SIR - The query from E Mills (T&A, April 1) about plastic bags is interesting as the answer is not straightforward. They are made from low density polyethylene, LDPE, known as plastic film, and it can be recycled into more bags. Doing this saves two thirds of the energy used in making new ones and most of the water, and it produces only one third of the CO2 emissions. A tonne of recycled plastic saves almost two tonnes of oil.

However the bags have to be collected, and sorted and transported and many of the advantages of recycling are less clear. In Bradford only the Aire Valley Recycling scheme collects plastic film, and to set it up in the rest of the district would be expensive.

The biodegradable bags from supermarkets that contaminate the normal film, and weaken it, are an added complication and overall the only answer is not to use plastic bags in the first place.

Using traditional shopping bags means less litter, less CO2, and more oil left over for its main use - driving tractors and making fertiliser to grow the food we need. Being without plastic bags is not a hardship, but being without food is.

Keith Thomson, Heights Lane, Bradford