Photos: what plastic recycling numbers mean

A growing body of scientific evidence makes plastics increasingly less attractive to 'green' consumers. Hormone-altering substances seep from drinking bottles. Great plastic garbage patches swirl in the ocean. And plastic bits have been found to concentrate poisons at levels a million times higher than in the water. Many people don't even know that most plastic is made from petroleum.

But agriculture giants and small companies alike are baking plastic from corn, soy, potatoes and tapioca. Start-ups are even exploring pig urine and carbon dioxide to make plastics. Bioplastics could make up 30 per cent of the plastics market by 2030, according to Helmut Kaiser Consultancy.

Still, most plastics continue to be made from petroleum or natural gas, which, although increasingly expensive, remain cheaper than using plants. Fossil fuel plastics involve toxic chemicals to produce, can harm human health, pollute ecosystems, and are rarely recycled. Some people struggling to eliminate daily use of plastics find it nearly impossible.

To help recyclers, the plastics industry more than two decades ago started a labelling system that identifies seven major types of plastics by a numeric stamp on the bottoms of bottles. Unfortunately, the majority of UK councils only recycle the first numbers of plastic: PET and HDPE. But what do they -- and the rest of the numbers -- mean?

1. Polyethylene terephthalate (PET or PETE)
Polyethylene terephthalate (PET or PETE) is one of the most common types of plastic and is commonly found in bottles of soda, juice, water and cough syrup and jars of peanut butter. The bottoms of these containers are usually stamped with the chasing arrows symbol and the number 1, the code for PET.

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