Whose formalin test to trust?

Recently the government conducted anti-formalin drives at various checkpoints of Dhaka city to stop the entry of formalin-tainted fruits. In doing so, they destroyed thousands of tons of fruits. A few days later, we came to know from a Prothom Alo report that several government organisations like BSTI, Department of Agriculture, BRRI etc., conducted laboratory research on fruits collected from various markets and found that not majority of the fruits, but only 40% are tainted with formalin.
Last Saturday in our Consumer Law class, we arranged a programme to test whether fruits are contaminated with formalin or not. We conducted the test with a newly invented formalin tester, about which the Prothom Alo published an article a few months back. It is a kind of liquid and one needs to use only one drop of it to test whether a food item contains formalin or not. Thus we tested mangoes, bananas, blackberries, apples, oranges and tomatoes which were collected from different markets of Dhaka. Unfortunately, all these fruits were found to be formalin-tainted. Only a single mango, collected from one's personal orchard, was found to be formalin-free.
We are so confused about different versions of test results. We request the government and the media as well to kindly tell us the truth.
T. M. Abeed Hasan
Department of Law, BUBT