A study carried out by researchers at the Huddersfield University has revealed that Bristol has a rat population that is completely resistant to poison. Also, the number of such rats is on the rise, which is a bit alarming.

The team has found that poisons such as bromadiolone and difenacoum are having no impact on rats in the city. Also, varied other areas in the outskirts of the region, including Somerset, Bath and Gloucestershire, possess these kinds of rats.

It is being feared that the buildup of poisons in rats this way can somehow enter the food chain, if cats or birds prey on them. Experts have been holding responsible the pest controllers for this upsurge in the resistant rat population. They say that strong doses of poisons are missing, which ultimately are helping rats to resist the same.

Another concern is if all the rats without a mutation are killed by poisons, the city may realize a whole population of rats defiant to venoms. It is being suggested by the head of biological sciences Dr. Dougie Clarke that poisons’ doses should be upgraded so as to annihilate super rats. "It's not the dosage that's the problem, it's these compounds specifically”, he added.