Fate and Uptake of Pharmaceuticals in Soil–Plant Systems, Journal of Agricultural and Food Chemistry, January 2014

Following use by the patient, active pharmaceutical ingredients (APIs) and their metabolites are excreted to the sewerage system. They are then typically transported to a wastewater treatment works, where, depending on their molecular structure and physicochemical properties, they can be either degraded by biological treatment processes or released to the environment in effluents or sorb to sludge. The soil environment will therefore be exposed to APIs and their metabolites when sludge from treatment processes is applied to land as an agricultural fertilizer or when soil is irrigated with reclaimed wastewater effluent.
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Available data indicate that a range of API classes, including nonsteroidal anti-inflammatory drugs, antidepressants, anticonvulsants, and antibacterial agents do occur in soils in concentrations up to the low mg/kg level.
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Uptake into plants, especially edible crops, may represent an important exposure pathway of these chemicals into the food chain and thus present a risk to humans and livestock which feed on them.
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An important note for the future is that with the growing demand for alternative irrigation resources in water stressed regions and projected increases in the application of sewage sludge on land, pharmaceutical loadings in soil will inevitably increase.

When they determine limits, that is, how much anti-depressant is allowed in a carrot that a child eats, do they factor in the contribution of anti-depressant in all the other foods that child eats? I mean, I guess they do.