SEGH Articles

SEGH2019 Prize Winners Series: Amy Sansby

05 August 2019
Amy Sansby, a veterinary student at the University of Nottingham, won the best overall ECR poster prize and shares a more detailed account of her study with us!

Aquaculture is the fastest-growing livestock sector globally. Between 1961 and 2016 the average increase in global fish consumption was 3.2%, which exceeded the consumption of meat from all terrestrial animals combined (2.8%).  Aquaculture samples can be used to provide a relatively cheap protein source in many countries and is especially important in developing countries where other protein sources may not be available or affordable. Aquaculture also provides income to developing countries, such as Kenya, where 2,500,000 people are employed both directly and indirectly. It can also provide an income too low skilled members of the community who may otherwise not have an income. Therefore, it is important that this sector grows in a safe and sustainable manner in order to ensure that the food is both safe and nutritionally beneficial to all consumers.

Whilst in many countries the use of antibiotics for growth promotion or metaphylaxis is banned, these practices are still occurring in aquaculture. This can lead to an increase in antimicrobial-resistant populations of bacteria, and additionally elevated levels of antimicrobial residues within the food. Other routes to antibiotic exposure include contamination of water with pharmaceutical products; wastewater runoff from humans; and bad agricultural practices.

This study was part of a larger collaborative effort aiming to assess how a range of pollutants, including antibiotics and heavy metals, affect aquaculture samples that are intended for human consumption. The aim was to evaluate the quality of aquaculture produce from Kenya (a growing country within the aquaculture sector) and Vietnam (a large exporter to several European countries, including the UK). Kenyan aquaculture samples were obtained directly from multiple sites around Lake Victoria, and Vietnamese aquaculture samples were purchased in the UK from major supermarkets. This allowed a comparison to be made between aquaculture samples from both countries.


Tilapia sampling in Kenya


To evaluate antibiotic residues within the fish, a Premi-test 25 kit was used. This test uses a thermophilic bacteria (Bacillus stearothermophilus) which is susceptible to the following antimicrobial compounds: β-lactams, Cephalosporins, Macrolides, Tetracyclines, Sulphonamides, Aminoglycosides, Quinolones, Amphenicoles and Polypeptides. A positive result indicates a residue level above the EU maximum residue level (MRL). Antibiotic resistance was evaluated using polymerase chain reactions (PCR) which amplifies specific genetic elements, if present. The resistance genes for Tetracycline and Ampicillin were examined in this study.

Extracting fish muscle juice for Premi-test 25 on the boat while sampling in Kenya


76% of Kenyan samples and 55% of Vietnamese samples tested positive for antibiotic residues. Genetic elements for Tetracycline resistance were present in fish samples from both counties, and all Kenyan fish tested positive for Ampicillin resistance. This highlights the need for further research to investigate the source of the residues and resistance elements, and also the importance of working with aquaculture farmers in order to reduce contamination of their products.

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Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Earthworms and vermicompost: an eco-friendly approach for repaying nature’s debt 2020-01-23


    The steady increase in the world’s population has intensified the need for crop productivity, but the majority of the agricultural practices are associated with adverse effects on the environment. Such undesired environmental outcomes may be mitigated by utilizing biological agents as part of farming practice. The present review article summarizes the analyses of the current status of global agriculture and soil scenarios; a description of the role of earthworms and their products as better biofertilizer; and suggestions for the rejuvenation of such technology despite significant lapses and gaps in research and extension programs. By maintaining a close collaboration with farmers, we have recognized a shift in their attitude and renewed optimism toward nature-based green technology. Based on these relations, it is inferred that the application of earthworm-mediated vermitechnology increases sustainable development by strengthening the underlying economic, social and ecological framework.

    Graphic abstract

  • Plasticizers and bisphenol A in Adyar and Cooum riverine sediments, India: occurrences, sources and risk assessment 2020-01-23


    Adyar and Cooum, the two rivers intersecting Chennai city, are exposed to serious pollution due to the release of large quantities of dumped waste, untreated wastewater and sewage. Sediments can act as repository for emerging organic contaminants. Hence, we have monitored the occurrence and risk associated with plasticizers [six phthalic acid esters (PAEs), bis(2-ethyl hexyl adipate) (DEHA)] and bisphenol A (BPA) in surface riverine sediments of Adyar and Cooum rivers from residential/commercial, industrial and electronic waste recycling sites. Σ7plasticizers (PAEs + DEHA) in the Adyar riverine sediment (ARS) and Cooum riverine sediment (CRS) varied between 51.82–1796 and 28.13–856 ng/g, respectively. More than three-fourth of Σ7plasticizers came from bis(2-ethylhexyl) phthalate (DEHP), in accordance with the high production and usage of this compound. BPA varied between 10.70–2026 and 7.58–1398 ng/g in ARS and CRS, respectively. Average concentrations of plasticizers and BPA were four times higher in electronic waste (e-waste) recycling sites when compared with industrial and residential/commercial sites. BPA and DEHP showed a strong and significant correlation (R2 = 0.7; p < 0.01) in the e-waste sites thereby indicating common source types. Sites present at close proximity to raw sewage pumping stations contributed to 70% of the total BPA observed in this study. For the derived pore water concentration of plasticizers and BPA, the ecotoxicological risk has been found to be higher in ARS over CRS. However, sediment concentrations in all the sites of ARS and CRS were much below the recommended serious risk concentration for human (SRChuman) and serious risk concentration for ecotoxicological (SRCeco).

  • Distribution of metal(loid)s in particle size fraction in urban soil and street dust: influence of population density 2020-01-18


    Assessment of street dust is an invaluable approach for monitoring atmospheric pollution. Little information is available on the size distribution of contaminants in street dusts and urban soils, and it is not known how the population density would influence them. This research was carried out to assess the size distribution of trace metal(loid)s in street dust and urban soil, and to understand how population density might influence the size-resolved concentration of metal(loid)s. Three urban areas with a high, medium and low population density and a natural area were selected and urban soil and street dust sampled. They were fractionated into 8 size fractions: 2000–850, 850–180, 180–106, 106–50, 50–20, 20–10, 10–2, and < 2 µm. The concentration of Pb, Zn, Cu, Cd, Cr, Ni, As, and Fe was determined, and enrichment factor and grain size fraction loadings were computed. The results indicated that the concentration of Pb, Zn, Cu, Cd, and Cr was highly size dependent, particularly for particles < 100 µm, especially for street dust. Low concentrations of Ni and As in street dust and urban soil were size and population density independent. Higher size dependency of the metals concentration and the higher degree of elemental enrichment in the street dust fractions than the urban soils indicate higher contribution of human-induced pollution to the dust. Findings also confirm the inevitability of size fractionation when soils or dusts are environmentally assessed, particularly in moderately to highly polluted areas. Otherwise, higher concentrations of certain pollutants in fine-sized particles might be overlooked leading to inappropriate decisions for environmental remediation.