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

  • Geophagy among East African Chimpanzees: consumed soils provide protection from plant secondary compounds and bioavailable iron 2019-12-01


    Geophagy, the intentional consumption of earth materials, has been recorded in humans and other animals. It has been hypothesized that geophagy is an adaptive behavior, and that clay minerals commonly found in eaten soil can provide protection from toxins and/or supplement micronutrients. To test these hypotheses, we monitored chimpanzee geophagy using camera traps in four permanent sites at the Budongo Forest Reserve, Uganda, from October 2015–October 2016. We also collected plants, and soil chimpanzees were observed eating. We analyzed 10 plant and 45 soil samples to characterize geophagic behavior and geophagic soil and determine (1) whether micronutrients are available from the soil under physiological conditions and if iron is bioavailable, (2) the concentration of phenolic compounds in plants, and (3) if consumed soils are able to adsorb these phenolics. Chimpanzees ate soil and drank clay-infused water containing 1:1 and 2:1 clay minerals and > 30% sand. Under physiological conditions, the soils released calcium, iron, and magnesium. In vitro Caco-2 experiments found that five times more iron was bioavailable from three of four soil samples found at the base of trees. Plant samples contained approximately 60 μg/mg gallic acid equivalent. Soil from one site contained 10 times more 2:1 clay minerals, which were better at removing phenolics present in their diet. We suggest that geophagy may provide bioavailable iron and protection from phenolics, which have increased in plants over the last 20 years. In summary, geophagy within the Sonso community is multifunctional and may be an important self-medicative behavior.

  • Accumulation of uranium and heavy metals in the soil–plant system in Xiazhuang uranium ore field, Guangdong Province, China 2019-12-01


    Plants that have grown for many years in the special environmental conditions prevailing in mining areas are naturally screened and show strong capacity to adapt to their environment. The present study investigated the enrichment characteristics of U and other heavy metals (As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni) in the soil–plant system in Xiazhuang uranium mine. Four dominant plants (Castanopsis carlesii, Rhus chinensis, Liriodendron chinense, and Sapium discolor) and soil samples were collected from the mined areas, unmined areas, and background areas away from the ore field. U, As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni concentrations were analyzed by ICP-MS. The results demonstrate that (1) The highest concentrations of U (4.1–206.9 mg/kg) and Pb (43.3–126.0 mg/kg) with the geoaccumulation index (Igeo) greater than 1 show that they are the main soil pollutants in the research area. (2) The biological accumulation coefficient (LBAC) values for Cd, Mn, and Cu are greater than zero in S. discolor, L. chinense, and C. carlesii and these three plants indicate that they can be used for remediation of the soil in the ore field. (3) R. chinensis inhibits the accumulation of heavy metals and shows sensitive pigment responses to the accumulation of U in the leaves. L. chinense has the strongest enrichment effect on heavy metals but exhibits weak biochemical responses under U stress. C. carlesii demonstrates strong adaptation to U and can maintain healthy pigment characteristics in case of high U enrichment. (4) S. discolor, L. chinense, C. carlesii and R. chinensis have strong tolerance to U toxicity and different biochemical responses.

  • Distribution, sources and health risk assessment of contaminations in water of urban park: A case study in Northeast China 2019-12-01


    This case study was performed to determine whether the pollutants in water of urban park could bring health risk to human engaging in water-related activities such as swimming and provide evidence demonstrating the critical need for strengthened recreational water resources management of urban park. TN, NH4+-N, TP, Cu, Mn, Zn, Se, Pb, As, Cd and Cr(VI) contents were determined to describe the spatial distribution of contaminations; sources apportionment with the method of correlation analysis, factor analysis and cluster analysis were followed by health risk assessment for swimmers of different age groups. The results reveal that element contents in all sites do not exceed Chinese standard for swimming area and European Commission standard for surface water; all detected elements except Cr(VI) have a tendency to accumulate in the location of lake crossing bridge; Mn and Zn are considered to have the same pollution source including geogenic and anthropogenic sources by multivariable analysis. Carcinogenic risks of different age groups descend in the same order with non-carcinogenic risks. Among all elements, Zn and Mn contribute the lowest non-carcinogenic risk (5.1940E-06) and the highest non-carcinogenic risk (7.9921E-04) through skin contact pathway, respectively. The total average personal risk for swimmers in swimming area is 1.9693E-03, and this site is not suitable for swimming. Overall, it is possible that swimmers are exposed to risk via the dermal route when carrying out water-related activities, it is recommended that necessary precautions and management should be taken in other similar locations around the world.