Laboratory Testing of Sulfamethoxazole and its Metabolite Acetyl‐Sulfamethoxazole in Soil

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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.

Section: Test Substances and Soils Under Studymentioning

confidence: 99%

“…The microbial activity was determined by substrate induced respiration (SIR) measurements [22]. Therefore, the oxygen demands were 0.9 and 0.4 mg O2 100 g -1 dry soil h -1 , respectively, revealing microbially active soil samples [15].…”

Section: Test Substances and Soils Under Studymentioning

confidence: 99%

Metabolic Fate Modeling of Selected Human Pharmaceuticals in Soils

Richter

Kullmer

Kreuzig

2007

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“…Reference standards were prepared by dissolving each test substance in an appropriate solvent. The analytical procedures were described in detail by Höltge and Kreuzig [12], Kreuzig and Höltge [14] and Kreuzig et al [23]. The transformation tests in reference manures were conducted in a laboratory batch system traced back to the OECD Guideline 304 A [39] and described in detail by Kreuzig et al [40].…”

Section: Test Substances and Laboratory Batch Systemsmentioning

confidence: 99%

“…Due to substantially different conditions of digestion towers and manure tanks, i.e., mode of operation, dwell periods, temperatures, sources of materials, microbial communities etc., information about the fate of biocides in digested sludges can be hardly transferred to liquid manures. This was clearly shown by transformation tests of different 14 Clabeled test substances, e.g., sulfamethoxazole and acetyl-sulfamethoxazole [12]. Several fate monitoring studies applying liquid tank manures have been already conducted [13][14][15][16].…”

Section: Introductionmentioning

confidence: 97%

The Reference Manure Concept for Transformation Tests of Veterinary Medicines and Biocides in Liquid Manure

Kreuzig

2010

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Veterinary medicines and biocides are frequently applied in animal houses of livestock husbandry. Due to these application patterns, they reach liquid manure. So far these substances are not transformed during manure storage, they enter soil by the application of manure as organic fertilizer. Therefore, biodegradability of veterinary medicines and biocides in manure is in the focus of regulatory procedures of environmental risk assessment. Since the representative and reproducible sampling of manures from high volume tanks is considered impossible due to high matrix variabilities, the reference manure concept was developed to utilize liquid bovine and pig manures for reproducible laboratory testing. Accordingly, excrement samples of cattle and pigs individually kept at experimental and conventional animal houses were taken. Tap water was added to matrix characterized excrements in order to prepare bovine and pig reference manures of 10 and 5% dry substance contents, respectively. Subsequently, the long-term transformation of selected 14 C-labeled test substances was investigated under strictly anaerobic conditions. The application of different batches of bovine or pig reference manures indicated that extrapolation of transformation rates within the same animal species was possible. However, results cannot be transferred from bovine to pig manure because of substance specific interactions with the different manure matrices. The dependency of metabolic dynamics on different dry substance contents (2.5, 5, 10%) was additionally investigated in both manure matrices. These tests clearly showed that the dry substance content of the reference manure is one of the most relevant factors affecting the transformation of veterinary medicines and biocides. In contrast to highly variable tank manures, the reference manure concept allows for the exact adjustment of this parameter to guarantee reproducible laboratory testing.

“…Then, the flasks were incubated at 20 € 18C in the dark in intervals up to 102 days. Details of the analytical processing were described by Kreuzig and Höltge [1] and Höltge and Kreuzig [28]. For quality assurance, mass balances were set up and selected batches were conducted in duplicate.…”

Section: Degradation Tests In Pig Manurementioning

confidence: 99%

Fate of the Benzimidazole Antiparasitics Flubendazole and Fenbendazole in Manure and Manured Soils

Kreuzig¹,

Blümlein

Höltge

2007

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The fate of flubendazole and fenbendazole in manure and manured soils was investigated under laboratory and field conditions. In pig manure, both 14 C-labeled benzimidazoles disappeared slowly. After a 102 day incubation period, extractable fractions contained 72% flubendazole or 80% fenbendazole of the radioactivity initially applied. The latter was accompanied by 4% of the corresponding metabolite fenbendazole-sulfoxide. Non-extractable residues amounted to 24 and 13%, respectively. On this basis, test manures with 7 day aged benzimidazole residues were prepared. Mobility tendencies differed for clay and sand soils as well as for standard and test-manure application. Regarding K OC A 1100 L/kg, however, criteria for potential leachers were not fulfilled. The metabolic fate of flubendazole was predominated by the occurrence of the parent compound while fenbendazole was accompanied by fenbendazole-sulfoxide. In clay soil samples after standard application, DT 50 values were 174 and 54 days, respectively. Mineralization and formation of non-extractable residues were of minor relevance. For fenbendazole, these processes were intensified after test-manure application. Due to enhanced formation of fenbendazole-sulfoxide, fenbendazolesulfone, and non-extractable residues, DT 50 thus dropped to 9 days. Similar mobility and degradability tendencies were also found under field conditions. In the sand soil, however, the metabolic dynamics decelerated due to its lower microbial activity.