Household Disposal of Pharmaceuticals in Low-Income Settings: Practices, Health Hazards, and Research Needs

Round 1

Reviewer 1 Report

In this manuscript, a review of the current practices and pollution risks arising from the disposal of pharmaceuticals in low-income settings in Africa was reported. The manuscript is well written, but the authors must address some concerns before it is considered for publication.

1. This review is about Africa, could you please mention the year range that you covered in the introduction part?

2. To make this review complete, for MITIGATION & OUTLOOK part, could you please also put up some ideas/comments about how to remove the already existing pharmaceuticals in the environment? As far as I know, some methods/materials can be used to do so. For example (just as references):

1) Activated carbon absorption (doi:10.1007/s11356-012-1432-9)

2) Advanced oxidation processes (doi:10.1021/es9014629)

2) Linear and crosslinked polymers (doi:10.3389/fchem.2021.793870)

3) Covalent organic frameworks (doi:10.1016/j.chempr.2021.01.002)

 

You can add more information based on your knowledge and experience.

Author Response

In this manuscript, a review of the current practices and pollution risks arising from the disposal of pharmaceuticals in low-income settings in Africa was reported. The manuscript is well written, but the authors must address some concerns before it is considered for publication.

 

Author’s Response:

Thank you for your review, positive feedback, and additional comments. We were happy to deliver the revised version of our work.

 

1. This review is about Africa, could you please mention the year range that you covered in the introduction part?

 

Author’s Response:

This information was added in the first paragraph of the Materials and Methods by stating:

The search process covered the period 2000 to date (2022), but the first empirical studies were published from 2006 onwards. Since the search was limited to English scholarly databases, the study may have excluded studies published in non-English Languages.

 

2. To make this review complete, for MITIGATION & OUTLOOK part, could you please also put up some ideas/comments about how to remove the already existing pharmaceuticals in the environment? As far as I know, some methods/materials can be used to do so. For example (just as references):

 

1) Activated carbon absorption (doi:10.1007/s11356-012-1432-9)

 

2) Advanced oxidation processes (doi:10.1021/es9014629)

 

2) Linear and crosslinked polymers (doi:10.3389/fchem.2021.793870)

 

3) Covalent organic frameworks (doi:10.1016/j.chempr.2021.01.002)

 

Author’s Response:

Thanks for this suggestion. Please note that our paper elaborates on the disposal of pharmaceuticals in a low-income setting. Therefore, the advanced techniques postulated for pharmaceutical removal from the environment will not be available due to high costs. It is, therefore, pivotal to prevent the problem at its very source. We have stressed this in the revised section 5.5 by adding the below-given part and referring to the papers suggested by the Reviewer:

 

“One should note that in low-income settings, it is essential to mitigate and prevent pharmaceutical pollution at its very source because the methods of pharmaceutical removal from the environment, e.g., such as advanced oxidation processes, activated carbon absorption, or application of organic polymers, are high-cost processes due to the use of costly chemicals and increased energy consumption [127-130].”

 

[127] Kovalova, L.; Knappe, D.R.U.; Lehnberg, K.; Kazner, C.; Hollender, J. Removal of Highly Polar Micropollutants from Wastewater by Powdered Activated Carbon. Environ. Sci. Pollut. Res. Int. 2013, 20, 3607–3615.

 

[128] Hollender, J.; Zimmermann, S.G.; Koepke, S.; Krauss, M.; McArdell, C.S.; Ort, C.; Singer, H.; von Gunten, U.; Siegrist, H. Elimination of Organic Micropollutants in a Municipal Wastewater Treatment Plant Upgraded with a Full-Scale Post-Ozonation Followed by Sand Filtration. Environ. Sci. Technol. 2009, 43, 7862–7869.

 

[129] Zheng, Q.; Unruh, D.K.; Hutchins, K.M. Removal of the Micropollutants Propranolol Hydrochloride and 2-Naphthol from Water by Pyridine-Functionalized Polymers. Front. Chem. 2021, 9, 793870.

 

[130] Skorjanc, T.; Shetty, D.; Trabolsi, A. Pollutant Removal with Organic Macrocycle-Based Covalent Organic Polymers and Frameworks. Chem 2021, 7, 882–918.

 

 

You can add more information based on your knowledge and experience.

 

Author’s Response:

In the revised version, additional information on disposal practices in Europe and USA was added to the Introduction for comparison with discussed disposal methods in low-income settings. We have also added a list of methods for the final disposal of pharmaceuticals according to the WHO’s guideline. Appropriate references to these new parts were also added.

Reviewer 2 Report

The authors should elaborate more on the paper and organise it better, bearing in mind that it is a review paper. Once they include my suggestions they could be suggesting a possible publication.

 

Some points that should be added:

 

Summary of domestic pharmaceutical disposal practices in Europe and North America. 2.

2. Present the main techniques used to dispose of pharmaceutical products.

3. What characteristics do adsorbent and bioadsorbent materials need to have in order to remove pharmaceutical pollutants from water bodies.

4. What preventive treatments should be carried out on water bodies when the presence of this type of emerging pollutants is detected.

5. What are the variables to be controlled in the separation between adsorbate-adsorbent at an illustrative level.

6. From the thermodynamic point of view, what should be taken into account.

7. What previous mathematical models can be implemented to be successful in this type of implementation when removing pharmaceutical pollutants?

 

 

Author Response

The authors should elaborate more on the paper and organise it better, bearing in mind that it is a review paper. Once they include my suggestions they could be suggesting a possible publication.

Author’s Response:

Thank you for reviewing our manuscript and providing feedback. We have revised our paper and provided the response to each comment below.

1. Summary of domestic pharmaceutical disposal practices in Europe and North America.

 

Author’s Response:

We have added a paragraph in the Introduction to elaborate on the disposal of pharmaceuticals in the USA and European countries. This paragraph states:

 

“The USA and various European countries adopted the disposal of unused or expired pharmaceuticals through take-back locations, which are available in retail, hospital, clinical pharmacies, or law enforcement facilities [30,31]. Periodically, additional temporary take-back sites are established for annual events such as National Drug Prescription Day [31]. Moreover, if the take-back option is not readily available, the FDA has published a list of pharmaceuticals (encompassing 15 active ingredients) that can be flushed down the sink or toilet. The medicines on this list include those that can result in death from one dose if inappropriately taken and sough-after their misuse/and/or abuse potential [32]. As assessed, pharmaceutical ingredients on the FDA's "flush list" present negligible risk through the ingestion of water and fish [33].”

 

 

[30] Mitkidis, K.; Obolevich, V.; Chrysochou, P.; Mitkidis, P. Harmonisation of Pharmaceutical Take-Back Systems in the EU. Eur. J. Health Law 2021, 1–27.

 

[31] Drug Disposal: Drug Take Back Locations Available online: https://www.fda.gov/drugs/disposal-unused-medicines-what-you-should-know/drug-disposal-drug-take-back-locations (accessed on 13 January 2023).

 

[32] Drug Disposal: FDA’s Flush List for Certain Medicines Available online: https://www.fda.gov/drugs/disposal-unused-medicines-what-you-should-know/drug-disposal-fdas-flush-list-certain-medicines (accessed on 13 January 2023).

 

[33] Khan, U.; Bloom, R.A.; Nicell, J.A.; Laurenson, J.P. Risks Associated with the Environmental Release of Pharmaceuticals on the U.S. Food and Drug Administration “Flush List.” Sci. Total Environ. 2017, 609, 1023–1040.

 

2. Present the main techniques used to dispose of pharmaceutical products.

 

Author’s Response:

We have added this information and referred to WHO’s guideline. This part was added to the Introduction:

 

“Methods of final disposal of pharmaceuticals can differ depending on the type and form of medicines. World Health Organization provides the guideline on these methods that encompass high (>1200°C) or medium (≥850°C) temperature incineration, immobilization by waste encapsulation or inertization, landfill disposal through highly engineered sanitary landfill, fast-flowing watercourse, and chemical decomposition [34]. Disposal of pharmaceuticals through a sewer, open non-engineered dump, or burning in open containers is considered the last resort method for some medicines [34].”

 

[34] World Health Organization; Churches’ Action for Health of the World Council of Churches; ECHO International Health Services Ltd; International Committee of the Red Cross; International Federation of Red Cross and Red Crescent Societies; International Pharmaceutical Association; International Solid Waste Association; Médecins sans frontières (Association); UNHCR; Oxfam; et al. Guidelines for Safe Disposal of Unwanted Pharmaceuticals in and after Emergencies; World Health Organization, 1999;

 

3. What characteristics do adsorbent and bioadsorbent materials need to have in order to remove pharmaceutical pollutants from water bodies.
4. What preventive treatments should be carried out on water bodies when the presence of this type of emerging pollutants is detected.

 

Author’s Response:

Thank you for this comment. Since our review focuses on the household disposal of pharmaceuticals in low-income settings, removing pharmaceuticals from the water bodies is currently not an available option. In general, there are various methods developed for the potential removal of these contaminants, but they are expensive and require high energy input. For this reason, we have added the following part to section 5.5.:

 

“One should note that in low-income settings, it is essential to mitigate and prevent pharmaceutical pollution at its very source because the methods of pharmaceutical removal from the environment, e.g., such as advanced oxidation processes, activated carbon absorption, or application of organic polymers, are high-cost processes due to the use of costly chemicals and increased energy consumption [127-130].”

 

[127] Kovalova, L.; Knappe, D.R.U.; Lehnberg, K.; Kazner, C.; Hollender, J. Removal of Highly Polar Micropollutants from Wastewater by Powdered Activated Carbon. Environ. Sci. Pollut. Res. Int. 2013, 20, 3607–3615.

 

[128] Hollender, J.; Zimmermann, S.G.; Koepke, S.; Krauss, M.; McArdell, C.S.; Ort, C.; Singer, H.; von Gunten, U.; Siegrist, H. Elimination of Organic Micropollutants in a Municipal Wastewater Treatment Plant Upgraded with a Full-Scale Post-Ozonation Followed by Sand Filtration. Environ. Sci. Technol. 2009, 43, 7862–7869.

 

[129] Zheng, Q.; Unruh, D.K.; Hutchins, K.M. Removal of the Micropollutants Propranolol Hydrochloride and 2-Naphthol from Water by Pyridine-Functionalized Polymers. Front. Chem. 2021, 9, 793870.

 

[130] Skorjanc, T.; Shetty, D.; Trabolsi, A. Pollutant Removal with Organic Macrocycle-Based Covalent Organic Polymers and Frameworks. Chem 2021, 7, 882–918.

5. What are the variables to be controlled in the separation between adsorbate-adsorbent at an illustrative level.

Author’s Response:

Thank you for this comment, although we believe that issues related to the separation between adsorbate-adsorbent do not really correspond to the aims and focus of our paper. This is because the paper does not focus on adsorption of pharmaceuticals from aqueous solutions, but rather disposal at household levels in their various forms. Here, we provide the first review of household disposal of pharmaceuticals with potential implications for the environment, including water resources.

6. From the thermodynamic point of view, what should be taken into account.

 

Author’s Response:

Thank you for this comment, although we believe that this issue does not really correspond to the aims and focus of our paper. As for the previous comment, the present paper does not address the adsorption of pharmaceuticals from aqueous media – hence the concept of adsorption thermodynamics is not applicable. In the present paper, we provide the first review of household disposal of pharmaceuticals with potential implications for the environment, including water resources.

7. What previous mathematical models can be implemented to be successful in this type of implementation when removing pharmaceutical pollutants?

 

Author’s Response:

We considered the comment, but we are unclear on what aspect the mathematical modelling refers to – it seems the reviewer refers to removal of pharmaceuticals from aqueous systems where various isotherm and kinetic models apply. As explained above, the present paper does not address adsorption or removal of pharmaceuticals, but rather their disposal at household level. The present paper focuses on the disposal of pharmaceuticals in low-income settings and how that, in turn, contributes to the pollution of groundwater resources via the migration of water and contaminants. We are unaware of mathematical models that have been implemented to predict the disposal of pharmaceuticals in various. The modelling studies on the removal of pharmaceuticals are limited to water and wastewater treatment, which are beyond the scope of the present paper. In our view, the only aspect that could entail the use of models is the contaminant migration and fate of the pit latrine-groundwater systems.

 

To reflect this, we revised the section on future research relating to tracer studies as follows:

 

‘Research on tracer studies can also be linked to modelling of the transport, behavior, and fate of the various contaminants in the pit latrine-groundwater continuum. Such models should be based on the source-pathway-receptor-impact-mitigation (SPRIM) contin-uum concept [124]. Yet, in the case of emerging contaminants, such models are still lacking, hence, need to be developed, validated, and then applied [124]. This aspect is discussed in detail in an Editorial Perspective to the present Special Issue by the first author [124].’.

 

The lack of models accounting for emerging contaminants in the source-pathway-receptor-impact-mitigation continuum is discussed in another paper under revision in the present special issue entitled:

 

[124] Gwenzi W. 2022. Closing blank and blind spots in research on emerging contaminants: The Source–Pathway–Receptor–Impact–Mitigation (SPRIM) Continuum as an Organizing Framework. Guest Editor’s Editorial Perspective to a Special Issue entitled, ‘Emerging Organic Contaminants in Aquatic Systems: A Focus on the Source–Pathway–Receptor–Impact–Mitigation Continuum.’, Water (MDPI, Basel, Switzerland), xx: xx-xx. In revision.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The brief is now in shape for publication.