I was aware that – each year – several Frenchmen are killed clearing unexploded WW1 munitions. I was also aware that Britain's Porton Down chemical weapons site is still X-raying and destroying WW1 ammunition found on former UK artillery ranges which contain chemical content, mostly mustard gas or phosgene. Porton Down X-ray each projectile and, if the contents are liquid, it is opened by remote control in a sealed gas chamber and incinerated.
I was not aware that a broad swath of France near the Belgian border is still defined as 'red zone' due to chemical or bacterial contamination from more than 100 years ago. Some of this comes from chemical weapons but much of it comes from other sources and includes chemicals such as arsenic or remaining bacteria from rotting animals or people. This area is the size of the state of Hawaii or twice the area of Wales.
Ploughing in former red zone areas still turns up many tons of ammunition which the local French call "the iron harvest".
The latest Simon Whistler episode on YouTube looks at the current and future effects on the flora and fauna of north eastern France.
YouTube link
The red zone land is not farmed, no one lives in these areas, while even wood cut from this area cannot be used to make wine barrels in case the chemicals in the trees leach out into the wine. The livers of wild boar shot in this area are contaminated with heavy metals while (in 2012) some 500 local villages recently discovered their water supplies are still contaminated.
There are some bright spots. The removal of man has allowed nature to bounce back in some areas where flooded shell craters have been found to benefit certain species. This has also happened at Chernobyl, a radioactive contaminated area.
Some North American species have been found to be growing in the area and it is possible that these species came in as seeds and pollen on the uniforms of US doughboys.
Barry