Typical levels of the natural oestrogens 17a-oestradiol, 17ß-oestradiol and estrone reach hundreds or even thousands of micrograms per kilogram dry weight, the review notes. After land spreading of manure, concentrations of up 3,500 nanograms per litre of oestradiol have been reported in run-off. Oestradiol concentrations of only 30ng/l can cause effects in fish.
The review notes that the US Geological Survey reported oestradiol levels of up to 200ng/l of oestradiol and 120ng/l of oestrone in streams polluted by animal manures.
Another US study found a strong correlation between faecal coliform concentrations and oestradiol in groundwaters from a livestock farming area of Arkansas. Oestradiol levels in the water ranged from 6-66ng/l.