For many years I enjoyed the jokey adverts that claimed that Carlsberg was “probably” the best lager in the world.

I am less amused, however, to be told now by the World Health Organisation that another translucent golden liquid that I am equally familiar with, Roundup, “probably” causes cancer in humans.

The International Agency for Research on Cancer – the World Health Organisation’s cancer agency – suggests that there is evidence that glyphosate, the active ingredient in Roundup, is carcinogenic to humans. The WHO report finds that on reexamining existing case control studies of “occupational exposure” in the United States, Canada and Sweden, there was a likely increased risk for non-Hodgkin’s lymphoma and lung cancer.

I hate to think how many hours of “occupational exposure” to glyphosate I have clocked up in my faming career. Roundup was invented in 1974 when I was still busying myself with O levels and contemplating agricultural college. By the time I started farming in the early 1980s, Roundup had established itself as an essential part of the farming landscape.

In the early years, I used to attach my crop sprayer to a John Deere 2130 fitted with a leaky Duncan cab. I wore a very primitive breathing mask, a disposable wafer thin chemical suit (which wasn’t even waterproof) and rubber gloves. With no electric controls for the sprayer I had to open the back window of the tractor cab to turn it on and off at each turn on the headland. It only required a gust of wind at the wrong moment and my cab would fill with spray drift to the point where I would occasionally have to wipe the inside of my windows to remove a build up of glyphosate residue so I could see where I was going.

Spraying equipment, tractor cabs and safety wear have all greatly improved over the years but I still worry about my exposure to agrochemicals.

As the health care workers who have volunteered to help in the fight to control the Ebola epidemic in West Africa have found, sticking to procedures to avoid any contact with dangerous fluids is incredibly difficult. Even after months of intensive protocol training they sometimes fail to remove their protective clothing without becoming contaminated with lethal fluids. If they can’t manage to keep clean what chance do I stand of getting out of my spray suit, mask and gloves without exposure to glyphosate after a long day on the crop sprayer, filling the tank, washing out the chemical containers and taking the odd break to eat my packed lunch or take a sip of flask tea?

Which reminds me that Roundup once had such a safe reputation in farming circles that a spray rep once joked with me that if I ever forgot to sugar my flask of tea before I left home in the morning, I could always sweeten it with a splash of the glyphosate. Even then it felt like gallows humour.