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  1. Plastics are an integral part of our daily lives. They are generally made of a certain type of monomer (the building block of each plastic type) and several additives, which give the plastic particular characteristics. There are thousands of additives used, with purposes ranging from giving the plastic a certain colour (such as titanium dioxide, used as a white pigment) to stabilising the plastic (such as 2-benzotriazol-2-yl-4-methyl-phenol, also known as Tinuvin®). In our homes, offices, shops, leisure pursuits and transport, most items we come in contact with have some plastic content. However, certain uses will be more obvious than others; for example, we use plastics for containers from milk to shampoo to microwave meals. There are many types of plastics used for packaging, commonly identified by a number included next to the recycling symbol. These numbers are known as the Resin Identification Coding (RIC) system, which indicates the resin from which the plastic was produced. Worryingly, it is known that chemicals contained within the plastic can leach into the food or onto the skin, particularly under high temperatures,[1] making some plastic containers safer than others purely based on their ingredients. Whilst the safest option may be to replace our use of plastic with alternatives such as glass, being able to identify the safest types of plastic can also help us to minimise exposure to toxic chemicals. Polyethylene is the most widely used plastic in the world, and two of its derivatives, marked with the numbers 2 or 4, are considered very safe. Plastic marked with a number 2 is high-density polyethylene (HDPE), which is produced from petroleum. It is strong, tough, moisture-proof and relatively impermeable to gases.[2] [3] HDPE is a relatively stable plastic that can withstand high temperatures, and its use in food and drink containers is therefore considered safer than some other plastics. HDPE is used in numerous containers, including milk, water, juice, bleach, detergent, shampoo, yogurt and margarine, as well as cereal box liners. Low-density polyethylene (LDPE), plastic number 4, is a thinner, more flexible polyethylene derivative. It is commonly used in frozen food bags, plastic wraps, coatings for milk cartons, hot and cold beverage cups, some squeezable bottles (e.g., honey and mustard) and food storage containers. As it shares many of the same properties as HDPE, it is also a relatively safe plastic for food storage. A thermoplastic polymer called propylene (PP), designated plastic number 5, has similar uses to polyethylene. It is generally stiffer and more heat resistant, so it is often used for serving hot food, and it is considered to be microwave and dishwasher safe. PP is also used in containers for ketchup, yogurt, cottage cheese, margarine and syrup, as well as in straws, bottle caps, water filters and baby bottles. Not all plastics are safe when in contact with food, however. Plastics designated as RIC number 1 contain polyethylene terephthalate (PET, PETE or polyester), which may leach antimony.[4] Plastic number 3, polyvinyl chloride (V, vinyl or PVC), may contain and possibly leach numerous harmful chemicals such as bisphenol A (BPA), phthalates, lead or dioxins. Polystyrene (PS), designated RCI number 6, may leach styrene. An RCI designation of 7 indicates any other plastic not specified by categories 1 to 6. Polycarbonate (PC) is a common category 7 plastic, and it has raised concerns regarding chemical leaching.  It may be wise to avoid plastics designated RIC category 1, 3, 6 and 7. It should also be noted that the term ‘microwave and dishwasher safe’ only applies to the physical properties of the plastic, meaning that it will not warp when heated. This does not, however, imply that it is safe for health. Plastics on the market today can pose considerable health risks, especially given that regulations are still in an infancy stage and currently based on business self-regulation. Furthermore, even though few regulations do exist, they do not take into account the potential additive effects that come from having multiple plastic types in one product, or from using products multiple times. The tolerable daily intake (TDI) determined for one chemical may therefore be well above the amount ingested in one exposure, but multiple exposures (or exposures to multiple products) could potentially take the consumer over this safety limit. A safer and healthier alternative is to use glass containers to store food. Glass doesn’t contain the toxic additives that most plastics do, and it is inert, which means that it doesn’t react with the food contained inside it. It also means that it remains safe during high-temperature washing, microwaving and ultraviolet light exposure. Nevertheless, when using glass as an alternative, don’t forget to check the glass against toxic impurities and what the lid is made of, as toxic additive-containing plastic may also be hiding in the form of a closure seal. [1] Kubwabo C, Kosarac I, Stewart B, Gauthier BR, Lalonde K, Lalonde PJ (2009). Migration of bisphenol A from plastic baby bottles, baby bottle liners and reusable polycarbonate drinking bottles. Food Addit Contam Part A Chem Anal Control Expo Risk Assess.26(6). 928-37. [2] Bikiaris DM, Triantafyllidis KS (2013). HDPE/Cu-nanofiber nanocomposites with enhanced antibacterial and oxygen barrier properties appropriate for food packaging applications. Materials Letters. 93. 1-4. [3] Moyssiadi T, Badeka A, Kondyli E, Vakirtzi T, Savvaidis I, Kontominas MG (2004). Effect of light transmittance and oxygen permeability of various packaging materials on keeping quality of low fat pasteurized milk: chemical and sensorial aspects. Int Dairy J. 14(5). 429-36. [4] Brandão J, Moyo M, Okonkwo J (2014). Determination of antimony in bottled water and polyethylene terephthalate bottles: a routine laboratory quality check. Water Sci Technol: Water Supp. 14(2). 181-8.