Sadly, this reminds me of St. Kilda - https://en.wikipedia.org/wiki/St_Kilda,_Scotland#Evacuation_... - a tiny, remote island north-west of Scotland - which was completely evacuated in 1930. The locals had long spread peat ash and seabird carcasses on their fields - not knowing that those were badly contaminated with lead and other old-fashioned pollutants.