Fate of Pharmaceutical Drugs and Metabolites in the Environment

Abstract

1. Issues/Problems In recent years, there have been global concerns about the emerging levels of abused drugs (cocaine, opioid, cannabinoid, amphetamine, lysergic diethylamide and hallucinogen) apart from pharmaceuticals, dyes, solvents, pesticides, heavy metals and chemicals from industrial wastes and direct dumping of other contaminants to the aquatic environment. The escalating levels of these pollutants have prompted the need for proper monitoring of their prevalence in order to stem its social and environmental impacts. New drugs are daily being introduced as the number of patents keeps increasing, and the pharmaceutical products for numerous therapeutic and commercial purposes keep escalating accordingly, reaching already the increasingly polluted environment. The inadvertent and purposeful discharges of pharmacologically active compounds via excreta remain underappreciated, yet their toxicological potency on the ecosystem has become a global issue. Environmental monitoring and risk assessments have shown the sewage treatment works as one of the potential routes through which the levels of consumption by a local population can be estimated. The exposure data of trends in their distribution, biodegradability, fate, toxicity and environmental assessment can safeguard aquatic and human environment by letting the appropriate authorities involved in fighting and controlling drug menace develop the desired approaches in controlling and effective monitoring of emerging pollution challenges. 2. Major Advances We reviewed the occurrence of bioactive metabolites, metabolism, measurement, transport routes in the aquatic environment and treatment processes with the available analytical methodologies in the literature.The major points are: 1. The literature showed the distribution of the plethora of trace drugs include abused drugs, which were as follows: cocaine, opioid, cannabinoid, amphetamine, lysergic diethylamide, hallucinogen and pharmaceuticals of many therapeutic classes of drugs: antibiotics, anti-inflammatory, anti-epileptics, antineoplastics, antidepressants, beta-blockers, β2-sympathomimetics, contraceptives, diagnostic contrast media, lipid regulators, preservatives, sunscreen agents and tranquilizers in the environment. They occurred in varying concentration and range from 10 to 8700 ng L−1 in sewage treatment works and 10–410 ng L−1 and stream at different locations. 2. The environmental analyses have shown that significant routes which the pharmaceutical drugs enter the aquatic environment are some domestic sewage systems from Italy, Belgium, Spain, Germany, the United States and the United Kingdom with 15 compounds detected from biweekly samplings from Nottingham sewage treatment work effluents, including ibuprofen, caffeine, lidocaine, cocaine, codeine, amphetamine, ecgonine methyl ester, benzoylecgonine, ephedrine, methadone, nicotine, 6-acetylmorphine, diacetylmorphine, diazepam and procaine. The mean concentrations, 19.2 ± 5.8, 15.2 ± 4.3, 13.6 ± 5.7, 9.1 ± 3.5, 8.2 ± 3.1, 5.1 ± 2.8, 4.7 ± 1.7 and 4.2 ± 1.7 ng L−1, were found, respectively. In Spain, 225 and 2307 ng L−1 of cocaine and benzoylecgonine in 5 sewage treatment work influents were higher compared to 47 ng L−1 of cocaine concentrations in effluent. The toxicity and extent of persistence may have potential effects on the environment after the sewage-sludge disposal to surface waters or landfills. 3. The reported hydrophilicity/lipophilicity properties of compounds allowed the chemical partitioning onto suspension in solution and biosolids with microbial degradation. The degradation possibilities of compounds include partial/complete degradation, mineralization or sorption to sludge, which is a repository of microorganism during sewage treatment work degradation processes. 4. The reported multistep extraction protocols reduced the matrix influences and improved recovery under stability of pH. The delivered extracts were very clean using several solid-phase extraction adsorbents as recent advances. The effluent concentrations ranged from 0.3 to 30.2 ng L−1 with percentage recoveries from 78.6 to 97.8%, using solid-phase extraction-gas chromatography-mass spectrometry in many studies. 5. The observed degree of removal of drugs from the influent and its relative concentrations were higher when compared to the effluent drug concentrations where about 10 times higher in the influent compared to the effluent were found. However, improved sampling strategies and recovery, new detection methodologies and reduction of matrix influences employed at the determination of most effluents have added new trends that will further improve the treatment capability and assessments of sewage treatment plants. KeywordsDrugsPharmaceuticalsWastewaterAnalysisEnvironment