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

  • Health risks and source identification of dietary exposure to indicator polychlorinated biphenyls (PCBs) in Lanzhou, China 2019-09-19


    Polychlorinated biphenyls (PCBs) are widely present in multiple environmental media even long after the phaseout, posing a health risk to the general population. Dietary intake is the major exposure route of PCBs; however, information is limited regarding PCBs in food that people directly consume. This study aims to measure personal exposure to indicator PCBs, evaluate the health risks, and identify their sources in a typical metropolitan city in China. Multi-day food samples were collected from 21 subjects in Lanzhou, Gansu Province, in two seasons using the duplicate plate method. Samples were extracted and analyzed for seven indicator PCBs using gas chromatography/mass spectrometry. Average daily doses (ADDs) of ∑7PCBs were estimated using Monte Carlo analysis with food intake information. Results show that PCB-118 and PCB-180 were the major congeners in food samples with average concentrations of 1.42 and 1.11 ng/g, respectively. The average (± SD) ADD of ∑7PCBs was 26.47 ± 22.10 ng/kg day among adults aged 18–69 years and displayed small variation across age groups. Comparing with the chronic RfD of 7 ng/kg day, 67% of people had their ADDs exceeding this threshold. The median cancer risk was 5.52 × 10−5, and 51% of residents had risks exceeding the action level of 10−4. The principal component analysis identified waste incineration, gasoline engine production, and leakage of #1 PCBs as the major PCBs sources. In conclusion, a large portion of Lanzhou residents has high non-cancer and cancer risks from dietary exposure to PCBs, which warrants control actions targeting these major sources.

  • Comprehensive assessment of heavy metals pollution of farmland soil and crops in Jilin Province 2019-09-18


    As a major agricultural province in China, it is necessary to study the content of heavy metals in farmland soil and crop in Jilin Province and to evaluate the risks to ecology and human health. This study presented the work completed on 79 soil samples, 10 rice samples, 66 maize samples and 15 soybean samples collected from Jilin Province farmland and evaluated six heavy metals (Zn, Cu, Pb, Cd, Hg and As) concentrations. The results showed that the concentrations of the six heavy metals in farmland soil and crop samples from Jilin Province basically met the soil standards and food health standards of China. The agricultural soil pollution spatial distribution was the most serious in the south of Jilin Province and the lightest in the west. The non-carcinogenic risks faced by children eating crops were higher than those of adults, but the carcinogenic risks were lower than those of adults. Both of the two health risks to adults and children from eating crops were very limited. The results would help determine the heavy metals pollution in farmland soil in Jilin Province efficiently and accurately and helped decision makers to achieve a balance between production and environmental regulation.

  • Sustainability of agricultural and wild cereals to aerotechnogenic exposure 2019-09-14


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