The problem with modern day sludge is that its quality is of much poorer standard than what was used a number of generations ago. In today's food cycle (and probably less so in developing countries), sewage is contaminated with heavy metals, medical residues, etc. some of which have the potential to be bioaccumulated into crops and animals.
The problem with modern day sludge is that its quality is of much poorer standard than what was used a number of generations ago. In today's food cycle (and probably less so in developing countries), sewage is contaminated with heavy metals, medical residues, etc. some of which have the potential to be bioaccumulated into crops and animals.