AKRON, OHIO (Updated Nov. 3, 3:30 p.m. ET) -- Commodity resin prices are tumbling throughout North America, with polypropylene experiencing the steepest drop -- a 14-cent dive since Oct. 1.

Regional prices for polyethylene, PVC, polystyrene and ABS also are down in recent weeks, according to buyers contacted by Plastics News. Drops in demand and in raw material prices were connected to all of these declines.

The PP swoon ends a two-month period in which prices were flat. Prices for the material had tumbled a total of 19 cents per pound in June and July. That drop came after the market was besieged by a total of 37 cents in increases from January through May.

The October decline means 34 of the 37 cents in increases have disappeared -- and it reinforces the PP market’s reputation for extreme volatility.

Plastics are durable and degrade very slowly; the molecular bonds that make plastic so durable make it equally resistant to natural processes of degradation. Since the 1950s, one billion tons of plastic has been discarded and may persist for hundreds or even thousands of years.