Although dozens of sugarcane plantations once existed in Hawaii]], the Hawaiian Commercial and Sugar Company (HC&S) on Maui is the state’s only remaining sugar producer. With approximately 36,000 acres worth of sugarcane and a large industrial mill alongside Maui’s major highway, the business maintains a highly visible presence on the island. As the largest private landholder on the island, HC&S has a great economic power that necessitates environmental responsibility. Debate surrounding the sugarcane company’s practices has become a popular and polarizing issue, and the Maui’s major newspaper, The Maui News, publishes multiple letters to the editor regarding sugarcane each week. Empirical studies point to some of the potential health and environmental impacts of growing and burning sugarcane on Maui.
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The Sugar Harvesting Process
Sugarcane is a plant that thrives in warm, tropical regions such as Brazil, Hawaii, and Caribbean islands. Despite the geographic diversity of sugar plantations, the procedure for growing and harvesting sugarcane throughout the world is rather uniform. First, the stalks grow for about two years, or until they reach a mature height around eight feet. The fields must be kept well irrigated throughout the maturation period, as sugarcane is an exceptionally water-intensive crop. Just prior to harvesting the sugarcane, the fields are burned to remove any leaves, waste, or excess foliage surrounding the stalks. The cane is burned by either allowing a fire to progress freely throughout the field or by incinerating stalks row-by-row with a flamethrower. Then, the stalks are immediately cut and transported to mill for processing. Reducing the time between burn and harvest is critical because after the stalk is burned, sucrose compounds within the sugarcane begin to form alcohols that cannot be used for sugar production. Upon arrival at the mill, cane stalks are washed, cut, and juiced to extract the sugar syrup. Remaining fiber from the stalks, referred to as bagasse, can be used as biofuel or livestock feed. At the HC&S mill, bagasse is burned to produce energy that fuels the factory’s boilers and other processing equipment. Finally, the sugarcane syrup is boiled so that the water evaporates and crystalline, raw sugar remains.
Consequences of Burning Sugarcane
Nine months out the year, from March to November, Maui residents witness frequent plumes of smoke rising from the sugarcane fields as they are prepared for harvest. Burning sugarcane prior to harvesting has been scientifically correlated with negative impacts on human health, and could threaten the wellbeing of the Maui community. In a 2014 study funded by Brazil’s National Council of Technological and Scientific Development, 28 sugarcane field workers that were otherwise healthy had blood and urine samples taken daily to measure kidney function during the burn and non-burn seasons. These workers were not smokers, nor did any of them have a history of chronic disease. In the pre-harvest season, when the workers were doing unspecified tasks that did not involve exposure to burnt sugarcane, the analysis of blood and urine samples taken at the beginning and the end of the workday showed healthy, normal renal functioning. However, in the harvest season, when the workers were constantly exposed to smoke and ash from burnt sugarcane, blood and urine samples from the subjects showed a 20% decrease in the rate of renal filtration that caused an increased in blood-level creatinine, a marker of acute renal strain or failure. The exposure to burnt sugarcane corresponded with kidneys not properly functioning, and higher levels of toxins in the blood as a consequence. While no such study has been done on Maui, the harvesting process in the Brazilian study is essentially identical to HC&S’s burnt-harvesting process.
Another Brazilian study carried out by researchers at the University of São Paulo similarly found a detrimental correlation between sugarcane burning and the surrounding community’s health. Healthy sugarcane workers and volunteers from the towns surrounding various sugarcane plantations were examined throughout both burn and non-burn seasons. A quantitative analysis of the frequency of symptoms such as wheezing, coughing, coughing with sputum (a mixture of saliva and mucus), and breathlessness revealed a significant increase in such symptoms during the burn period. For example, reports of coughing fits from both residents and workers tripled during the harvest season. Additionally, results from blood-marker and lung function tests revealed a decrease in beneficial antioxidants and diminished lung functioning during the eight-month burn period. These ailments contribute to a condition known as oxidative stress, a state where the lungs cannot efficiently deliver oxygen to the blood. The study also acknowledges that these symptoms are probably multi-factorial and cannot be entirely blamed on the air pollutants from sugarcane burning; therefore, more research is needed to determine a definitive causation.
Criticisms
When results from empirical research put the sugarcane industry, and companies such as HC&S, in an undesirable light, the counter argument most often presented is that pre-harvest burning is the most cost effective method of harvesting stalks. HC&S administrators insist that the burnt harvest method is “critical to the company’s bottom line” and it would be economically inefficient to do otherwise. However, harvesting sugarcane without burning the stalks, or green harvesting, has been found to be just as economically efficient as burnt cane harvesting in a multi-regional study performed by agricultural researchers at the University of Florida. Sugarcane plantations in Texas, Louisiana, and Puerto Rico have proven that green harvesting can be done without jeopardizing the company’s profits, making it a win-win situation for both the company and the surrounding community. Green harvesting on Maui would require HC&S to upgrade their plowing machinery and harvesting equipment, but after this initial expense, profits would not necessarily be negatively affected.
Effects of Land Development
HC&S currently maintains about 36.000 acres of cropland around Maui. In the rainy season, which typically lasts from October to February, these fields are susceptible to flooding and causing runoff into the ocean; murky waters created by this runoff affect beachgoers and marine life alike.
The land development that results from maintaining large plots of sugarcane fields, as well as the use of herbicides like Diuron in those fields, could be contributing to the degradation of coral reefs around Maui. On the island of Ishigaki, located in Japan’s Okinawa Prefecture, scientists from Hokkaido University and Japan’s National Institute for Environmental Studies examined the effects of land development, specifically the presence of sugarcane fields, on the health of the island’s coral. In a study that spanned over three years, the researchers took coral samples during both the warmer summer months and rainy winter months, and measured the levels of calcification. The tendency for the corals to calcify was indicative of their overall health. The study concluded the coral samples taken around Ishigaki were more vulnerable to coral calcification in the winter than the summer, possibly as a result of the coral’s exposure to mineral runoff from the sugarcane fields.
Another study performed on Maui in the summer of 2013 focused on the effects of the herbicide used in HC&S’s fields, Diuron, on coral health. Water samples were taken at various sites and depths around Ma’alaea Harbor before, during, and after a period of heavy rainfall. The runoff samples taken after the rainfall had concentrations of Diuron exceeding 3 parts per billion, a concentration proven lethal to corals by a previous Australian study. Because the study was relatively brief, lasting about three months, the results could not cite Diuron as an absolute cause for coral depletion in Ma’alaea Harbor.