Rebuttal of the arguments put forward in the Letter to the Editor by Nizzetto et al.

In their Letter to the Editor, Nizzetto et al. challange a recent article in which I show that there has been unwarranted alarmism about biodegradable mulch films due to the publication of numerous articles based on preliminary data that are irrelevant for drawing conclusions on environmental risk. The tendency to over-emphasise results in order to attract attention is a growing problem in the scientific world and has been studied by many scholars.

The pathology of hype, hyperbole and publication bias is creating an unwarranted concern towards biodegradable mulch films.

The idea that it is a risk to promote biodegradable mulch films on a large scale is becoming established at academic level based on a series of articles similar in approach and conclusions. However, a critical analysis shows that the results do not justify the alarmist tones. The negative effects of hand-cut pieces of virgin material added in pots at concentrations up to 714 times the application doses are ascribed to the "accumulation" and "contamination" of "residues" and "debris" of biodegradable plastics.

Microorganisms that produce enzymes active on biodegradable polyesters are ubiquitous.

Biodegradability standards measure ultimate biodegradation of polymers by exposing the material under test to a natural microbial inoculum. Available tests developed by the International Organization for Standardization (ISO) use inoculums sampled from different environments e.g.

Is composting of packaging real recycling?

In 1994, the European directive on packaging and packaging waste introduced the principle that biodegradable packaging can be recovered together with bio-waste by organic recycling (e.g. composting).

Biodegradation of plastics in soil and effects on nitrification activity. A laboratory approach.

The progressive application of new biodegradable plastics in agriculture calls for improved testing approaches to assure their environmental safety. Full biodegradation (≥90%) prevents accumulation in soil, which is the first tier of testing. The application of specific ecotoxicity tests is the second tier of testing needed to show safety for the soil ecosystem.

Laboratory test methods to determine the degradation of plastics in marine environmental conditions.

In this technology report, three test methods were developed to characterize the degradation of plastic in marine environment. The aim was to outline a test methodology to measure the physical and biological degradation in different habitats where plastic waste can deposit when littered in the sea. Previously, research has focused mainly on the conditions encountered by plastic items when floating in the sea water (pelagic domain).

Kinetics of monomer biodegradation in soil.

In modern intensive agriculture, plastics are used in several applications (i.e. mulch films, drip irrigation tubes, string, clips, pots, etc.

Compostable cutlery and waste management: an LCA approach.

The use of disposable cutlery in fast food restaurants and canteens in the current management scenario generates mixed heterogeneous waste (containing food waste and non-compostable plastic cutlery). The waste is not recyclable and is disposed of in landfills or incinerated with or without energy recovery. Using biodegradable and compostable (B&C) plastic cutlery, an alternative management scenario is possible.

A screening model for fate and transport of biodegradable polyesters in soil.

A numerical model for predicting the fate and transport of biodegradable polyester residues in soil, following successive applications of mulch film, was developed and applied. The polymer, applied on surface soil, was assumed to be converted into by-products (monomers), according to a first order kinetics with constant K(1deg). The monomers released were assumed to sorb on soil organic matter (according to a first-order kinetics with constant K(s)), to be leached with the seepage water, through vertical advection and hydrodynamic dispersion, and biodegraded (according to a first-order kinetics with constant K(b)).