**3.2 Legal and regulatory framework on MP**

Microplastics are subdivided into two groups: primary microplastics and secondary microplastics [26]. The distinction between primary and secondary microplastics is based on whether the particles were originally manufactured to be that size (primary) or whether they have resulted from the breakdown of larger items (secondary) [44]. It is a useful distinction because it can help to indicate potential sources and identify mitigation measures to reduce their input to the environment. Primary microplastics include industrial 'scrubbers' used to blast clean surfaces, plastic powders used in molding, micro-beads in cosmetic formulation, and plastic nanoparticles used in a variety of industrial processes [44, 45]. In addition, spherical or cylindrical virgin resin pellets, typically around 5 mm in diameter, are widely used during plastics manufacture and transport of the basic resin 'feedstock' prior to production of plastic products. Secondary microplastics result from the fragmentation and weathering of larger plastic items. This can happen during the use phase of products such as textiles, paint, and tires, or once the items have been released into the environment [44]. The rate of fragmentation is controlled by several factors [46].

*Microplastics and Environmental Health: Assessing Environmental Hazards in Haiti DOI: http://dx.doi.org/10.5772/intechopen.98371*

Plastics can be lost to the environment across their entire value chain [47], which creates different opportunities (and challenges) to prevent leakage into technical and natural systems [48]. In this context, it is useful to frame the separate but interconnected issues of plastic pollution, which are nestled into one another [47]. A list of microplastic sources entering the environment is presented in **Figure 3**.

Some sources and pathways are interconnected (e.g., mechanical stress, plastic waste, plasticulture) and some sources are stand-alone (e.g., primary microplastics in products, targeted applications, or transportation losses), but collectively all sources are part of the puzzle of how microplastic enters the environment.

**Figure 3.**

*Environmental sources of pollution by microplastic [47].*

#### **Figure 4.**

*Sources of microplastics in natural ecosystems [50]: (a) different color and shaped microplastics collected from seawater, shorelines, or marine sediments; (b) photomicrographs of the microplastics in facial cleansers; (c) scanning electron microscopy image of microbeads found in cosmetics; and (d) scanning electron microscopy image of a typical fiber from fabric [50].*

Microplastics in the environment are generally supposed to be a heterogeneous aggregate of particles, which can be of both primary and/or secondary origins. However, whatever the group to which they belong, depending on their physical and chemical properties, the size and shape of the particles, the crystallinity, the surface chemistry and the composition of the polymers and additives, the toxicity of microplastics can be crucial for the environment [49]. In a critical review on the sources and instruments of microplastics in marine ecosystems, Wang & al [50] present a figure in which the landbased origins of primary and secondary MP are well explained (**Figure 4**).

Although there is no specific international marine legislation regarding microplastics so far, many proactive countermeasures have been taken – voluntary or legally binding practices at international, regional, and national levels [47]. Indeed, the available literature on marine pollution reports the existence of three global international conventions that deal with the problem of plastic waste in the marine environment at the beginning of the 1970s: (i) the United Nations Convention (UN) on the Law of the Sea [51], (ii) the International Convention for the Prevention of Pollution from Ships (1973) as amended by the Protocol of 1978


#### **Table 5.**

*Overview of current legislation, regulations and instruments related to microplastics [50].*

*Microplastics and Environmental Health: Assessing Environmental Hazards in Haiti DOI: http://dx.doi.org/10.5772/intechopen.98371*

(MARPOL 73/78) [52] and (iii) the Convention for the Prevention of Pollution by Dumping of Wastes and Other Matter (London Convention or LC, 1972) [53].

**Table 5** shows an overview of current legislation, regulations and instruments related to microplastics. Considering the abundance of microplastics in the environment, their ability to absorb pollutants, their impact on living organisms, the health and environmental authorities in several countries have applied the precautionary principle by adopting a legal framework on MP. However, uncertainties and gaps in the evidence regarding the effects of microplastics on the environment and on human health prevent the adoption of more restrictive measures, with the precautionary principle - in line to the World Trade Organization (WTO) obligations on international trade - only playing a minor role [54]. Available information on current regional and national instruments related to microplastics is discussed in Wang & al. [50].

#### **4. Impact of microplastics on living organisms in natural ecosystems**

The global plastics production has increased from 1.5 million tons in the 1950s to 335 million tons in 2016, with plastics discharged into virtually all components of the environment [55]. The MPs present in the environment result from the successive breakdown of larger plastic pieces or from the direct input of micro- and nano-sized particles used in various industries and products available to consumers [56]. Indeed, during their production, industrial and domestic use, and after such processes, a considerable part of the plastics produced globally end up in the environment. Moreover, Plastics rarely biodegrade but through different processes they fragment into microplastics and nanoplastics, which have been reported as ubiquitous pollutants in all marine environments worldwide [55]. In fact, plastics represent one of the fastest-growing portions of the urban waste contributing to environmental contamination and pollution, with plastic debris accounting for approximately 60–80% of all marine litter, reaching 90–95% in some areas [55, 57–59].

#### **4.1 Environmental occurrence**

According to Lambert et al. [5] "Upon their release to the environment MPs are transported and distributed to various environmental compartments. The distances that an individual item will travel depends on its size and weight. Lightweight materials can be readily transported long distances via a windblown route or carried by freshwater to eventually accumulate in the oceans. During heavy rainfall events, roadside litter can be washed into drains and gullies, and, where the topography is favorable for it, can be carried to the sea". **Figure 5** shows a conceptual model illustrating degradation pathways for polymer materials [5].

Once in the environment MPs are degraded through abiotic or biotic factors working together or in sequence; these processes cause the polymer matrix to disintegrate, resulting in the formation of fragmented particles of various sizes and leached additives [5]. According to Lambert et al. [5] "there is a broad literature dealing with the degradation of various polymer types under various conditions. Most of these studies were performed in the laboratory and had a major focus on samples exposed to high-energy UV irradiation".

In the environment, MPs constitute a matrix of pollutants, composed of several monomers and polymers (PE, PP, EPS, PET, PMMA, PTFE, PA, PU, etc.), metal catalysts, additives: phthalates, retardants. Flame, bisphenols A and F, etc.), loading materials (talc, Ti dioxide), adsorbed environmental pollutants (organic and

*Conceptual model illustrating degradation pathways for polymer materials [5].*

inorganic, pathogenic agents, etc. The exposure of living organisms to MPs leads to consider the interactions between the combined effects of different pollutants. The characterization of exposure to microplastics will depend on: (i) the number of particles; (ii) size distribution, shape, surface properties, polymer composition and particle density; (iii) the duration of the exposure; (iv) the kinetics of absorption and desorption of contaminants, vis-à-vis the plastic and the organism; and (v) the biology of the organism [44].

#### **4.2 Environmental effects**

Microplastics have been detected in sediments, surface waters, estuarine and marine waters [60–62]. The negative effects of microplastics on algae, mussels, fish, and other organisms have been the subject of several studies and have shown [20, 63–66]. Given the difficulty for large filter-feeding organisms (fins, whales, ..) and zooplankton to differentiate between microplastics and food itself [27, 67], cellular intoxication has been documented by ingestion by inadvertently adhered microplastics with other pollutants [26, 25]. Flame retardants (chemicals derived from plastics) have been found in birds [29] and phthalates in whales and filter-feeding sharks [27]. Microplastics can affect growth and reproduction in daphnids [28].

Alimba and Faggio [55] observed effects of MPs on marine vertebrates and invertebrates, including asphyxiation by drowning, restricted diet and increased starvation, skin abrasions and skeletal injuries (which are the basis of intestinal mucosal damage, morbidity, and mortality), oxidative stress, altered immunological responses, genomic instability, endocrine disruption, neurotoxicity, reproductive abnormalities, embryotoxicity and transgenerational toxicity [55].

Present in an environment, MPs can mimic the natural food sources of living species [5]. 135 species of marine vertebrates and 8 species of invertebrates susceptible to entanglement, and 111 species of seabirds have been identified, among others,

*Microplastics and Environmental Health: Assessing Environmental Hazards in Haiti DOI: http://dx.doi.org/10.5772/intechopen.98371*

among the species that ingest plastic objects [67]. Other studies have shown that MPs wrapping loops are a threat to sea lions in California and fur seals in Australia, respectively [68, 69]. Plastic bags have been identified as the main type of debris ingested by sea turtles [70]. **Figure 6** shows a conceptual model illustrating the potential effects produced during the degradation of polymer-based materials [5].

### **4.3 Potential effects of microplastics on human health**

The primary route of human exposure to MPs is the ingestion of foodstuffs, in particular seafood which has ingested microplastics [30], processed commercial fish [71], sea salt [72], honey [73], beer, food components [73]. Most of these food products are sometimes contaminated by the presence of impurities in processing materials and contaminants in packaging [74]. The second route of exposure is inhalation of air and dust containing MPs [30]. Due to their nutritional value, seafood plays an important role in human nutrition. Indeed, the consumption of seafood represents 6.7% of all protein and about 17% of animal protein in 2015 [75]. The risk of exposure is therefore great and increases with small fish eaten whole [46].

Several studies have highlighted the evidence for the presence of microplastics in several commercial aquatic species such as mussels, oysters, crabs, sea cucumbers and fish [76–78]. The results of this work suggest that humans are exposed to microplastics through their diet and the presence of microplastics in seafood could pose a threat to food safety [76]. The potential accumulation of microplastics in the food chain, especially in fish and shellfish (species of mollusks, crustaceans, and echinoderms) could have consequences for the health of human consumers [44]. In this trophic context, the fate and toxicity of microplastics in humans constitutes a major lack of knowledge which deserves special attention. The potential

#### **Figure 6.**

*Conceptual model illustrating the potential effects produced during the degradation of polymer-based materials [5].*

accumulation of microplastics in food chains, particularly in fish and crustaceans (mollusks, crustaceans, and echinoderms), appears to be the main source of human exposure to microplastics [44]. Contamination of food products with MP could have consequences for the health of human consumers. In this trophic context, the fate and toxicity of microplastics in humans constitutes a major lack of knowledge which deserves special attention.

The translocation of microplastics from the intestine to the circulatory system and various tissues and cells in humans has been studied by several authors [44]. Indeed, Hussain et al. [79] have shown the absorption of PE particles captured in the lymph and the circulatory system from the gastrointestinal tract. Exposure of human macrophages to fluorescent microspheres of PS (1, 0.2 and 0.078 μm), demonstrated particle capture driven by non-endocytic processes (diffusion or adhesive interactions) [44].
