Metabolic Fate Modeling of Selected Human Pharmaceuticals in Soils

Abstract

Dedicated to Prof. Dr. mult. Dr. h. c. Müfit Bahadir on the occasion of his 60 th birthdayAs a consequence of human pharmaceuticals being found in surface, ground and drinking water, there is growing interest in their fate and behavior in soil environments. Therefore, laboratory tests on the degradation of the 14 C-labeled model substances ibuprofen and diazepam were performed in two different soils. Based on the results of the laboratory-batch experiments, metabolic fate models have been devised using model discriminating techniques based on likelihood tests for nested models. Although, the data for ibuprofen fit well into the frame of linear compartment theory, the diazepam data show pronounced nonlinearities. The kinetic behavior of both pharmaceuticals in soil is characterized by the participation of microbial processes in the formation of non-extractable residues and by low degradation rates out of the non-extractable fractions. An accumulation of those non-extractable residues may occur in soils under simulated multiple contaminations.

Sorption and persistence of wastewater-borne psychoactive and antilipidemic drugs in soils

“…The similarity between sterilized and nonsterile soils also suggested a lack of microbial involvement in the dissipation of diazepam in the BC soil. Similar to our finding, diazepam was demonstrated to be refractory to biodegradation in two previous studies (Richter et al 2007;Redshaw et al 2008).…”

“…Nearly 93% of sulfamethoxazole became nonextractable after 102 days incubation in soil (Heise et al 2006). Similarly, more than 15% of diazepam was found to be nonextractable after 55 days of incubation in soils (Richter et al 2007). Furthermore, the dissipation curve of carbamazepine in the sterilized BC soil followed a very similar pattern to that in the nonsterile BC soil, suggesting that microbial transformations did not contribute to the observed loss.…”

“…This loss was likely due to the formation nonextractable residues. For example, other studies using radioisotope labeling techniques showed the widespread occurrence of nonextractable or bound residues of pharmaceutical and personal care products in soils or sediments (Al-Rajab et al 2009;Heise et al 2006;Höltge and Kreuzig 2007;Richter et al 2007). Nearly 93% of sulfamethoxazole became nonextractable after 102 days incubation in soil (Heise et al 2006).…”

Advances in the Development of Procedures to Establish the Toxicity of Non-Extractable Residues (NER) in Soil. LRI-ECO25

“…Some information with regard to the formation of NER for specific pharmaceuticals and personal care products was found in Eschenbach (2013), who summarized data on various pharmaceuticals found in open literature. This list was amended with further information found during a quick sweep of literature in Scopus, which resulted in papers by Heise et al (2006), Kreuzig et al (2007) and Richter et al (2007). The resulting information is summarized in Table 5.…”