EPA researcher calls for development of evaluation methodologies and tools to understand positive and negative impacts of algae industry
While algae are among the most potentially significant sources of sustainable biofuels in the future of renewable energy, issues remain regarding human exposure to algae-derived toxins, allergens, and carcinogens from both existing and genetically modified organisms (GMOs), as well as the overall environmental impact of GMOs, according to a critical literature review paper by Marc Y. Menetrez of the US Environmental Protection Agency’s (EPA) National Risk Management Research Laboratory, Air Pollution Prevention and Control Division.
In a paper published in the ACS journal Environmental Science & Technology Menetrez identifies and discusses human exposure and environmental impact issues, as well as current research and development activities of academic, commercial, and governmental groups.
Algae-derived biofuel will directly impact the generation of transportation fuels (biodiesel, ethanol, and petroleum), and as part of the future of renewable fuel it will also impact many environmental and economic resources. Examples of these impacts are the treatment of wastewater; capture of carbon dioxide from power plants; production of human and animal food, pharmaceuticals, cosmetics, and organic fertilizers; aquaculture; and soil nutrient recovery. Ultimately, the need to decrease fossil fuel dependence makes it imperative that algae and algae-derived products are safe to humans and the environment.
The rapid commercial expansion of the algae biofuels industry is an excellent example of sustainable product development with dramatic future potential for contributions to fuel supplies, yet many questions regarding algae production remain unanswered. The state of knowledge regarding the potential environmental impact of the production of algae and algae-derived biofuels continues to be incomplete, fragmented, and largely obscured by proprietary concerns. This knowledge is, however, changing rapidly, facilitated by research and industry and driven by economics.—Menetrez 2012
Menetrez starts by reviewing the nature of algae; constituents and byproducts of growth; environmental conditions of cultivation; genetically modified and optimized organisms; growth optimization; and extraction.
He then explores heterotrophic algae respiration and fermentation. Heterotrophs use organic compounds as their energy source as opposed to light-dependent autotrophs; i.e., they can ferment carbohydrates such as starches and sugars and produce lipids while growing in the dark. (Solazyme, as an example, uses heterotrophic algae.)
Menetrez then moves through different algal biofuel products and production pathways: conventional biodiesel transesterified from algal oil; alternative, optimized transesterification pathways; oil extraction for production of other fuels; bioethanol (direct synthesis); and direct hydrogen production.
Risk association. Depending on the algae organism and the process used, the constituents of the algae biomass and process stream can vary, he notes.
A typical process might involve microorganisms such as bacteria, mold, and yeast, including GMOs, and a wide variety of ingredients used to generate the algae and convert this biomass into a desired end product. The contents could also have potential human health risks such as those from infection (bacteria, mold, yeast, and GMOs) and exposure to allergens, toxins, carcinogens (endotoxins, mycotoxins, proteins, and organic and inorganic chemicals), antibiotics (used to prevent unwanted biological growth), enzymes (used to hydrolyze cellulose), chemicals (process additives), and acidic and caustic materials (used to hydrolyze cellulose).
The biofuel production industry is composed of many companies, each of which has adopted its own process and, for many, its own GMO form of algae. Each proprietary process design, and the reagents used (e.g., microorganisms, enzymes, chemicals), will determine the quantity and nature of waste produced....It is unclear what the impacts of release of these materials might be, but without a more complete understanding of the composition and amounts produced by the various processes, it is impossible to adequately estimate the risk associated with these materials.—Menetrez 2012
Toxicological impacts. Freshwater algae, marine algae, and cyanobacteria all produce toxins, Menetrez found. These toxins can induce dermatitis, neurological disruptions, and hepatotoxicity or liver failure. Point and non-point source discharges into waterways can cause increased nutrient levels in marine and limnic environments triggering algae blooms and negatively impacting biodiversity with increased toxins and decreased dissolved oxygen levels—e.g., dead zones or fish kills.
Algae bloom formations are known to create high concentrations of toxins, which can be controlled by limited water volume, warm water temperature, high nutrient concentrations, high pH, low CO2, and the low nutrient uptake rate demonstrated by zooplankton. Numerous lakes, rivers, sounds, and oceans have experienced pollution from algal blooms that generate many toxins such as peptide hepatotoxin microcystin-LR. Human and animal exposures usually occur through drinking water ingestion, recreational activities, absorption by contact, or inhalation. Knowledge of the effects of many toxins of algal origin on humans and animals is limited, and knowledge of the effects of GMO microalgae is nonexistent.
Marine microalgae can cause many human illnesses linked to the consumption of seafood and the inhalation of contaminated aerosolized toxins. They have also been responsible for the massive die-off of fish, shellfish, and marine vertebrates, as well as the corresponding mortality in seabirds, marine mammals, and other animals.—Menetrez 2012
Pollution control and remediation. Algae can have both positive (removal of excessive amounts of nitrogen (N), phosphorus (P), and sulfur (S) from municipal and agricultural wastewater and the sequestration of CO2 from stack emissions) and negative (release of toxigenic, carcinogenic, and allergenic algal products as well as viable organisms, including GMOs) environmental impacts.
Regulatory authority. A number of Federal agencies have spans of regulatory control that could incude algae. The USDA regulates GMOs from the standpoint of preventing the spread of pests, weeds, and diseases under the Federal Plant Pest Act (FPPA). USDA also regulates the spread of new varieties of feedstock whether they are developed by selection or hybridization, or are genetically modified.
The US Food and Drug Administration (FDA) has the authority to regulate manufactured products containing GMOs.
If the gene-modified organism expresses a pesticide or functions as a pesticide, the Environmental Protection Agency (EPA) regulates it under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). Additionally, under the Toxic Substances Control Act (TSCA), EPA also controls GMOs that have no pesticide functions. An example is a bacterium engineered to produce ethanol from residue carbohydrate.
The discharge of pollutants into surface waters of the United States is regulated by the Clean Water Act, specifically through the National Pollutant Discharge Elimination System (NPDES) permit program, although the regulatory distinction of monitoring, treating, and ultimately controlling GMO discharges by NPDES permitting is unclear, Menetrez says.
Commercialization of the production of algae derived biofuels as part of the overall biofuel industry will have a profound future impact on society. Waste products that are currently discharged into the environment as contaminants will be utilized to produce much needed renewable energy sources. Now is the time to initiate the development of an algae industry evaluation methodology that allows for the advancement of knowledge and evaluation tools for authorities to best understand the potential implications.—Menetrez 2012
Marc Y. Menetrez (2012) An Overview of Algae Biofuel Production and Potential Environmental Impact. Environmental Science & Technology doi: 10.1021/es300917r