1 Testing the Unintended Consequences of Lignin Reduction in Genetically Modified Trees on Trophic Interactions Massachusetts Institute of Technology Department of Civil and Environmental Engineering December 1st, 20092 Executive Summary: Genetically modified trees with reduced lignin composition have been proposed as a geoengineering scheme that could potentially reduce environmental impact from chemically harsh pulping practices within the paper industry. Lignin is the complex chemical compound that gives trees their protection against climate, disease, and animal activity. However, the presence of lignin in wood demands the use of toxic chemicals in pulping and paper mills, which constitute sa health hazard to mill workers as well as the natural environment. Decreasing the amounts of lignin in trees raised specifically for the paper industry should result in increased productivity in paper-making and lessen the need for harsh chemicals. Although lignin reduction is a potential method to maximize efficiency and minimize the environmental footprint of the paper industry, it may have unintended consequences upon the environment. Potential side effects associated with lignin reduction include decreased fitness of the transformed trees, transgene escape, and changes in herbivorous insect populations. These are significant because they may endanger the wellbeing of other species and the entire ecosystem. The proposed experiment calls for a long-term field trial that will study and quantify the effect of lignin reduction on trophic interactions in the surrounding environment. Specifically, the field trial will genetically transform Populus tremuloides, or trembling aspen, a species that is commonly used for papermaking, and observe the populations of associated insect herbivores and non-herbivores. The anticipated results of this field trial are that there will be little to no effect on trophic interactions. Although the experiment will not capture the impact of lignin reduction on an entire ecosystem, the results of the field trial should deepen our understanding of how the effects of such a genetic modification permeate through different trophic levels.3 Lignin and Toxic Pulping Waste Ever since the Chinese developed the first papermaking process in the 2nd century CE, paper has been one of the largest and most widespread commodities across the globe. The eventual mechanized production of paper through the printing press in the early 19th century drove up the demand for newsprint and books since paper became relatively cheap and easy to produce. The increase in international demand for paper has consequently led to the chemical pollution of aquatic environments by paper mills as well as deforestation. Before wood is made into paper, it undergoes the pulping process. The breakdown of lignin, the complex chemical compound that gives trees their protection against climate, pathogens, and other pests, often requires harsh chemicals. Use of these chemicals results in potential runoff from paper mills that may accumulate in the surrounding environment and have detrimental effects upon the ecosystem and its inhabitants (Sponza, 2003). Runoff from paper mills located near bodies of water contaminates the marine environment, thus negatively impacting resident species. Studies have shown that fish populations exposed to the effluents of the pulp and paper making processes experience a decline in their rate of reproduction. Development of eggs was depressed and the lifespan of the fish decreased. A male-biased sex ratio was observed as well in the fish population (Larsson and Förlin, 2002). Lastly, the accretion of toxic and mutagenic chemicals in the lakes proved harmful to microorganisms and phytoplankton, resulting in the disruption of the natural food chain (Munkittrick et al., 1997; Sibley et al., 1997; Soiamasuo et al., 1998). Not only do pulping chemicals prove dangerous to the natural environment, they pose a serious health risk to paper mill workers. Working directly with these chemicals for extended periods of time leads to long term diseases. Various studies performed on the well-being of mill workers revealed a direct correlation between the toxicity of the pulping process and the workers' poor health (Lee et al., 2002). In all cases, the observed number of deaths was greater4 than the expected number in a range of illnesses, including diabetes, mental disorders, and various forms of cancer (See Table 1). These results reveal that the amount of dangerous chemicals used in the paper industry must be reduced in order to preserve our environment and minimize health risks to humans. Table 1. Observed and expected deaths of paper mill workers in New Hampshire. Cause of Death Observed Expected Cancer of buccal cavity & pharynx 10 5 Cancer of digestive organs 79 61 Cancer of stomach 15 8 Cancer of rectum 11 5 Cancer of larynx 6 2 Leukemia and aleukemia 12 7 Diabetes mellitus 22 15 Mental and psychoneurotic disorders 12 6 The observed number of deaths exceeds the expected number in a variety of diseases mill workers developed from working in close proximity to pulping chemicals. Adapted from Schwartz (1988). Brief Overview of Geoengineering The growing awareness of human impact upon the natural environment has led to innovation in solutions for our environmental woes. While some have proposed simply scaling back polluting activities, human ingenuity has also suggested geoengineering as a viable scheme. The concept of geoengineering entails the large-scale manipulation of the environment in order to combat or counteract the negative effects of human activity. Although the concept of geoengineering was first explored with political intent in the context of the Cold War, emerging environmental concerns in the subsequent decade brought about its examination as a legitimate means of resolving environmental problems (Keith, 2000). Two key parameters that guide the use of geoengineering are scale, which must be global, and intent, where environmental change must be the main goal. For example, mowing grass reflects intent without scale because while5 suiting human desires, it does not actually impact the environment on a global level. On the other hand, the previous manufacture of chlorofluorocarbons (CFCs) is an example of scale without intent since the depletion of the ozone layer was an unintended side effect. Geoengineering seeks to reconcile scale and intent. It is