Disposal of Pharmaceuticuals and Aquatic Contamination
Disposal of Pharmaceuticuals and Aquatic Contamination
Pharmaceuticals are produced and used in increasingly large volumes every year. With this growth comes concern about the fate and effects of these compounds in the environment. The discovery of pharmaceuticals in the aquatic environment has stimulated research in the last decade. A wide range of pharmaceuticals has been found in fresh and marine waters, and it has recently been shown that even in small quantities, some of these compounds have the potential to cause harm to aquatic life. The primary pathway into the environment is the use and disposal of medicines; although much of the research in the area currently focuses on the removal of pharmaceuticals during sewage treatment processes, disposal via household waste might be a significant pathway requiring further research. To investigate the household disposal of unused and expired pharmaceuticals as a source of pharmaceutical compounds in the environment, we carried out a survey and interviewed members of 400 households, predominantly from southeastern England. We used the information on when and how they disposed of unfinished pharmaceuticals to construct a conceptual model to assess the pathways of human pharmaceuticals into the environment. The model demonstrated that disposal of unused pharmaceuticals, either by household waste or via the sink or toilet, may be a prominent route that requires greater attention. Key words: drugs, prescriptions, risk assessment, survey, wastewater treatment.
The presence and potential adverse effects of pharmaceuticals in the aquatic environment have begun to receive increasing attention in the popular and scientific press in recent years. This increase is largely a result of a number of scientific papers published in the 1990s that reported trace levels of pharmaceuticals detected in environmental samples, including sewage effluent, surface water, groundwater, and even drinking water, mainly in European countries (Buser et al. 1998; Daughton and Ternes 1999; Halling-Sorensen et al. 1998; Heberer 2002; Jones et al. 2001; Kolpin et al. 2002; Ternes 1998; Ternes et al. 1999). The existence of pharmaceuticals in the U.K. aquatic environment has been established, but the extent of their distribution and the possible ecotoxicologic consequences associated with their presence are less clear. Pharmaceuticals are produced and used in very large volumes, and their use and diversity are increasing every year. Estimates based on the number of prescriptions issued suggest that around 100 tons of drugs were prescribed in Germany in 1995 (Ternes 1998). In the United Kingdom in 2000, use exceeded > 10 tons/year for each of the top 25 compounds, and the amount of the top three compounds prescribed [acetaminophen (paracetamol), metformin hydrochloride, and ibuprofen] was > 100 tons/year each (Jones et al. 2002). Recent research has shown that these compounds could have a negative effect on the aquatic environment (Jones et al. 2003). Observed environmental effects are limited mainly to the feminizing activity of endocrine-disrupting compounds such as the synthetic hormone 17α-ethinyl estradiol on fish near wastewater treatment works (WWTW) outfalls (Jobling et al. 1998; Länge et al. 2001; Routledge et al. 1998). Other concerns include the development of antibacterial resistance either in or near WWTWs (Schwartz et al. 2002) or in the environment as a consequence of veterinary drug use (Petersen et al. 2002). Detection of these negative effects in the environment is difficult; although in vivo and in vitro laboratory tests generally show that the toxic effects of these compounds are not seen at the low levels currently detected in the environment, the possibility of variations in sensitivity, chronic exposure, and mixture effects such as concentration addition and synergism (Altenburger et al. 2004; Cleuvers 2004; Richards et al. 2004) mean that other negative effects cannot be ruled out. As a result, risk assessment guidance has been developed to predict the environmental impact caused by new pharmaceuticals [Bound and Voulvoulis 2004; European Agency for the Evaluation of Medicinal Products (EMEA) 2005; U.S. Food and Drug Administration (FDA) 1998].
There are two main routes for pharmaceuticals to enter the environment. The first is via the effluent from WWTWs after excretion from the body (Figure 1). After administration, a significant proportion of a pharmaceutical may pass through the body unmetabolized. The degree to which a compound is changed in the body depends on its structure and mechanism of action. The β-blocker nadolol may pass through the human body completely unmodified (RxList 2005a). In contrast, only 3% of the parent form of the antiepileptic carbamazepine is excreted unchanged in the urine (RxList 2005b); the rest may be conjugated or hydroxylated and also released in the feces. Release via this pathway is governed by the pharmacology of the drug and the efficiency of the WWTW. Excretion rates of many pharmaceuticals, such as those shown in Table 1 , can be found in both medical (Martindale 1993) and environmental literature (Calamari et al. 2003; Jjemba, in press). The exact rates also depend on the dosage and the physiology of the individual.
(Enlarge Image)
Pathways of drug fate from domestic households to the environment
Data on WWTW removal efficiencies are sparse and are largely dependent on the facilities at individual WWTWs and on variables such as local rainfall and temperature ( Table 2 ). For example, only 9% of diclofenac was found to be removed by biologic filtration, whereas 75% was removed by activated sludge treatment (Stumpf et al. 1999). Because these data are required by the draft European Union guidelines on risk assessment (EMEA 2005), there will presumably be an increase in research in this area.
The second route by which pharmaceuticals can enter the environment is by the disposal of out-of-date or unwanted medicines, which may occur via the sink/toilet or in household waste that is then taken to landfill sites (Figure 1). Entry into the environment by this route is dependent on the habits of the patient and the efficiency of prescription practices leading to fewer unfinished prescriptions. Discarded pharmaceuticals are defined in the United Kingdom by the Controlled Waste Regulations 1992 [Her Majesty's Stationery Office (HMSO) 1992] as clinical waste and as such are controlled by the Special Waste Regulations 1996 (HMSO 1996). According to this legislation, such waste may be disposed of in landfill sites designed to accommodate hazardous waste, or it may be incinerated. However, once dispensed to or purchased by a member of the public, any unwanted pharmaceutical products are classified as household waste, and their disposal is not subject to any controls. Manufacturer packaging usually recommends disposal by returning to the pharmacist; however, disposal via the sink/toilet or in normal household waste is common. Pharmaceuticals in landfill sites are subject to biologic degradation processes, but some may persist and even leach into surrounding groundwater and rivers (Ahel et al. 1998; Holm et al. 1995; Schwarzbauer et al. 2002).
An investigation into the disposal habits of the American public found that only 1.4% of the people they surveyed returned unused medication to the pharmacy, whereas 54% threw them away and 35.4% disposed of them in the sink/toilet (Kuspis and Krenzelok 1996). These methods of disposal result from U.S. Drug Enforcement Administration regulations that strictly control the transfer of drugs and controlled substances. It is possible for some institutions to return unwanted drugs via organizations affiliated with the Returns Industry Association, a group of licensed "reverse distributors" that offer a return and disposal service (Daughton 2003b). Although regulations vary among U.S. states, most pharmacies cannot accept returns from patients. Measures to allow the return of unused medication from long-term care facilities have been passed or are being considered in some states. Developments in legislation are listed on the National Conference of State Legislatures website (NCSL 2005). Some states will also allow the redistribution of drugs within their expiration date, although they do not permit the return of drugs by private individuals. This service is therefore limited largely to medicines that never leave pharmacies and care facilities.
A source of concern is that, at the pharmacies questioned, 68% of unreturnable medicines were disposed of in nonhazardous waste or via the drain. Traditionally, disposal advice to consumers has been limited to flushing down the toilet or, in some cases, burning or grinding and discarding in household waste (Pray and Pray 2004), but emerging environmental concerns mean that this is sometimes modified (Daughton 2003b). People are first advised to check whether local pharmacies or doctors are able to receive returns or whether hazardous waste facilities exist in the area. As a last resort, disposal in household waste is deemed to be less harmful than disposal via the sewage system (Boehringer 2004). A study by Braybrook et al. (1999), designed to examine ways to streamline the prescription process in order to reduce costs, looked at some of the reasons people gave for returning unused pharmaceuticals to the pharmacy. The most common reason was a change of medication. Most items (80%) were returned within a year of their prescription date, but some people returned the medicines only after the infrequent removal of unwanted items that have built up over time, with some products being returned 13 years after they were dispensed.
The aim of the present study was to identify and assess the significance of the different pathways of pharmaceuticals from the household to the environment. Knowledge of the motivation behind different disposal methods is useful in the management of the release of pharmaceuticals in the environment and in the assessment of the associated risk. This project aimed to demonstrate the possible importance of household disposal of unused medicines as a pathway into the aquatic environment.
Pharmaceuticals are produced and used in increasingly large volumes every year. With this growth comes concern about the fate and effects of these compounds in the environment. The discovery of pharmaceuticals in the aquatic environment has stimulated research in the last decade. A wide range of pharmaceuticals has been found in fresh and marine waters, and it has recently been shown that even in small quantities, some of these compounds have the potential to cause harm to aquatic life. The primary pathway into the environment is the use and disposal of medicines; although much of the research in the area currently focuses on the removal of pharmaceuticals during sewage treatment processes, disposal via household waste might be a significant pathway requiring further research. To investigate the household disposal of unused and expired pharmaceuticals as a source of pharmaceutical compounds in the environment, we carried out a survey and interviewed members of 400 households, predominantly from southeastern England. We used the information on when and how they disposed of unfinished pharmaceuticals to construct a conceptual model to assess the pathways of human pharmaceuticals into the environment. The model demonstrated that disposal of unused pharmaceuticals, either by household waste or via the sink or toilet, may be a prominent route that requires greater attention. Key words: drugs, prescriptions, risk assessment, survey, wastewater treatment.
The presence and potential adverse effects of pharmaceuticals in the aquatic environment have begun to receive increasing attention in the popular and scientific press in recent years. This increase is largely a result of a number of scientific papers published in the 1990s that reported trace levels of pharmaceuticals detected in environmental samples, including sewage effluent, surface water, groundwater, and even drinking water, mainly in European countries (Buser et al. 1998; Daughton and Ternes 1999; Halling-Sorensen et al. 1998; Heberer 2002; Jones et al. 2001; Kolpin et al. 2002; Ternes 1998; Ternes et al. 1999). The existence of pharmaceuticals in the U.K. aquatic environment has been established, but the extent of their distribution and the possible ecotoxicologic consequences associated with their presence are less clear. Pharmaceuticals are produced and used in very large volumes, and their use and diversity are increasing every year. Estimates based on the number of prescriptions issued suggest that around 100 tons of drugs were prescribed in Germany in 1995 (Ternes 1998). In the United Kingdom in 2000, use exceeded > 10 tons/year for each of the top 25 compounds, and the amount of the top three compounds prescribed [acetaminophen (paracetamol), metformin hydrochloride, and ibuprofen] was > 100 tons/year each (Jones et al. 2002). Recent research has shown that these compounds could have a negative effect on the aquatic environment (Jones et al. 2003). Observed environmental effects are limited mainly to the feminizing activity of endocrine-disrupting compounds such as the synthetic hormone 17α-ethinyl estradiol on fish near wastewater treatment works (WWTW) outfalls (Jobling et al. 1998; Länge et al. 2001; Routledge et al. 1998). Other concerns include the development of antibacterial resistance either in or near WWTWs (Schwartz et al. 2002) or in the environment as a consequence of veterinary drug use (Petersen et al. 2002). Detection of these negative effects in the environment is difficult; although in vivo and in vitro laboratory tests generally show that the toxic effects of these compounds are not seen at the low levels currently detected in the environment, the possibility of variations in sensitivity, chronic exposure, and mixture effects such as concentration addition and synergism (Altenburger et al. 2004; Cleuvers 2004; Richards et al. 2004) mean that other negative effects cannot be ruled out. As a result, risk assessment guidance has been developed to predict the environmental impact caused by new pharmaceuticals [Bound and Voulvoulis 2004; European Agency for the Evaluation of Medicinal Products (EMEA) 2005; U.S. Food and Drug Administration (FDA) 1998].
There are two main routes for pharmaceuticals to enter the environment. The first is via the effluent from WWTWs after excretion from the body (Figure 1). After administration, a significant proportion of a pharmaceutical may pass through the body unmetabolized. The degree to which a compound is changed in the body depends on its structure and mechanism of action. The β-blocker nadolol may pass through the human body completely unmodified (RxList 2005a). In contrast, only 3% of the parent form of the antiepileptic carbamazepine is excreted unchanged in the urine (RxList 2005b); the rest may be conjugated or hydroxylated and also released in the feces. Release via this pathway is governed by the pharmacology of the drug and the efficiency of the WWTW. Excretion rates of many pharmaceuticals, such as those shown in Table 1 , can be found in both medical (Martindale 1993) and environmental literature (Calamari et al. 2003; Jjemba, in press). The exact rates also depend on the dosage and the physiology of the individual.
(Enlarge Image)
Pathways of drug fate from domestic households to the environment
Data on WWTW removal efficiencies are sparse and are largely dependent on the facilities at individual WWTWs and on variables such as local rainfall and temperature ( Table 2 ). For example, only 9% of diclofenac was found to be removed by biologic filtration, whereas 75% was removed by activated sludge treatment (Stumpf et al. 1999). Because these data are required by the draft European Union guidelines on risk assessment (EMEA 2005), there will presumably be an increase in research in this area.
The second route by which pharmaceuticals can enter the environment is by the disposal of out-of-date or unwanted medicines, which may occur via the sink/toilet or in household waste that is then taken to landfill sites (Figure 1). Entry into the environment by this route is dependent on the habits of the patient and the efficiency of prescription practices leading to fewer unfinished prescriptions. Discarded pharmaceuticals are defined in the United Kingdom by the Controlled Waste Regulations 1992 [Her Majesty's Stationery Office (HMSO) 1992] as clinical waste and as such are controlled by the Special Waste Regulations 1996 (HMSO 1996). According to this legislation, such waste may be disposed of in landfill sites designed to accommodate hazardous waste, or it may be incinerated. However, once dispensed to or purchased by a member of the public, any unwanted pharmaceutical products are classified as household waste, and their disposal is not subject to any controls. Manufacturer packaging usually recommends disposal by returning to the pharmacist; however, disposal via the sink/toilet or in normal household waste is common. Pharmaceuticals in landfill sites are subject to biologic degradation processes, but some may persist and even leach into surrounding groundwater and rivers (Ahel et al. 1998; Holm et al. 1995; Schwarzbauer et al. 2002).
An investigation into the disposal habits of the American public found that only 1.4% of the people they surveyed returned unused medication to the pharmacy, whereas 54% threw them away and 35.4% disposed of them in the sink/toilet (Kuspis and Krenzelok 1996). These methods of disposal result from U.S. Drug Enforcement Administration regulations that strictly control the transfer of drugs and controlled substances. It is possible for some institutions to return unwanted drugs via organizations affiliated with the Returns Industry Association, a group of licensed "reverse distributors" that offer a return and disposal service (Daughton 2003b). Although regulations vary among U.S. states, most pharmacies cannot accept returns from patients. Measures to allow the return of unused medication from long-term care facilities have been passed or are being considered in some states. Developments in legislation are listed on the National Conference of State Legislatures website (NCSL 2005). Some states will also allow the redistribution of drugs within their expiration date, although they do not permit the return of drugs by private individuals. This service is therefore limited largely to medicines that never leave pharmacies and care facilities.
A source of concern is that, at the pharmacies questioned, 68% of unreturnable medicines were disposed of in nonhazardous waste or via the drain. Traditionally, disposal advice to consumers has been limited to flushing down the toilet or, in some cases, burning or grinding and discarding in household waste (Pray and Pray 2004), but emerging environmental concerns mean that this is sometimes modified (Daughton 2003b). People are first advised to check whether local pharmacies or doctors are able to receive returns or whether hazardous waste facilities exist in the area. As a last resort, disposal in household waste is deemed to be less harmful than disposal via the sewage system (Boehringer 2004). A study by Braybrook et al. (1999), designed to examine ways to streamline the prescription process in order to reduce costs, looked at some of the reasons people gave for returning unused pharmaceuticals to the pharmacy. The most common reason was a change of medication. Most items (80%) were returned within a year of their prescription date, but some people returned the medicines only after the infrequent removal of unwanted items that have built up over time, with some products being returned 13 years after they were dispensed.
The aim of the present study was to identify and assess the significance of the different pathways of pharmaceuticals from the household to the environment. Knowledge of the motivation behind different disposal methods is useful in the management of the release of pharmaceuticals in the environment and in the assessment of the associated risk. This project aimed to demonstrate the possible importance of household disposal of unused medicines as a pathway into the aquatic environment.
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