However, recent evidence has demonstrated that very low levels of specific contaminants in wastewater, including hormones (from animal husbandry and residue from human hormonal contraception methods) and synthetic materials such as phthalates that mimic hormones in their action, can have an unpredictable adverse impact on the natural biota and potentially on humans if the water is re-used for drinking water.
Porén, hai probas recentes que demostran que se hai niveis moi baixos de contaminantes específicos nas augas residuais, incluíndo hormonas (procedentes da cría gandeira e residuos de hormonas contraceptivas humanas) ou de materiais sintéticos como ftalatos, que imitan na súa acción ás hormonas, poden ter un impacto adverso impredicible na biota natural e potencialmente nos humanos se a auga se reutiliza como auga potable.