The recent letters from Neil Young and Dr Jimmy Begg, taken together reinforce the following facts: plastics are now fundamental to living; the low density of plastics legislates against them being giving priority while our current waste recycling and diversion targets are weight-based; apart from the green and environmental enthusiasts, most of the public will continue to discard plastics and other litter from our daily living.

The petrochemical industry has the technology to "crack" mixed plastics wastes into their component hydrocarbon fractions. It is thought one plant could handle all Scotland's used plastics at a capital cost of £7m-£10m. If a financial package could be put in place in which plastic waste had an enhanced value, most of it would disappear from the waste stream. And, of course, there's the value of the end-products.

There is precedent for fiscal intervention: the introduction of landfill tax has transformed waste treatment, recycling and disposal beyond all forecasts in the past decade.

John F Crawford, Public Relations Officer, Chartered Institution of Waste Management in Scotland, 8 Manderston Meadow, Newton Mearns.

If Dr Begg is aware of "thousands" of marine and land animals dying from ingested plastic (Letters, April 6), then I wish he would identify his sources, for I cannot find them. Here are some facts. In 2003, nine animals were reported to the SSPCA as being entangled with plastic bags. In the same year, 1334 animals were reported to have been damaged by motor vehicles out of 88,235 reported incidents. While even one incident is too many, let us have some intelligent perspective to the respective damage to wildlife.

As far as marine life is concerned, a Newfoundland report concluded that 25,000 sea creatures were killed by human unanticipated intervention. In that report, which analyses the causes, plastic bags were not even mentioned. I suspect far more are killed by returns to the sea by fishing boats, and currently the biggest threat to the lives of seabirds, according to the RSPB website, appears to be commercial fishing for sand eels.

The figure of 16,000 tonnes of extra waste I mentioned in my first letter comes not from my fantasy, but from a report instigated in 2004 by the Scottish Executive, to determine the consequences of a tax on plastic bags. Dr Begg is correct to say this figure was based on "dodgy premises". These were certainly not my premises as the report came to this conclusion by using the dodgy premise that 30% of all shoppers would use no bags at all. The additional volume these extra tonnes require in landfill annually has been estimated at some 170,000 cubic meters.

Dr Begg suggests the use of cardboard containers for milk. These have been in use since the middle of the past century, but plastic or wax must be used to protect the milk from contamination and for waterproofing. He calls for recycled materials to be used. Not in direct contact with food, I trust, for that is against the law unless provenance of the recyclate is known. Most of the measures he suggests are heavier, bulkier, more expensive and, when they degrade, they produce carbon dioxide and methane, yet we are all trying to reduce our greenhouse gas emissions. Doesn't he know we already have close to a million tonnes of paper and card waste in our household garbage and we are struggling to make any recycling impression on that?

You would think that jute and cotton bags are fine for shopping, until it rains or you spill milk or bleach or soil from vegetables into them, when they smell and contaminate other purchases. Check the inside of the three available jute shopping bags from Tesco, John Lewis and Booths. All are lined with polythene. To negate the potential insect infestation in jute, the product is bathed in kerosene - not something I would want in proximity to my food. Both cotton and jute bags, in the main, originate in the subcontinent, are hand-made, and turned inside out when stitched. The hygiene and cleanliness of that continent is considered by many to be less than acceptable, but you can always use more energy by washing them. Another fact to consider: one 40ft container holds 55,000 standard size jute carrier bags while the same container holds some 3.5 million supermarket polythene bags. So, 63 containers for the jute against one for plastic, then 44 pallets going around Scotland delivering to stores for plastic and 2800 pallets for the jute.

I revert to my original letter, the public cause litter and we have the laws in place to deal with that if only the authorities had the conviction to enforce them. I think at least we might agree on that.

Aye, Jimmy, a little knowledge is indeed a dangerous thing, even for an educated and practical Scot.

J Neil Young, 13 Ewing Walk, Glasgow.