**3. Materials and Methods**

Since the intensification of global trade, interventions to limit environmental pollution caused by microplastics, especially in the aquatic environment, have become a priority for international environmental organisations. Several campaigns have been carried out to monitor pollution and inform stakeholders about its effects.

These issues have taken on a global dimension through OECD efforts to collect information on microplastic pollution. In our scientific research, we used OECD databases [48] for the period of 1990–2019 for the indicators presented in Table 1.


**Table 1.** Description of the indicators used in the analysis.

Based on the collected data and literature review, we formulated the following research hypotheses:

**H1.** *At the global level, the policy to combat water pollution caused by microplastics is directly and proportionally oriented towards the reduction of regional pollution, with the awareness that this approach will have an effect of at least 98% in the total reduction in water pollution caused by microplastics. The hypothesis is a continuation of the results of the research by the authors Blanco et al., Chu et al., Dronjak et al., Karapanagioti and Kalavrouziotis, Nicolai et al., Seghers et al., Shi et al., P. Wang et al. and S. Wang et al. [4–11,53].*

**H2.** *Globally, plastic recycling mechanisms have been set up on the assumption that this will have a direct impact on reducing microplastic water pollution. The definition of this hypothesis was made in accordance with the results of the research undertaken by the authors Angelakis et al., Chakraborty et al., Kittner et al., Mehinto et al., Sá et al. and Thornton Hampton et al. [32,38–40,42,43].*

**H3.** *From the point of view of the coherence of water pollution reduction policies, there is an increasing trend in the dynamics towards the reduction in correlation errors of the indicators as the overall experience of the implementation of these policies increases. The construction of this hypothesis was based on research conducted by the authors Melchor-Martínez et al., Nikiema and Asiedu, Rius-Ayra et al. and Sadia et al. [44–47].*

**H4.** *At the EU level, against the background of intensified efforts to promote the circular economy, the disparities in terms of combating water pollution caused by microplastics are widening, especially for countries where the implementation of the circular economy is at an early stage. This hypothesis is also supported by research carried out by the authors Cook et al., Lofty et al., Rosenboom et al. and Syberg et al. [27–30].*

Using data reported by the OECD (Table 1), we performed a multiple regression correlation diagram for 15 regions in the world. It has as its pivot the dependent variable assimilated to the circular economy, i.e., the amount of plastic waste collected for recycling, which we treated in relation to the monitoring indicators of plastic waste produced at the regional level, end-of-life plastic waste and the impact of plastic pollution on the aquatic environment.

The system of regional equations for the variables in Table 1 is presented as follows:

```
⎧
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨
⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩
                        PWCRUS = 1.693 ∗ PLAEUS + 0.043 ∗ PURUS + 0.068 ∗ PWRELFUS − 0.742
                     PWCRCAN = 1.448 ∗ PLAECAN − 0.086 ∗ PURCAN + 0.143 ∗ PWRELFCAN − 0.111
       PWCROECDAmerica = 1.003 ∗ PLAEOECDAmerica − 0.173 ∗ PUROECDAmerica + 0.236 ∗ PWRELFOECDAmerica + 0.14
                PWCROECDEU = 3.874 ∗ PLAEOECDEU − 0.158 ∗ PUROECDEU + 0.2 ∗ PWRELFOECDEU − 1.7
      PWCROECDNonEU = −0.021 ∗ PLAEOECDNonEU − 0.272 ∗ PUROECDNonEU + 0.509 ∗ PWRELFOECDNonEU − 0.299
          PWCROECDASIA = 0.094 ∗ PLAEOECDASIA − 0.275 ∗ PUROECDASIA + 0.592 ∗ PWRELFOECDASIA + 0.115
      PWCROECDOceania = 21.215 ∗ PLAEOECDOceania − 0.009 ∗ PUROECDOceania − 0.204 ∗ PWRELFOECDOceania + 0.003
  PWCROECDLatAmerica = 1.644 ∗ PLAEOECDLatAmerica + 0.084 ∗ PUROECDLatAmerica − 0.175 ∗ PWRELFOECDLatAmerica − 0.083
                 PWCROthEU = 11.154 ∗ PLAEOthEU − 0.014 ∗ PUROthEU − 0.141 ∗ PWRELFOthEU + 0.045
              PWCROthEurasia = 4.762 ∗ PLAEOthEurasia + 0 ∗ PUROthEurasia − 0.03 ∗ PWRELFOthEurasia − 0.025
    PWCRMENorthAf rica = 1.096 ∗ PLAEMENorthAf rica − 0.029 ∗ PURMENorthAf rica − 0.005 ∗ PWRELFMENorthAf rica + 0.065
             PWCROthAf rica = 0.611 ∗ PLAEOthAf rica + 0.073 ∗ PUROthAf rica − 0.105 ∗ PWRELFOthAf rica − 0.06
    PWCRNonOECDASIA = 1.06 ∗ PLAENonOECDASIA − 0.037 ∗ PURNonOECDASIA − 0.048 ∗ PWRELFNonOECDASIA + 0.156
                    PWCRChina = 5.051 ∗ PLAEChina + 0.05 ∗ PURChina − 0.158 ∗ PWRELFChina − 0.525
                     PWCRIndia = 5.577 ∗ PLAEIndia + 0.035 ∗ PURIndia − 0.226 ∗ PWRELFIndia − 0.029
                                                                                                                         (1)
```
From the analysis of the system of equations constructed on the basis of the β coefficients of the 15 regional models, it is evident that the variable that best correlated with the outcome indicator of circular economy efficiency (dependent variable) is the indicator of monitoring the impact of plastic pollution on the aquatic environment. Thus, the impact of the circular economy results in long-term effects on the reduction of microplastic pollution, especially in China, India, Oceania and Europe (see Figure 2).

**Figure 2.** Correlation diagram of the effects of the implementation of the circular economy on the reduction of water pollution caused by microplastics (PWCR vs. PLAE).

The diagram shows that, at the level of the performing sample, the average correlation is 500%, i.e., the impact of reducing environmental plastic pollution generates a 5-fold reduction in the impact of microplastics on the aquatic environment in the circular economy, the maximum magnitude belonging to the Oceania region, where the impact is 21 times greater. At the European level, in OECD member countries, the impact is up to 3.8 times and up to 11 times in non-OECD member countries.

Non-EU countries show the lowest correlation between the two indicators, with an inversely proportional variation of 0.21%. This means that, in these countries, the impact of the circular economy is low and the strategies to reduce microplastic pollution are not in accordance with the global and European action guidelines.

After using a multiple regression correlation at the regional level (see Figure 3), it was observed that there is an inversely proportional relationship between plastic consumption and use in the regional circular economy of the USA, Canada, OECD America, OECD EU, OECD Non-EU, OECD Asia, OECD Oceania, Other EU, ME North Africa and non-OECD Asia. The average value of the inverse correlation is 10%. For the other regions analysed in the sample, the correlation is directly proportional, but reduced by a maximum of 8%, which shows that, in relation to the development objectives of clean industry, plastic consumption does not show significant changes. We consider this a major vulnerability of pollution policies, which, in this light, should focus additional efforts to improve public policies.

**Figure 3.** Correlation diagram of the effects of circular economy implementation on plastic use by region (PWCR vs. PUR).

Figure 4 shows a significant disparity in the correlation between the implementation of the circular economy and the reduction of the mass of end-of-life plastic waste, where developed regions of the world (USA, Canada, OECD America, OECD EU, OECD Non-EU, OECD Asia) have higher correlation rates. These regions have access to superior technologies to combat microplastic pollution according to its chemical properties with significant biological impact. The average correlation reaches 30%, with a maximum of 60% in the region of Asian OECD member states.

In the other regions analysed, the correlation is inversely proportional, which means that the policy to combat microplastic pollution does not meet the proposed goal, one explanation being the orientation of these regions towards commercial expansion and extensive economic growth.

**Figure 4.** Correlation diagram of the effects of the implementation of the circular economy on end-of-life plastic waste (PWCR vs. PWRELF).
