Worms advise: Shop grey

Mar 08, 2013

Worm burrowing through a plastic bag

Some families shop at grocery stores that have the freshest produce. Other shoppers prefer stores with the best coupon deals. Thirteen-year-old Alexandra Page has a new option to consider when picking a food market: Which place has the most earth-friendly bags?

She shares the credit for this discovery with a few slimy, crawly worms.

Page won the Drury, New Zealand, Kiwanis Club’s science fair by testing the strength and degradability of stores’ plastic bags. Here’s her report of the prize-winning project.

Background: My name is Alexandra Page. I am 13 years old living in Auckland, New Zealand, and I did this project whilst a student at Somerville Intermediate School.

Introduction: Plastic Bag Weigh-in is a science fair project, testing the strength and investigating the degradability, of New Zealand's bigger supermarkets and retail stores such as Countdown, New World, Pak 'n' Save, The Warehouse and Kmart.


I tested the strength of the plastic bags by setting them up on stools balanced with a pole inside the handle. I would place either milk bottles, snap lock bags, or drink bottles in the bag. Then after a set time I would place another bottle in the bag until it broke.

I recorded the results and New World bag was the strongest, holding 19 kg and the Countdown bag the weakest, holding only 9.5 kg.

I investigated the degradability by placing the bags in my compost bin, which is dense with worms. I put the bags in for six weeks, and when I took the bags out I found that the bag with most worm population was the Countdown bag.

I thought the reason for the higher worm population was due to the grey coloring of the Countdown bag, because the rest of the bags were yellow or white. All the bags were brand new and placed in the same level of the compost bin.


I think my findings are a good realization for supermarkets that they under fill their bags and are using more plastic than are needed.

I also think the results of the grey-tinted bag being most attractive to worms shows the potential that color has when producing biodegradable bags.