Industrial scale destruction of old chemical ammunition of the Great War on the western Front The hundred-year-old vorgotten contaminations

International audienceDuring the Great War, ammunition had been used on an unprecedented scale. When hostilities ceased, huge ammunition dumps remained. Unexplosed ordnances were collected on former battlefields too. There was an urgent need to dispose 2.5 to 3 million tons of hazardous ammunition during the interwar period. New methods for safely breaking down chemical shells were then developed by civilian companies when the army demobilized. This also offered the possibility of recovering valuable materials, and was a source of profit. After defusing, the rounds were emptied by perforation when the toxic contents were liquid, by steam or hot-water washing-out for TNT explosive shells and by open-burning for both chemical and explosive shells. These processes caused severe top soil contaminations especially on former burning-grounds of chemical shell. Recent research has been conducted on 9 burning-grounds in France and Belgium. To this day, no vegetation grows at some locations due to extreme high grade of heavy metal (Zn, Pb, Cd,…), ranging for Zn from 10 to 100 g/kg DM, chlorinated and /or brominated dioxin & furan (1 000 to 4 000 000 ng/kg DM), and arsenic (2 to 110 g/kg DM) when arsenical "Blue Cross" shells loaded with the sternutators diphenylchlorarsine (CLARK 1) and diphenylcyanoarsine (CLARK 2) were open-burned. Inorganic arsenical compounds are associated with organic by-products produced by the oxidation (diphenylarsinic acid) or thermal decomposition (triphenylarsine, As-PAH like phenylarsafluoren) of CLARKs. Brominated dioxin, energetic compounds (TNT, nitronaphtalin) and thianes (impurities of yperit) have been measured too. High resolution geomagnetic measurements had been conducted on a site where 1,5 million old chemical shells have been destroyed during the interwar period in Spincourt, near Verdun, leading to severe top-soil contamination, the contamination of the barley that try to grow on the spot, crops and meat destructions and the sequestration of the ground. Open-detonation pits and systems of burning trenches have been recognized and carefully probed using a backhoe under high security constrains. To this end, food products of plant and animal origin were sampled in 2015-2016 and contaminant analyses were conducted. Human exposure was assessed using a tiered approach. Exposure to site-specific contaminants through the consumption of foodstuffs produced locally on the considered site was unlikely to be a health concern. However, as for inorganic arsenic, given the presence of highly contaminated zones, it was suggested that cereals should not be grown on certain plots. Two sites will be decontaminated because of the uptake of pollutants by crops (barley) or fresh water pollution caused by runoff. Spincourt is an example of the ignorance of soil contamination left behind by WWI in land-use planning. Further research is needed to assess these forgotten contaminations and sites and theirs related environmental risks