The Problem

Independent studies have shown that chemical herbicides can cause numerous health and environmental problems, yet billions of dollars of herbicides are used annually, by both individuals and industry. Side effects can arise from intentional or unintentional direct consumption, improper application resultingin the herbicide coming into direct contact with peopleor wildlife, inhalation of aerial sprays, or food consumption prior to labeled preharvest intervals. ‘Green chemistry’ (also called sustainable chemistry), is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances. As such, green chemists seeks to reduce and prevent pollution at its source, in large part through the use of environment-benign substances.

The Idea

This project, led by American high school student Grace Brosofsky, focuses on natural herbicides, which offer an alternative to chemical herbicides and allow efficacy (weed control) to be achieved without damage being done to the environment. Brosofsky has engaged in research on how potential herbicidal ingredients could be best combined to create a non-toxic solutionfor post-emergent weed control (weed control for already growing plants). Her research has been centered on three natural herbicides that have shown potential on the basis of previous studies: clove oil, which acts by damaging the plant’s cuticle and cell membrane, resulting in the loss of electrolytes; vinegar, which also functions as a herbicide and dehydrates areas of contact by dissolving plant cell membranes and causing leakage; and d-limonene, derived from citrus fruits, which has been used in the past as a natural contact herbicide.

As hypothesized, a tank mix of vinegar and d-limonene appeared to be the most effective natural post-emergent herbicideat a 100 gpa application volume although it did not demonstrate high efficacy at a 20 gpa volume, and tank mixes were generally very effective. Of the three primary herbicides, vinegar achieved the highest efficacy at 100 gpa. Brosofsky’s research has also shown that certain substances are able to demonstrate high efficacy on broadleaf weeds but are not effective enough to kill grass. These substances could serve as potential herbicides for lawn weed control in which the object is to eliminate weeds while leaving grass primarily unharmed.

Potential Impact

As hypothesized, a tank mix of vinegar and d-limonene appearedto be the most effective natural post-emergent herbicideat a 100 gpa application volume although it did not demonstrate high efficacy at a 20 gpa volume, and tank mixes were generally very effective. Of the three primary herbicides, vinegar achieved the highest efficacy at 100 gpa. Brosofsky’s research has also shown that certain substances are able to demonstrate high efficacy on broadleaf weeds but are not effective enough to kill grass. These substances could serve as potential herbicides for lawn weed control in which the object is to eliminate weeds while leaving grass primarily unharmed.

Social Value

As noted, Brosofsky’s project fits within a wider ‘green chemistry’movement committed to identifying products and processesthat reduce the prevalence of hazardous substances in everyday life. The public exposure that would come with a scale-up of her research - especially when combined with her profile as a young, talented scientific mind - would provide socialvalue in broadening further the debate around industrial chemical use in situations where it threatens peoples’ health or the environment. ‘Green chemistry’ technologies provide a number of benefits, including reduced waste, safer products, the reduced use of energy and resources and improved competitiveness of chemical manufacturers and their customers.

Moreover, ‘green chemistry’ encourages innovation and promotesthe creation of products that are both environmentally and economically sustainable - a goal with clear social value in a contemporary world where the tension between the health of the environment and economic imperatives is of enduring societal concern.