Microplastics in drinking water and child stool

Micro- and nanoplastics (MnP) are omnipresent in the natural and built environment. Our groups have evidenced their presence in water, air and food, including outdoor and indoor environments. 

Plastic bottles piled up on the seashore

A public health priority:

Micro- and nanoplastics (MnPs) are omnipresent in the natural and built environment. Our team has evidenced their presence in water, air and food, including outdoor and indoor environments. We are developing protocols for the standardised extraction and quantification of MnPs from environmental samples as well as human tissues including brain, stool, spinal fluid, and blood. While there has been remarkable progress in identifying MnPs pollution sources, their transport mechanisms and hotspots of accumulation and exposures, uptake in food webs and consequences for environmental functioning and health, the health effects of MnPs have not been explored epidemiologically or for childhood diseases. Cellular- level studies indicate multiple possible mechanistic pathways and influences on organs. MnP have been shown, for instance, to cause gut inflammation and their absorption into the body, which likely worsens the MnP impact, and increases in the presence of gut inflammation. Diarrhoea can involve inflammation in the gut and therefore may be exacerbated by MnPs and in particular the leaching of their additives, including endocrine disrupting substances such as Bisphenol A, phthalates, brominated flame retardants and others. There is also limited evidence that protective microbiome organisms may either be harmed or influence the biodegradation of MnP, both with competing effects on the risks of MnPs.

Based on our observational studies of the presence of plastic waste in the environment, and pilot studies investigating MnP in children’s drinking water and stool, microplastic exposure through food, water, and air is expected to be high in Mali. Common conditions such as diarrhoea will therefore exacerbate the potential harms of MnPs increasing inequalities. We plan on conducting a number of studies to provide important evidence on the potential effects of MnPs (and their additives) exposure and uptake on child health to help prioritise further research and intervention policy.

We have secured funding for and conducted a range of studies developing the required experimental analytical techniques and protocols summarised below, that now bring us into the unique position to seek additional funding for further epidemiological work.

Research Project Team Leads  

University of Birmingham (UOB): Dr S Manaseki-Holland and Professor S Krause 

Team members 

University of Birmingham (UOB)-  Dr Liam Kelleher, Professor I LynchDr Evans AsamaneProfessor N Thomas

University of Science Technique and Technology, Bamako (USTTB): Mr Youssouf Diarra, Professor O Koita, Professor O Toure, Dr Cheick Sidibe,  Mr Modibo Telly 

Studies/activities led by our UOB Geography Department laboratories and Institute of Applied Health Sciences thus far: 

Activity 1: Development of MnP extraction and identification protocols for environmental media (water, air (passive and active sampling systems), food sources, soil, plant material, animal, and human tissue (including stool)). Thus we have established analytical methods and libraries for MnP characterization.

Activity 2: Scoping scientific review of MnP and human health outcomes with specific focus on exacerbation of inflammatory disease, currently under peer-review for journal publication.

Based on preliminary studies in Mali:

1. Mapping of plastic use/garbage in households in Urban and Rural Mali; 2 nested studies, first, funded - Institute for Global Innovation, University of Birmingham; second, funded by UKRI Medical Research Council.

Research questions: How are plastic items used in the household e.g. utensils or containers related to eating or drinking, and the extent of plastic waste in the household compounds? What are the socioeconomic variables associated with the extent of such exposure?


Nested study 1: As a nested study, we explored the above research questions in 280 randomly selected houses in 3 villages and 2 urban Bamako communities. A questionnaire was used to collect data on use of common plastic items in the household. Observation of the waste areas (rubbish pile/container) as well as deposits around the compound in the household was done to estimate the presence of plastic in their rubbish/household waste. The questionnaire and observational data are coded to enable a comparison between urban and rural households, or by other characteristics such as the education level.

Nested study 2: In a large RCT MaaCiwara study similar observations are being made about plastics disposal – data collection in progress.

Preliminary results:  100% of the surveyed families used plastic items for kitchen or eating as well as other household use in nested study 1.

In nested studies 1 and 2: All households had plastic waste around their compounds; the measure of waste around the compound and in the waste pile/bin is currently being coded for quantification.

2. Identification of MnP in stools of exposure and their association with diarrhoea, growth, and development of children in Mali and first explorative analysis of exposure routes and possible indication for association with diarrhoea, growth, and development of children Funding source- Donald Krogstad Award for Early-Career Malian Scientists, Tulane University, and the Institute for Global Innovation, University of Birmingham, Prof. Krause’s; Dr. Sidibe, Dr. Asamane, Mr. Diarra, Prof Koita and Dr Manaseki-Holland/MaaCiwara research group

Research questions: What are the overall MnPs particle concentrations, total mass burden, and polymer types in drinking water and stool of children aged 6-36 months across aforementioned cohort of infants in Mali? Do initial findings indicate the existence of any type of geographical gradient (regional, urban vs rural) or other participant characteristics for this exposure?

Methods: Cross-sectional random samples from children drinking water and stools (plus their background characteristics survey) chosen from the 20 children (6-36month) who were 

sampled in 60 urban and 60 rural communities during the baseline data collection of MaaCiwara study (a nested study within the MaaCiwara 120 cluster RCT).

For this pilot study novel methods for extraction of MnPs was developed by UOB and staff from Mali trained for this and to conduct detection of MnPs using two methods at UOB laboratories. Florescent microscopy was conducted for 127 stool samples and 72 water samples to identify and quantify MnPs, including characterisation of their particle properties (size, form and shape). In addition, Raman spectroscopy was conducted on 116 stool and 19 water samples to identify the types of MnP polymers (e.g. Polyethylene (PE) or polyvinyl chloride (PVC) or Polypropylene (PP), etc). Characterisation of MnP additives through Pyrolisis GC-MS is currently set-up and will be conducted April-June.

Preliminary results:

• MnP were detected in over 90% of the stool samples and most of them were classified as ‘fibres’ and some were ‘fragments.

• Approximately 80% of the water samples were positive for MnP; both fibres and fragments were found (as shown in the figure below).

• Several types of polymers were identified, the most abundant being Polyvinyl Chloride (PVC), Polyethylene (PE) respectively.

Figure1: Shapes of the fragments and fibres found in the water and stool sample

Four stool samples showing fragments and fibres, three of the samples are illuminated green

 3.  Development of a unique stool sample bank for future MnP extraction

Further to the baseline data collection through MaaCiwara, stool samples are being collected through short-term and long-term follow-up data collection RCT rounds in 60 urban and 60 rural communities in Mali. The RCT is also collecting a wealth of information about the households, ranging from background characteristics to observation of plastic waste in their compounds and to child health outcomes. The nearly 9000 stools samples thus banked will enable future exploration of the possible relationship between MnP exposure and diarrhoea, respiratory symptoms, growth and development child health outcomes. The USTTB Mali team also have characterised the 17 common microbiomes in Mali infants, the role of which could be examined in exposure to MnPs.

Future plans for 2023-2030 and the need for funding:

• Finalise pilot analysis and establish what’s the range in MnP burden – does it vary - identify if any geographical gradient

We wish to assess family or child characteristics against exposure, and plot a map of geographical level findings. However, the numbers are not large enough in the pilot to enable adequate assessment against health outcomes which is also available.

• Extend stool/MnP sample bank for analysis beyond MaaCiwara project

• Build a MnP analysis team and Unit in Mali in order to analyse large numbers of stools being stored/frozen for future analysis. We plan this through:

-   Developing the fluorescent microscopy platform in Mali (microscope already available; needs to get the additional accessories),

-  Developing a Raman spectroscopy platform in Mali,

-  Training more young scientists on MnP sample collection, digestion, extraction, and analysis in Mali.

• Analyse larger stool sample sizes with increased health outcomes in order to assess any relationship between MnP exposure and diarrhoea, growth, development scores and respiratory symptoms.

• Conducting a study on the effect of microplastics on gut microbiome in children, starting with laboratory in vitro investigations, and apply this learning to the large number of MaaCiwara samples in urban and rural Mali, to enable a possible examination of the relationship of microbiomes, MnPs and child outcome.

Updated 28/02/2023


Donald Krogstad Award for Early-Career Malian Scientists and MRC UKRI