MICROPLASTICS: TROUBLE IN THE FOOD CHAIN Plasticized food chains
Numerous studies in recent years have provided more evidence on the presence, distribution, and starting sources of microplastic. However, the current stage of knowledge does not provide a definitive explanation of how microplastic contaminants interact chemically and physiologically with various organisms at different trophic levels. Ultimately, the risks microplastics pose to human health through consumption of contaminated food need to be considered, but these are still difficult to determine. Researchers are attempting to answer these questions with focus on specific areas. First is the level of exposure.
In a recent study, a quarter of the marine fish sampled from markets in Indonesia and California, USA, were found to have plastic debris and fibres from textiles in their guts.33
Besides
seafood, emerging evidence shows that the microplastics, especially synthetic fibres, have been detected in a variety of foods, including drinking water, beer, honey, sugar, and table salt.34-36
Many POPs are hydrophobic, meaning they are repelled by water. When these chemicals encounter plastics in lakes and oceans, they are absorbed into the plastic surface. The degree of adsorption varies widely depending on different characteristics of the POP and its host, as well as other environmental variables. However, plastic resin pellets collected from the oceans and beaches have been found to contain POPs at orders of magnitude higher concentrations than the water.39
Heavy metals
Heavy metals normally occur in nature and are essential to life, but can become toxic through accumulation in organisms. Arsenic, cadmium, chromium, copper, nickel, lead and mercury are the most common heavy metals which can pollute the environment. Sources of heavy metals include mining, industrial production, untreated sewage sludge and diffuse sources
The presence of microplastic in foodstuffs could
potentially increase direct exposure of plastic-associated chemicals to humans and may present an attributable risk to human health. However, on the basis of current evidence, the risk to human health appears to be no more significant than via other exposure routes.6
Many chemicals of concern, such as heavy metals and persistant organic pollutants (POPs) are present in the marine environment, and are taken up by marine organisms. Research has shown that harmful and persistent substances both bioaccumulate over time and biomagnify as predators eat prey, especially in species high in lipids (oils and fats). Depending on how much an organism consumes and how high it is on the food chain, each assumes some of the chemical burden of the prey and of the environment.37
manner seafood can become contaminated, particularly in higher-level predators such as tuna and swordfish, causing concern for human health, in some circumstances.38
38 Persistent organic pollutants
Persistent organic pollutants (POPs) are chemical substances that remain in the environment, are transported over large distances, bioaccumulate through the food web, and pose a risk of causing adverse effects to the environment and human health. POPs include pesticides such as DDT, industrial chemicals such as polychlorinated biphenyls (PCB) and unintentionally generated chemicals such as polychlorinated dibenzo-p- dioxins (PCDD) and polychlorinated dibenzofurans (PCDF)
Bioaccumulate In this
The accumulation of a substance, such as a toxic chemical, in various tissues of a living organism. Bioaccumulation takes place within an organism when the rate of intake of a substance is greater than the rate of excretion or metabolic transformation of that substance
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77