects as a consequence of spread of genes from maize Bt11 is considered to be extremely low. There are no reports of the target lepidopteran species attaining pest status on maize in Norway. Since there are no Bt-based insecticides approved for use in Norway, and lepidopteran pests have not been registered in maize, issues related to resistance evolution in target pests are not relevant at present for Norwegian agriculture. Published scientific studies showed that the likelihood of negative effects of Cry1Ab protein on non-target arthropods that live on or in the vicinity of maize plants is low. In Norway, the maize cultivation is marginal. The total crop area of forage maize is estimated to 2000-2800 decares, equivalent to less than 0.1% of the areas with cereal crops. The area of individual fields is limited by the topography such that the quantity of maize pollen produced under flowering is also limited. The potential exposure of Cry1Ab-containing maize pollen on non-target lepidopteran species in Norway is therefore negligible. Cultivation of maize Bt11 is not considered to represent a threat to the prevalence of red-listed species in Norway. Exposure of nontarget organisms to Cry proteins in aquatic ecosystems is likely to be very low, and potential exposure of Cry proteins to non-target organisms in aquatic ecosystems in Norway is considered to be negligible. VKM concludes that, although the data on the fate of the Cry1Ab protein and its potential interactions in soil are limited, the relevant scientific publications analysing the Cry1Ab protein, together with the relatively broad knowledge about the environmental fate of other Cry1 proteins, do not indicate significant direct effects on the soil environment. Despite limited number of studies, most studies conclude that effects on soil microorganisms and microbial communities are transient and minor compared to effects caused by agronomic and environmental factors. However, data are only available from short-term experiments and predictions of potential long-term effects are difficult to deduce. Coexistence: VKM concludes that separation distances of 200 meters most likely will ensure coexistence between genetically modified maize and conventional and organic maize varieties in Norway. Overall Conclusion: Based on current knowledge, VKM concludes that maize Bt11 is nutritionally equivalent t
ABSTRACT
The Norwegian Environment Agency (NEA) and the Norwegian Food Safety Authority (NFSA) requested the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) for an opinion of potential risks to biodiversity and agriculture in Norway associated with import of seeds for sowing, and cultivation of insect-resistant and herbicide-tolerant genetically modified maize 1507 under Directive 2001/18/EC (Notification C/ES/01/01). The notification is still pending for authorisation in the European Union. VKM is also requested to assess the applicant´s post-market environmental monitoring plan, and the management measures suggested in the draft implementing decision of the European Commission. As VKM delivered a scientific opinion on this application including cultivation in 2014 (VKM, 2014), VKM is asked to assess whether the previous risk assessment is still valid concerning cultivation, and to update the opinion after current knowledge. The assessment shall specifically consider Norwegian conditions. Furthermore, as the notification does not cover food and feed uses of maize 1507, VKM was not asked for a health risk assessment of maize 1507. However, VKM has decided to update the previous safety evaluation of the food and feed uses of maize 1507 and derived products from 2014. VKM appointed a working group consisting of members from the Panel on Genetically Modified Organisms, the Panel on Alien Organisms and trade in Endangered Species (CITES) and the VKM staff to answer the requests. The Panel on Genetically Modified Organisms has assessed and approved the final report. The genetically modified maize 1507 was developed to provide protection against certain lepidopteran target pests, such as the European corn borer (ECB, Ostrinia nubilalis), and some species belonging to the genus Sesamia. The insect resistence is achieved by the expression of a synthetic version of the truncated c ry1F gene derived from Bacillus thuringiensis subsp. aizawai, a common soil bacterium. Maize 1507 also expresses the phosphinothricin - N - acetyltransferase (pat) gene, derived from the soil bacterium Streptomyces viridochromogenes. PAT protein confers tolerance to the herbicidal active substance glufosinate-ammonium. The PAT protein expressed in maize 1507 was used as a selectable marker to facilitate the selection process of transformed plant cells and is not intended for weed management purposes. Since the scope of the notification C/ES/01/01 does not cover the use of glufosinate-ammonium-containing herbicides on maize 1507, potential effects due to the use of such herbicides on maize 1507 are not considered by VKM. In delivering its scientific opinion, VKM considered relevant peer-reviewed scientific publications and information provided by the applicant in the notifications C/ES/01/01, C/NL/00/10, the applications EFSA/GMO/NL/2004/02 and EFSA/GMO/RX/1507, and scientific opinions and comments from EFSA and other EU member states. VKM has evaluated maize 1507 with reference to its intended uses in the European Economic Area (EEA), and according to the principles described in the Norwegian Food Act, the Norwegian Gene Technology Act and regulations relating to impact assessment pursuant to the Gene Technology Act, Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms, and Regulation (EC) No 1829/2003 on genetically modified food and feed. VKM has also decided to take into account, the appropriate principles described in the EFSA guidelines for the risk assessment of GM plants and derived food and feed (EFSA, 2011a), the environmental risk assessment of GM plants (EFSA, 2010a), selection of comparators for the risk assessment of GM plants (EFSA, 2011b) and for the post-market environmental monitoring of GM plants (EFSA, 2011c). The scientific opinion of maize 1507 include molecular characterisation of the inserted DNA and expression of novel proteins, comparative assessment of agronomic and phenotypic characteristics, nutritional assessments, toxicology and allergenicity. An evaluation of unintended effects on plant fitness, potential for gene transfer, interactions between the GM plant and target and non-target organisms, effects on biogeochemical processes, the postmarket environmental monitoring plan and coexistence measures at the farm level has also been undertaken. It is emphasised that VKM’s mandate does not include assessments of contribution to sustainable development, societal utility and ethical considerations, according to the Norwegian Gene Technology Act and Regulations relating to impact assessment pursuant to the Gene Technology Act. These considerations are therefore not part of the risk assessment provided by VKM. Molecular Characterization: Appropriate analyses of the transgenic DNA insert, its integration site, number of inserts and flanking sequences in the maize genome, have been performed. The results show that one copy only of the insert is present in maize 1507. Homology searches with databases of known toxins and allergens have not indicated any potential production of harmful proteins or polypeptides caused by the genetic modification in maize 1507. Southern blot analyses and segregation studies show that the introduced genes cry1F and pat are stably inherited and expressed over several generations along with the phenotypic characteristics of maize 1507. VKM considers the molecular characterisation of maize 1507 satisfactory. Comparative Assessment: Comparative analyses of maize 1507 to its non-GM conventional counterpart have been performed during multiple field trials located at representative sites and environments in Chile (1998/99), USA (1999) and in Europe (1999, 2000 and 2002). With the exception of small intermittent variations, no biologically significant differences were found between maize 1507 and the conventional maize. Based on the assessment of available data, VKM concludes that maize 1507 is compositionally, agronomically and phenotypically equivalent to its conventional counterpart, except for the introduced characteristics, and that its composition fell within the normal ranges of variation observed among non-GM varieties. The field evaluations support a conclusion of no phenotypic changes indicative of increased plant weed/pest potential of 1507 compared to conventional maize. Food and Feed Safety Assessment: Whole food feeding studies on rats, broilers, pullets, pigs and cattle have not indicated any adverse health effects of maize 1507. These studies further indicate that maize 1507 is nutritionally equivalent to conventional maize. The PAT and Cry1F proteins do not show sequence resemblance to other known toxins or IgE allergens, nor have they been reported to cause IgE mediated allergic reactions. Some studies have however, indicated a potential role of Cry-proteins as adjuvants in allergic reactions. Based on current knowledge, VKM concludes that maize 1507 is nutritionally equivalent to conventional maize varieties. It is unlikely that the PAT and Cry1F proteins will introduce a toxic or allergenic potential in food or feed based on maize 1507 compared to conventional maize. Environmental Risk Assessment: Maize is the only representative of the genus Zea in Europe, and there are no cross-compatible wild or weedy relatives outside cultivated maize with which maize can hybridise and form backcross progeny. Vertical gene transfer in maize therefore depends on cross-pollination with other conventional or organic maize varieties. In addition, unintended admixture of genetically modified material in seeds represents a possible way for gene flow between different crop cultivations. The risk of pollen flow from maize volunteers is negligible under Norwegian growing conditions. Since maize 1507 has no altered agronomic and phenotypic characteristics, except for the specific target insect resistance and herbicide tolerance, the likelihood of unintended environmental effects as a consequence of spread of genes from maize 1507 is considered to be extremely low. There are no reports of the target lepidopteran species attaining pest status on maize in Norway. Since there are no Bt-based insecticides approved for use in Norway, and lepidopteran pests have not been registered in maize, issues related to resistance evolution in target pests are not relevant at present for Norwegian agriculture. There are a limited number of published scientific studies on environmental effects of Cry1F protein. Published scientific studies show that the likelihood of negative effects of Cry1F protein on non-target arthropods that live on or in the vicinity of maize plants is low. In Norway, the maize cultivation is marginal. The total crop area of forage maize is estimated to 2000-2800 decares, equivalent to less than 0.1 % of the areas with cereal crops. The area of individual fields is limited by the topography such that the quantity of maize pollen produced under flowering is also limited. The potential exposure of Cry1F-containing maize pollen on non-target lepidopteran species in Norway is therefore negligible. Cultivation of maize 1507 is not considered to represent a threat to the prevalence of red-listed species in Norway. Exposure of non-target organisms to Cry proteins in aquatic ecosystems is likely to be very low, and potential exposure of Cry proteins to non-target organisms in aquatic ecosystems in Norway is considered to be negligible. VKM concludes that, although the data on the fate of the Cry1F protein and its potential interactions in soil are limited, the relevant scientific publications analysing the Cry1F protein, together with the relatively broad knowledge about the environmental fate of other Cry1 proteins, do not indicate significant direct effects on the soil environment. Despite limited number of studies, most studies conclude that effects on soil microorganisms and microbial communities are transient and minor c