KARACHI, June 6: Storage and transport of wheat in polypropylene bags particularly for longer distance and period, is unsafe for the material used in these bags is biodegradable and the commodity is always prone to contamination and unfit for consumption.

According to a study conducted by the Pakistan Council of Industrial Research (PCSIR), Karachi, the breaking of these bags and mixing of small pieces of polypropylene lena with wheat were observed. The bags showed rapid deterioration in the tensile strength as they got punctured on a slight mechanical jerk.

The sampling was done in the mid-2001 during the storage period, 50kg wheat in PP bags and 100kg wheat in jute sacks were exposed to two different conditions. One set of two PP bags and two jute sacks with full wheat was kept in open yard properly covered whereas the second set was kept in a warehouse.

It was observed that the bags are susceptible to heat and light, which causes their degradation. In was found that these bags did not contain any suitable light inhibitor or anti-UV material.

This leads to the breaking of PP bags and mixing of small pieces of polypropylene with wheat. Therefore the safe transportation of wheat in such bags is not possible as the light and heat causes leakage in the bags.

According to the study the insect life also becomes more active as temperature rises and because of their reparation line insects present in grain also raise the grain temperature.

Nothing has been said about the control of quality during storage itself. The reason is obvious, during storage the primary aim is simply to prevent deterioration in quality. This is done indirectly through the control of moisture, heat, air movement and by preventing the attack of microorganism and it can be done by using the right packing material and with good environment in warehouses.

It has also been observed that PP bags are not suitable for wheat storage in open yards which are exposed to direct sunlight. Another set of wheat packed in jute sacks and PP bags was kept in a warehouse, protected from sunlight and heat.

HAZARDOUS EFFECTS: The SWT, an organization working for upgradation of environmental conditions, has urged the government and NGOs to take steps for creating awareness among the people about the hazardous effects of polythene bags and induce them to use paper or cloth-made shopping bags.