Microplastics are found in the sea, in some foods and beverages, but also in water recovered from sewage treatment plants that is destined for agriculture. The first study in Lombardy, on a wastewater treatment plant.
Plastics and microplastics in the food supply chain
Plastic at sea has been the subject of recent awareness and denunciation campaigns. The European Commission has thus adopted the ‘Circular Economy Package‘. And the
Single-Use Plastics Directive
(SUPs
).
Microplastics in the diet, in turn, begin to emerge piecemeal. Studies in recent years in the UK, Belgium, Portugal, Germany, China, South Korea, and the USA have detected invisible fragments of PET, polypropylene, polyethylene, and polyolefins on various foods. Mineral waters and beers, salt and honey, fish and shellfish, chicken gizzards.
The contamination of food with plastics However, it does not only come from single-use plastic items and fishing gear thrown overboard. Nor from food contact materials(MOCAs) and from single-use plastic items, which also release endocrine disruptors into the human body. There is also more.
Microplastics in wastewater, including following treatment
Aquatic ecosystems are exposed to the emerging risk of chemical contamination bymicroplastics (MPs). Also as a result of wastewater treatment in the dedicated wastewater treatment plants(Waste Water Treatment Plant, WWTP). (1)
This is the finding of a very recent Italian study published in ‘Science Direct. (2) Following analysis of one of the largest treatment plants in northern Italy, built in the early 2000s, with a capacity of about 1.2 million inhabitant/eq (population/equivalent).
The researchers evaluated the presence of microplastics in wastewater at the inlet (IN), removal efficiency after treatment (SET) and at the outlet (OUT), their transfer to the sludge. Samples were collected on three days of the week, and the plastic fragments were characterized in terms of shape, size and polymer composition. Finding a total removal efficiency of 84%.
Given that the plant treats about 400 million liters of wastewater each day, the potential release of MP into the receiving aquatic system is estimated at about 160 million MP/day. In addition, a large amount of MP removed from wastewater-primarily polyesters (35%) and polyamide (17%)-was detected in the recycled activated sludge. For the total amount of about 3.4 billion microplastics deposited in the 30 tons of sludge produced daily by this WWTP.
Since in agriculture the water treated by WWTPs can be used for irrigation and the sludge can be reused in fertilizers, the research results show that such plants can also be a potential source of microplastics for agroecosystems.
Moreover, the European Commission has not to date considered the human health risks associated with MPs, although their presence appears ubiquitous. (4) Nor has it established measures to monitor and mitigate their presence in waters. So much for the principles of risk analysis and precaution, by which EU law should be inspired for the protection of citizens, animals and the environment.
Dario Dongo
Notes
(1) Wastewater treatment plants are facilities where a combination of various processes (e.g., physical, chemical and biological) is used to treat industrial wastewater and remove pollutants (Hreiz et al., 2015).
Such wastewater treatment plants produce waste that contains many potential contaminants. Regenerated wastewater is usually clean enough to be used for irrigation, but usually contains higher concentrations of suspended solids (~1.5 times)
Additional insights from ISPRA, at.
http://www.isprambiente.gov.it/it/temi/acque-interne-e-marino-costiere/la-depurazione-delle-acque-reflue
(2) ‘The fate of microplastics in an Italian Wastewater Treatment Plant’, Stefano Magni, Andrea Binelli, LuciaPittura, Carlo Giacomo Aviob, Science Direct (2018), https://doi.org/10.1016/j.scitotenv.2018.10.269
(3) DM 185/03, ‘Regulation on technical standards for wastewater reuse in implementation of Article 26, Paragraph 2, of Leg. 152/99‘ indicates three possibilities for reuse of reclaimed water:
-in the agricultural field for irrigation,
-in the civil sector for street washing, supplying heating and cooling systems, and supplying dual supply networks,
-to industrial use, for fire water availability and thermal cycle washes
(4) Some university studies are cited in the recent article, published by National Geographic on 10/22/18, on
https://www.
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
