Usually, when microplastics and the contaminants they sequester are detected in seafood, they are in the animal’s stomach. Except for shellfish, humans tend to remove and discard the stomach of the seafood they consume. The risk of chemical contaminants being transferred to humans would then depend on: i) the retention time of the particles in the fish gut, ii) the rate and degree to which contaminants are released from the plastic and cross the gut wall, iii) the degree to which fine particles might be translocated from stomach to other tissues of animals, and iv) the degree to which chemical contaminants can transfer from the consumed seafood to human body.22,40
At present scientists only
have results from laboratory feeding studies using non-commercial fish species to examine contaminant transfer and accumulation in the tissues and that note any altered predatory behaviour. A number of these experiments with a range of marine species show that microplastics are able to translocate from stomach to other organs such as liver and hepatopancreas.41,42
Currently there is
insufficient evidence to assess the potential for transfer of these contaminants to the fish flesh, and hence be made available to predators, including humans.6,40
Different types of microplastics found in the Francisco Bay DDTs
PCBs (Cl)n (Cl)n DDT
• Industrial products for a variety of uses including dielectric fluid, heat meduim, and lubricants • Endoctrine disrupting chemicals
absorption from ambient seawater
HCH H H
Cl Cl H Cl H • Insecticide Modified from the International Pellet Watch (2016)44 Plastic resin pellets
Plastic resin pellets are the raw material for the manufacturing process of plastic items
Opaque spherules, fragments and fibres; (a/b) transparent spherules with gas bubbles, polymethylmethacrylate; (c/d) opaque spherules, polystyrene
Source: Mani et al. (2015)26 Source: Mani et al. (2015)26 39 Cl Cl
Plastic Pellet
H
Cl H
additives
Nonylphenol (NP) OH
C9H19
• Antioxidant (TNP) • Raw material of plastic additives • Endocrine disrupting chemicals
Courtesy of International Pellet Watch (2016)44 Cl DDE Cl
• DDT and its metabolites such as DDE and DDD.
• DDT was used as insecticides • Endoctrine disrupting chemicals
DDD Cl © National Geographic
Video Link:
https://www.youtube.com/watch?v=ZHCgA-n5wRw Photo Credit: Coprid/
Shutterstock.com
Microplastic typically found along the Rhine River Microplastic typically found along the Rhine River.
Cl CH Cl CCl3 CCl2 C Cl CH CHCl2
Biomagnify
The increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain. As a result of biomagnification, organisms at the top of the food chain generally suffer greater harm from a persistent toxin or pollutant than those at lower levels.
Video: Are microplastics in our water becoming a macroproblem?
UNEP FRONTIERS 2016 REPORT
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