A report by the Food and Agriculture Organisation of the United Nations (FAO) suggests that agricultural soil is contaminated with a large quantity of plastic pollution potentially affecting human health.
However, the FAO stressed the “obvious need for further investigation”.
Use of plastic in agriculture
Agricultural value chains use 12.5 million tonnes of plastic products every year with an additional 37.3 million tonnes for food packaging.
With no viable alternatives its demand is set to increase, according to the report. Industry experts estimate that global demand for greenhouse, mulching and silage films will increase by 50% to 9.5 million tonnes in 2030.
By far, the largest users are crop production and livestock sectors collectively accounting for 10.2 million tonnes/year, while Asia was estimated to account for almost half of global plastic usage.
FAO deputy director-general, Maria Helena Semedo said:
“This report serves as a loud call… to facilitate good management practices and curb the disastrous use of plastics across the agricultural sectors.”
The wide use of plastic in agriculture helps increase productivity including through the usage of: Mulch film to reduce weed growth; tunnel and greenhouse films and nets to protect and boost plant growth, extend cropping seasons and increase yields; and coatings on fertilisers, pesticides and seeds to control the rate of release of chemicals or improve germination.
Furthermore, plastic products help food maintain its nutritional qualities thus improving food security and reducing greenhouse gas (GHG) emissions.
“While they can increase productivity and efficiency in all agricultural sectors and help minimise food loss and waste, plastics are a major source of contamination,” Semedo added.
Risk of contamination
Sorting and recycling of plastics is difficult as polymers, which are materials consisting of very large molecules, and additives are blended into plastics. Only few microorganisms are capable of degrading in such a way, meaning that they may fragment and remain in the environment for decades.
Of the estimated 6.3 billion tonnes of plastics produced up to 2015, almost 80% has not been disposed of properly, according to the report.
The widespread, long-term plastic use and the lack of systematic collection and sustainable management leads to accumulation in soils, which are estimated to contain larger quantities of microplastics (plastics less than 5mm in size) than oceans.
Since 93% of global agricultural activities take place on land, soils are likely to be the principal receptors for damaged, degraded or discarded agricultural plastics.
Microplastics are thought to present specific risks to animal health, but recent studies have detected traces of microplastic particles in human faeces and placentas.
Derived from agricultural plastic products, microplastics are of increasing concern as they have the potential to adversely affecting human health, according to the FAO report.
Solutions and further investigation
Outlined in the FAO report are several solutions based on the 6R model which comprises six methods: Refusing; redesigning; reducing; reusing; recycling; and recovering.
Agricultural plastic products identified as having a high potential for environmental harm include non-biodegradable polymer coated fertilisers and mulching films.
As an alternative for films, the FAO recommends using a biodegradable film, organic materials or cover crops to avoid the use of plastics for mulching practices.
“There is an urgent need to better monitor the amount of plastics used and that leak into the environment from agriculture,” the FAO warned.
“While there are gaps in the data, they shouldn’t be used as an excuse not to act,” the organisation has said.