Green chemistry in agriculture
GREEN CHEMISTRY IN AGRICULTURE
What Green chemistry actually is? Why it is used in agriculture?
Well its clear defination is:-
Green chemistry, also known as sustainable chemistry, is an umbrella concept that has grown substantially since it fully emerged a decade ago. By definition, green chemistry is the design, development, and implementation of chemical products and processes to reduce or eliminate the use and generation of substances hazardous to human
health and the environment.
So, to make it easy we made a chart or content of our document
GREEN CHEMISTRY AND AGRICULTURE
- Introduction
- Goals and Focus of the project
- Context: Pesticide use overall, biopesticide market growth
- Methodology
- How green chemistry links to sustainable agriculture
- What is involved in replacing a ubiquitous pesticide of concern?
- Biopesticides
- Opportunities and challenges
- Overview
- Discussion
- Conclusion
Introduction
As a society we are receiving clear signals that some chemicals
routinely used in conventional agriculture are associated with alarming
health and environmental effects. From human to ecological health
impacts, there are growing concerns about how we farm. In contrast,
‘Sustainable Agriculture’ describes a robust and balanced agricultural
system to which many increasingly aspire. There are many unknowns in
the details of how such an agricultural system would work, what inputs
would supply it, and what technologies to employ in the transition.
We do know, however, that Green Chemistry innovations will be key to
transitioning to a more sustainable agricultural system.
where we stand on the path towards change – are we close to replacing
some of the most egregious agricultural chemicals or is the technology
gap still wide? What are Green Chemistry’s strengths and what are
its weaknesses in approaching these issues? Are there technologies
available that could benefit from clear demonstration of market
demand? How can we be sure that these new chemicals are safe?
Goals and focus of this project
Advancing Green Chemistry (AGC) set out to “scope” the field of green chemistry and evaluate the capacity of green chemistry to facilitate a shift to sustainable agriculture. We asked the following questions:
• How does green chemistry currently connect with agriculture?
• What are the leading areas of green chemistry innovation that are relevant to
sustainable agriculture?
• What is involved in developing replacements for ubiquitous chemicals of concern
used in agriculture?
• What are the opportunities and obstacles to green chemistry innovations in
agriculture and what are some strategic suggestions for moving them forward?
AGC did a year-long survey of the field of green chemistry to find initial answers to these
questions. What we discovered was that, in short, the sector within green chemistry that
self-identifies as being applicable to sustainable agriculture is very much in the minority.
There have been two significant efforts in the past to connect these fields- in 2003 a book, “Agricultural Applications in Green Chemistry” contained papers from a symposium on the subject; and, in 2007, A CHEMRAWN XII conference “The Role of Chemistry in Sustainable Agriculture and Human Wellbeing in Africa”. Interaction between green chemists and the field of conventional agriculture, however, is trending upward fast, as pressure to develop biofuels and biomaterials is mounting. The missing link in this relationship is that most green chemists developing bio-based materials are not demanding feedstocks that have been sustainably produced. Closing this loop of awareness and interaction is a challenge to place before the field of green chemistry.
Though green chemistry applications for sustainable agriculture are relatively few, there is a specific area within green chemistry that has direct implications for sustainable agriculture: the field of biopesticides. We have chosen to focus this project on biopesticides because the field is the most likely source for alternatives to some of the pesticides of greatest concern. Several Presidential Green Chemistry Challenge Awards have been given for innovations in biopesticides. Also, the area of biopesticides is a) a rapidly growing market, b) raises
both optimism and concerns, and c) is a critical new issue area for anyone concerned with agriculture. A chief conclusion of this study, however, is that as it grows in scale, the field of biopesticides is ripe for green chemistry’s broad, principles-based approach to stainability.
Context: Pesticide use overall, biopesticide market growth
The market for biopesticides is expanding rapidly: growing at some 10% per year, by 2010 global sales are expected to hit the $1 billion mark and make up 4.2% percent of the overall pesticides market. Much of this rapid growth is due to the fact that, perhaps surprisingly, more than 80 % of biopesticides are used, not by organic farmers, but by producers employing conventional farming practices. Orchard crops hold the largest share of total biopesticides use at 55%. It is hard to get current data on overall pesticide use; tracking this data is not in the purview of the USDA, and the EPA last reported on pesticide use data in 2001. Expert estimates, however, hold that overall pesticide use has been declining at a rate of some 1.3% per year over the last decade. This decline is attributed to increased concerns about health and environmental effects, the rise in organic agriculture, and the emergence of alternatives, including biopesticides. In fact, as we shall discuss, the banning of particular pesticides in some cases has been a direct driver of the discovery (and in some cases the rediscovery and development) of biopesticide alternatives.
Methodology
Over the course of a year, Advancing Green Chemistry consulting staff surveyed publicly available literature and information and conducted a series of interviews. Experts consulted included: specialists in green chemistry and sustainable agriculture, environment and health, as well as in biopesticides, ranging from those directly involved in scientific research and product development, to regulation and industry representatives. AGC staff interviewed 23 experts, the list of
which is included at the end of the accompanying manuscript.
How green chemistry links with sustainable chemisty
Green chemistry and sustainable agriculture are both revolutionary fields with significant overlap, though the connections are not fully developed nor appreciated. Sustainable agriculture encompasses a wide variety of farming techniques and practitioners. Broadly speaking sustainable agriculture seeks to achieve three goals: farm profitability; community prosperity; and environmental stewardship. The latter includes: protecting and improving soil quality, reducing dependence on non-renewable resources, such as fuel, synthetic fertilizers and pesticides and minimizing adverse impacts on safety, wildlife, water quality, and other environmental resources.
Both of these fields envision safe products, healthy people, a clean environment, green jobs, and most importantly, a systemic approach to sustainably producing what we need. No one action or technique, taken out of context, provides the answer; but an interconnected system of sustainable technologies and approaches will move us closer to our ultimate goals. Green chemistry and sustainable agriculture are inherently intertwined; farmers need green chemists to make safe agricultural chemical inputs. Green chemists need farmers practicing sustainable agriculture to provide truly “green” bio-based raw materials to process into new products. It is a vital circle of creative interdependence – yet very few practitioners in either field are aware of this fact. There are three ways in which green chemistry connects with sustainable agriculture: as a consumer of agricultural products, as a source for remediation technologies, and as a producer of inputs.
First, green chemistry is a consumer of agricultural inputs: biofeedstocks and
biocatalysis are central to Green Chemistry. In its founding principles green chemistry encourages the use of bio-based materials – specifically, chemists should, whenever possible, use raw materials and feedstocks that are renewable. Renewable feedstocks can come from specifically grown agricultural crops or from agricultural waste products. Green chemists are creating biocatalysts to be employed in the conversion of agricultural materials into high value products, including novel carbohydrates, polysaccharides, enzymes, fuels, and chemicals. Green chemistry’s explicit encouragement of the use of biofeedstocks and biocatalysts provides a direct link to agriculture. What is less explicit, however, in the green chemistry literature is whether biofeedstocks themselves should be produced in a way that is sustainable. One of the goals to emerge from this project is to promote this focus within the Green Chemistry community.
Second, green chemistry intersects with agriculture through applications for site remediation. Traditional farming practices leave unwanted chemicals in the environment—in the soil, water and air. Green Chemists are tackling the challenge of removing pollutants without, in the process, creating more toxic waste. For example, Green Chemists at Carnegie Mellon University have developed TAML® catalysts that can be safely used to remove specific chemicals, including pesticide residues (including atrazine and alachlor), from water. Such GC innovations should not be viewed as a panacea for continued use of these chemicals, but they give communities a valuable tool with which to deal with contamination and to help farmers deal with the transition to more organic methods, and to more generally manage the use of recycled water.
Third, and the focus of this paper: green chemistry is necessary to generate greener inputs for agricultural production. Green chemistry alternatives are vital to sustainably producing agricultural goods without continued dependence on toxic pesticides and chemicals of concern. One central question of the health and environmental communities is how close are we to replacing pesticides/chemicals of concern with greener alternatives? Promising work is underway in green chemistry; new pesticides are being designed and produced that can be more benign and/or more targeted. Biopesticides - derived from plant or microbial “pesticides” - is an area in which there is a lot of movement and potential for Green Chemistry to supplant certain chemicals of concern, and is where we chose to focus this study.
What is involved in replacing a ubiquitious chemical of concern?
We discovered no “Manhattan project” underway to replace some of the most ubiquitous and suspect chemical pesticides in agricultural use (though indeed such efforts might be happening undercover). Moreover, it is unlikely that green chemists will discover a single brilliant “green” solution to replace a dangerous ubiquitous chemical. The logic of this is simple: a “green” broad-spectrum pesticide that kills everything it comes into contact with is extremely hazardous (it still kills everything - targets and non-targets). The more narrowly one defines the focus of a pesticide, such that its target is more refined, the more of a specialized niche product it is.
This is indeed what we found: the various services of broad-spectrum pesticides are being addressed and replacements created on a by-use basis. For example- it is very unlikely that there will be one over arching “green” replacement for methyl bromide; rather there will be a variety of replacements developed– one greener alternative to address pests particular to strawberries, another for tomato pests. As safer replacements tend to be more specifically targeted, the market for them is consequently narrower. Small or niche markets sometimes mean that green chemistry solutions are left sitting on the shelf because the costs of manufacturing is too high and demand for a solution is too low.
Biopesticides
In very general terms, according to the US EPA, biopesticides are pesticides derived from natural materials such as animals, plants, bacteria, and minerals. The two key categories focused on in this report include biochemical and microbial pesticides (reviewing the third category of biopesticides, transgenic crops, was outside the scope of this report). The subcategories of biochemical pesticides introduced in this report include insect pheromones, plant extracts and oils, plant growth regulators and insect growth regulators. Microbial pesticide subcategories discussed include bacteria, virus, fungus, and other less common microorganisms.
Some common benefits and disadvantages of biopesticides in comparison with conventional pesticides are shown in the table below. While this table presents generalities, each category of biopesticide and each individual product must be analyzed individually to assess the full range of impacts and trade-offs of the particular product on human and environmental health endpoints as well other factors related to grower adoption.
Table 1(on progress)
Opportunities and challenges
The field of biopesticides is deep, consequently they are a source of both optimism and concern. There is a tremendous amount of work and research occurring in this field, but like other green chemistry solutions, developing safe, effective biopesticide products requires holistic thinking and multi-disciplinary approaches to establishing safety, which is a challenge for the biopesticide industry. Turning lab discoveries into profitable business products is also daunting. This mirrors what other inventors face when implementing green chemistry solutions in other sectors. Also, it is important to note that biopesticides fall along a spectrum of toxicity. At one end are products that are extremely narrow in focus (e.g. targeting a single species in a specific window of its life cycle). At the opposite end are biopesticide products that are wider in effect (pyrethroids for example, derived from chrysanthemums, affect a relatively wide range of species and can have unintended toxic collateral effects). When highly specified, biopesticides can be almost utterly benign in their human and environmental effects. When their impact is broader, however, biopesticides raise some of the same human and ecosystem impact concerns that conventional pesticides do. Table 1 sums up key pros and cons that result from this investigation into biopesticides.
Overview: General Pros and Cons of Biopesticide Active Ingredients in Comparison with Conventional Pesticides
Generally speaking, there are distinct benefits to using biopesticides in comparison with conventional chemical pesticides. These advantages also bring with them their own uniquem disadvantages as can be seen in Table 1. In sum, biopesticides tend to be less toxic, more quickly biodegradable, and more targeted to the specific pest (US EPA Pesticides, 2008). With a narrower target range of pests, they also tend to have a more specific mode of action (Clemson HGIC, 2007). Biopesticides are often designed to control a pest population to a manageable level rather than completely eradicate a target pest (Lewis and others, 1997). These technical differences translate into benefits to humans and ecosystems including increased food safety, worker safety, and reduced concerns for development of pest resistance to existing control tools.
There are also some general challenges with use of biopesticides. They tend to be more slow-acting (Clemson HGIC, 2007) and may be very specific to the life cycle of the pest. Other attributes such as persistence in the environment have both a benefit and challenge that must be balanced. For example, a biopesticide that degrades very quickly in the environment (benefit) may also have a short shelf life or limited field persistence (Clemson HGIC, 2007) requiring multiple applications. Having a narrow target range and very specific mode of action can be seen as both a benefit and a challenge (Clemson HGIC, 2007). While one benefit of specificity is lower impact on non-target species, one challenge is that control of the dominant pests on a given crop may require more than one product and may be more costly. Also as noted, biopesticides fall on a continuum of breadth of specificity: some active ingredients are highly specific to a particular organism at a particular window of opportunity; others have a broader mode of action.
Discussion: Opportunities and Challenges of Biopesticides
Biopesticides, generally speaking, are targeted and can be non-toxic.
Some attributes of biopesticides can be seen as both benefits and disadvantages. For example, the specificity of many biopesticides minimizes the negative impact on non-target organisms because they are designed to target a specific pest. The benefits of this can be profound: by focusing on an individual pest, biopesticides are generally much less toxic than conventional pesticides. However, as noted above, some biopesticide products are broader spectrum actors and consequently can have negative impacts on non-target species. These broader systemic impacts could be better understood – and anticipated – if the right questions are asked.
Broader questions of hazard are sometimes poorly understood.
Many chemistry research institutions do not investigate chemicals for hazard in its broadest sense. This is true in both the agricultural and industrial chemical sectors. For example, the USDA has several research labs across the United States that focus on discovering new products, pesticides and more, sourced from nature. The typical process is: the USDA does the basic research and, when promising chemicals are identified, USDA licenses them to universities or industry for further research into the applications of the chemical. But USDA
does not investigate whether or not the chemicals they license are hazardous to human health and the environment. There are missing skills sets in the product discovery and development process. Broader questions of human and ecological health – both for the active ingredient and the inert ingredients in which the active ingredient is suspended – often are not systematically addressed.
Banning bad actor chemicals is a powerful driver
Forcing toxic chemicals out of the marketplace provides incentives for developing green chemistry solutions and makes these solutions commercially viable. As a result several new biopesticide technologies for managing pests formally treated with these more toxic pesticides have come to market. Without the bans, the research funding for alternatives and the market space for new products would not have been allocated. For example, the severe restriction of Azinphos-methyl and the ban on methyl parathion made it essential to develop safer alternatives for controlling the Codling Moth.
Biopesticides offer growers both opportunities – and challenges.
Biopesticide solutions often require the grower to learn new application techniques and new ways of thinking about pest management. As noted, biopesticides are often highly specific and have very precise modes of action. This specificity can mean that workers can enter fields quickly after use, thus cutting wait times and offering more flexibility to the user. Specificity also means, however, that growers may need to purchase several different kinds of
product to meet their pest management needs; this is a potential cost concern for growers. Biopesticides also require new skills and understanding of pests, their life cycles and how to use biopesticides to intercede effectively. This is both a challenge but also an opportunity for expanding a new category of skilled labor in the farm sector.
Efficacy is Key
Green chemistry solutions must work. Proving efficacy in comparison to traditional pesticides is one of the chief concerns of the biopesticide industry. The Biopesticide Industry Alliance is beginning to define industry standards. To date, these standards have focused on efficacy. There is an opportunity, however, to encourage this industry to develop standards that reflect
green chemistry principles – including inherent human and ecological hazard.
Transparency and Dialogue are Essential
Transparency is essential to public adoption of all green chemistry solutions, including biopesticide products. Negative public reactions to biopesticides have been due to a lack of transparency about inert ingredients used in a product, as well as to negative side effects of some broader spectrum biopesticides on non-target species. These issues can be prevented if products are developed using a green chemistry principles-based approach and if more inclusive public dialogue were employed about these products.
Conclusion
Biopesticides are a set of tools and applications that will help our farmers transition away from highly toxic conventional chemical pesticides into an era of truly sustainable agriculture. Of course biopesticides are only a part of a larger solution; sustainable agriculture is a broad and deep field. But helping farmers move from their current chemical dependency to organic agriculture and beyond requires tools for the transition and tools for a new era. Biopesticides
can and will play a significant role in this process.
There remain, however, serious questions about the safety of these products from both a human and ecosystem health standpoint. Current regulations do not go nearly far enough in evaluating systemic broader impacts of biopesticides. By definition, green chemistry is about continuous improvements aimed at reducing or eliminating hazard. Fully defining hazard is difficult. Even products hailed by green chemistry and regulators alike as safer for human health may turn out to have unforeseen negative environmental health impacts- for example, Spinosad, a green chemistry award winning biopesticide, is significantly safer for humans than other treatments but is toxic to bees.
We must encourage pest management solutions and regulations to continuously evolve and ensure that multi-disciplinary teams, including green chemists, environmental health sciences and other sciences, approach these products systemically to both discover and refine them.
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