Genetically modified (GM) crops have generated a great deal of controversy. The use of biotechnology in agriculture has caused major ideological and scientific concerns that continue to be echoed in the media and academic press
[1]. Since commercially introduced to farmers in 1996, the global area cultivated with GM crops has increased 94-fold, from 1.7 million hectares to 160 million hectares in 2011
[2]. The rapid adoption of this technology has had substantial socio-economic impacts
[3]. Consequently, a vast amount of technical and non-technical literature addressing this topic has accumulated over the last two decades
[4]. Moreover, groups of stakeholders characteristically advocate opposing opinions, which may not be based on best available evidence. Therefore, the availability of transparent and reliable reviews of studies on the socio-economic impacts of GM crops could help promote evidence-based dialogue among the diverse parties involved. Systematic maps employ structured procedures that can be particularly useful for minimizing potential biases that may arise during the process of identification, selection, and analysis of evidence involved in controversial topics. Systematic maps provide an opportunity to gather and describe evidence relevant to a broad field of policy and management relevancea. The breadth of the evidence captured in a systematic map helps to clearly identify potential research gaps and guide future research efforts
[5]. In addition, systematic maps make relevant evidence readily accessible to researchers and stakeholders through the development of extensive databases, the content of which can be relatively easily updated as needed.
Currently, numerous literature reviews and meta-analysis studies have assessed the socio-economic impacts of GM crops (a non-comprehensive list of 20 studies is included in the Additional file
1). Nevertheless, none is a systematic map, and only one is a systematic review (see Hall et al.
[6])b. That systematic review focused on the costs and profits of GM agriculture in comparison with conventional agriculture. One shortcoming of the document, as stated by the authors, was the exclusion of studies conducted before 2006, which disregards valuable earlier literature. The authors also clarified that
[6]: “Additional time for conducting a systematic review such as this one would allow the inclusion in the search process of additional databases that were excluded because it was not possible to directly export results to Reference Manager Database. An extended review on this topic would be a potentially valuable contribution to the ‘GM debate’”.
Through the EU project “GMO Risk Assessment and Communication of Evidence” (GRACE, 2012–2015), comprehensive reviews of existing evidence of potential health, environmental, and socio-economic impacts of GM crops worldwide will be conducted
[7]. As members of GRACE, the authors of this protocol (Technische Universitaet Muenchen, TUM) will undertake a systematic map on the socio-economic impacts of genetically modified (GM) crops. In particular, the Description of Work (DoW) for GRACE states that TUM is responsible for carrying out reviews on the following key topics: (1) farm-level economic impacts of GM crops; (2) economics of coexistence; (3) economics of segregation at the level of supply-chains; and (4) consumer acceptance of GM crops.c GRACE is following a participatory approach, and stakeholders are being consulted during each of the project’s steps. The stakeholders include members of industry and civil society organizations, as well as competent authorities on GM crops in the EU Member States and scientific experts from academiad. Two new topics were added based on stakeholder requests: environmental economic impactse of GM crops and the impacts of GM crops on food security (for more information about the participatory process, see GRACE
[8]). Therefore, TUM will produce a systematic map covering the six topics stated above, the overall conceptual model of which is outlined in Figure
1. The extensive systematic map will address the broad review question: what are the socio-economic impacts of genetically modified crops worldwide?
The systematic map undertaken will provide an important overview of the existing literature related to the socio-economic impacts of GM crops available in six languages (Chinese, English, French, German, Spanish, and Portuguese). These languages are among the top nine used for publication of researchf
[9] and also the primary languages spoken in 23 of the 28 countries currently cultivating GM crops
[10].
The description of the topics to be covered in the systematic map is provided below.
Farm-level impacts
Farmers have different socio-economic motivations for adopting GM crops. Significant socio-economic determinants include: gender associated aspects (e.g.,
[11]); individual and social learning (e.g.,
[12]); educational level (e.g.,
[13]); and expected benefits and uncertainty (e.g.,
[14–16]). For GM adopters, potential changes in yield and economic returns depend on current and previous crops and specific trait characteristics; agricultural practices; incidence of pest infestation; seed costs; and market characteristics (e.g.,
[17, 18]). Farmers’ production efficiency (farmers’ ability to produce more with less than or equal inputs/resources) would also be affected (e.g.,
[19]), as well as the frequency of pesticide poisoning incidents and health impacts (e.g.,
[20]). Consumption of new bio-fortified GM crops are expected to increase farmers’ nutrition status and as such, they could significantly contribute to farmers’ well-being (e.g.,
[21]). Most of the world’s poor depend mainly on farming for their subsistence. The adoption of GM crops could have different impacts on wealthier and poorer farmers (e.g.,
[22]), which could exacerbate/mitigate social problems. Ethical aspects may also be affected, as it has been demonstrated that ethical values can change over time (e.g., changing views on euthanasia in the U.S. and Japan
[23]). A change in acceptability of GM crops may imply a change in adopters’ values. Finally, cultural aspects may be impacted as well; for example, GM seeds need to be purchased, causing a disturbance in the traditional exchange of seeds among indigenous farmers (along with potential changes in identity and trust among involved farmers).The main aspects considered within this topic are presented graphically in a conceptual model (Figure
2). This conceptual model shows that socio-economic factors influence farmer decisions regarding the adoption of GM crops. GM adoption is expected to impact aspects related to farmers’ income and also intangible aspects. The potential income-related impacts include changes in the use of inputs; associated costs; output (quantity and quality); and gross income. Some farmers could experience changes in time available for conducting off-farm income-generating activities. A farm’s efficiency could deteriorate or improve with use of new technologies impacting the farmer’s income. Intangible aspects that may be affected after GM adoption relate to health safety issues associated with changes in pesticide use and farmers’ nutritional status if they cultivate and consume bio-fortified crops. Primary social, ethical, and cultural aspects are also depicted in the conceptual model.
Coexistence related impacts
The possibility that GM farms contaminate non-GM farms via unintentional or inadvertent gene flow constitutes a challenge for the coexistence of GM farming and conventional agriculture, including organic certified agricultural systems. Several studies have analysed the effects that the introduction of ex-ante regulatory and ex-post liability aspects would have on farm-level costs and GM spatial configuration and adoption dynamics (e.g.,
[24–26]). In addition, potential benefits due to higher price premiums for non-GM products have also been evaluated (e.g.,
[27]).The main aspects considered within this topic are presented graphically in a conceptual model (Figure
3). This conceptual model shows that GM plants and crops can be introduced under alternative coexistence systems (separation between GM and non-GM farms and dual GM/non-GM farms) and regulatory frameworks, including ex-ante (e.g., mandatory segregation, traceability, minimum GM tolerance levels, rigid and flexible refuge areas, and voluntary GM-free zones) and ex-post liability aspects (e.g., compensation funds, insurance schemes, and marketplace liability). The different coexistence options are expected to influence in different manners GM and non-GM farm-level costs, particularly operational; transaction; opportunity; and testing and remediation costs. GM adoption dynamics could change as well, such as the rate of adoption, spatial configuration, and speed and stability of GM expansion. GM-farmers would also generate externalities and directly influence the economic benefits of non-GM farmers due to inadvertent gene flow from GM to non-GM fields which may create problems for non-GM farmers willing to sell their products in specific markets (e.g., organic certified markets). Finally, social factors, such as the level of trust between neighbors, would influence farm-level costs (e.g., lower/higher negotiation costs) and adoption dynamics of GM crops (e.g., stronger/lower imitation or neighboring effects) in each of the ex-ante and ex-post regulatory regimes under evaluation (social aspects not pictured in the figure).
Supply chain impacts
The focus of this section is on the supply chain or organization network as unit of analysis. It aims to analyse the socio-economic impacts of the commercialization of GM crops on supply chain structure and performance dynamics, as well as cost and benefit distribution along different actors in the supply chain.
In general, the basic elements of the structure of the supply chain include:
-
(a)
Vertical relations. These refer to the sequence of value adding activities. Actors performing different functions within the supply chain are vertically linked through buying and selling relationships. Vertical relations highlight the level of cooperation, coordination, trust, and governance (or power) along the chain.
-
(b)
Horizontal relations. These reflect the relationships among actors performing the same function within the chain. Horizontal relations can be formal (e.g., cooperatives and associations) or informal.
The main factors related to supply chain performance are:
-
(a)
Efficiency or the ability to deliver value at a minimum of total costs.
-
(b)
Effectiveness or the ability of the chain to provide superior value.
-
(c)
Innovation or the ability to respond to changes in consumer demand or the external environment.
Several studies have analysed the effect that the commercialization of GM crops would have on the supply chain structure, as well as the distribution of costs and benefits of different actors along the supply chain (e.g.,
[28–32]). Moreover, governance mechanisms and market power of different actors would also be affected (e.g.,
[33, 34]). The main aspects considered under this topic are presented graphically in a conceptual model (Figure
4). This conceptual model shows that the commercialization of GM products under different enforced coexistence rules, labeling schemes, and protection of intellectual property rights would have impacts on the supply chain structure (e.g., vertical and horizontal relations) and performance (e.g., efficiency, effectiveness, and innovation ability). This in turn would affect the distribution of costs and benefits for the different actors along the supply chain, as well as their market power (ability to influence the price of a commercialized item).
Consumer-level impacts
The socio-economic determinants for consumers’ acceptance of GM food and the associated price premiums for non-GM products have been evaluated under different mandatory and voluntary GM-related label schemes (e.g.,
[35–37]). Other studies have evaluated the option values of a moratorium or ban on GM products (e.g.,
[38]). Those price premiums and option values have been used to calculate economic welfare effects (e.g.,
[39]). These and other main aspects related to the impacts of GM products on consumers are presented graphically in a conceptual model (Figure
5). The conceptual model shows that GM products can be introduced into the market under mandatory and voluntary GM-related labels, including different tolerance levels (or percentage of GM ingredients in the final products) or can be subject to moratorium or ban. The decision or intention to buy those products is based on consumers’ socio-economic characteristics (e.g., age, gender, and educational level). Potential buyers can indicate their willingness to pay (WTP) for these products, and changes in social welfare can be calculated based on the differences between the WTP and actual or expected prices (price premiums). If there is a moratorium or ban on GM products, option values can be calculated based on a (hypothetical) WTP to preserve or maintain this situation. Social welfare can be estimated by the difference between the WTP and the opportunity costs of forgoing economic growth associated with the commercialization of GM products. GM products can have an impact on consumers’ health, for example in the case of bio-fortified food. Social, ethical, and cultural aspects were added as requested by stakeholders.
Environmental economic impacts of GM crops
GM crops may substitute for agricultural inputs and practices that are environmentally harmful. The study by Brookes & Barfoot
[40] suggest that “since 1996 the use of pesticides (counted as active ingredients) on the GM crop area was reduced by 448 million kg (9% reduction), and the environmental impact quotient — an indicator measuring the environmental impact associated with herbicide and insecticide use on these crops — fell by 17.9%. In 2010, the total carbon dioxide emission savings associated with GM crop adoption were equal to the removal from the roads of 8.6 million cars due to reduced fuel use and additional soil carbon sequestration”.
GM crops can cause environmental harm as well (although there is considerable uncertainty and no consensus among scientists)
[41]. In particular, the protection of biodiversity and ecosystem services ought to be a top priority when taking into consideration the dependency on a healthy environment of all human activity, now and in the future
[42]. For those opposed to GM technology, GM crops are exotic species being introduced into open complex ecosystems of which we have limited understanding
[43], and as such it is impossible to anticipate all impacts of GM technology on the environment.
The effects of GM crop adoption on the environment will depend not only on human behavior but on biological, ecological, and chemical interactions as well. Many disciplines are needed to evaluate these kinds of impacts
[41]. In addition, there is the possibility of irreversible ecosystem disruptions due in part to the unpredictable and novel effects of gene mixing
[43].
Figure
6 shows a basic conceptual model of the potential environmental economic impacts of GM crops (based on information obtained from
[40–46]). Depending on the type of genetic modification, the cultivation of GM crops can change the type or quantity of herbicide/insecticide used, improve the crops’ resistance to external climate stress (e.g., drought and salinization), or cause an undesired gene flow (e.g., from GM crops to wild relatives).
Changes in the type or quantity of herbicide/insecticide could create or alter herbicide resistance in weeds or pesticide resistance in pests. Soil, water, and air contamination is reduced if the substituted herbicide/pesticide was more toxic than the new herbicide/pesticide. Further, if less herbicide/pesticide is required, resources like fuel could be saved. Changes in herbicide/insecticide use could also modify agricultural practices, such as encourage tillage, weed management, or monoculture. New alternative agricultural practices could change the use of resources and fuel consumption, which in turn would have impacts on soil, water, and air contamination and soil organisms and biodiversity. In addition, there could be improvements in crop yields using existing land and water resources, which in turn could reduce land use; water and air contamination; minimize the impacts on biodiversity; and save resources and fuel consumption. In a similar manner, the cultivation of drought- and salinity-tolerant GM crops would also impact soil, water, air, biodiversity, and modify the use of resources and fuel consumption. Finally, there could be a gene flow from GM crops to wild relatives with unknown consequences to the environment.
It is worth mentioning that this protocol contemplates the environmental economic impacts of GM crops. Therefore, only primary studies incorporating an economic assessment of these and similar environmental impacts will be considered. The environmental impact assessment component of the included primary studies will be taken as given.
Food security at household level
The estimated number of undernourished people has continued to decrease, but the rate of progress still appears insufficient to reach international goals for hunger reduction
[47]. Currently, about 842 million people (one in eight people in the world) suffer chronic hunger, unable to obtain the amount of food necessary to conduct an active life
[47]. The vast majority of hungry people live in developing countries, where the prevalence of undernourishment is estimated at 14 percent
[47].
Food security exists when all people, at all times, have physical and economic access to sufficient, safe, and nutritious food that meets dietary needs and food preferences for an active and healthy life
[47]. There are four dimensions of food security: food availability (e.g., food production and processing); food access (e.g., having the economic resources to buy the right food); food utilization (e.g., education to individuals to make proper use of healthy food); and food system stability (e.g., adequate access to food at all times). For food security objectives to be realised, all four dimensions must be fulfilled simultaneously
[47, 48].
Therefore, food security is a multidimensional concept, and data on all dimensions are rarely available and frequently unreliable
[49]. Moreover, the international community lacks a consensus on core household food security indicators needed in order to properly measure and monitor food security worldwide. The indicators also vary on level of analysis, ranging from the regional or national level to the household or individual level, depending on data availability and the design of the instruments used to collect the data (e.g., surveys)
[49].
In relation to GM crops, reports from expert governmental and nongovernmental bodies increasingly include GM crops as part of a wider approach to food security
[50]. GM crops could help to mitigate expected food shortages related to population growth and the effects of climate change in specific regions worldwide. For example, GM crops could impact food availability by providing seeds which are resistant to adverse climate conditions; have an effect on food access by increasing farmers’ incomes; and, under the same food utilization conditions, bio-fortified crops could increase the nutritional status of households worldwide. (Figure
7 illustrates this example).
In the approach followed in this protocol, the ultimate goal of food security is to improve the nutritional status of households. It is worth mentioning that several of the multidimensional aspects of food security have been already covered by other topics in this protocol (e.g., impacts of GM crops on farm-level income). Nevertheless, there are a growing number of socio-economic studies which specifically evaluate the impacts of GM crops on (at least one component of) food security and explicitly indicate that as so.