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A Farm to Fork Risk Assessment for the Use of Wastewater in Agriculture in Accra, Ghana.

Antwi-Agyei P, Cairncross S, Peasey A, Price V, Bruce J, Baker K, Moe C, Ampofo J, Armah G, Ensink J - PLoS ONE (2015)

Bottom Line: Prepared salad from street food vendors was found to be the most contaminated (4.23 Log E. coli/g), and that consumption of salad exceeded acceptable health limits.The source of produce and operating with a hygiene permit were found to influence salad microbial quality at kitchens.This study argues for a need to manage produce risk factors at all domains along the food chain, though it would be more effective to prioritise at markets and kitchens due to cost, ease of implementation and public health significance.

View Article: PubMed Central - PubMed

Affiliation: Environmental Health Group, Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel street, WC1E 7HT, London, United Kingdom.

ABSTRACT
The need to minimise consumer risk, especially for food that can be consumed uncooked, is a continuing public health concern, particularly in places where safe sanitation and hygienic practices are absent. The use of wastewater in agriculture has been associated with disease risks, though its relative significance in disease transmission remains unclear. This study aimed at identifying key risk factors for produce contamination at different entry points of the food chain. Over 500 produce and ready-to-eat salad samples were collected from fields, markets, and kitchens during the dry and wet seasons in Accra, Ghana, and over 300 soil and irrigation water samples were collected. All samples were analysed for E. coli, human adenovirus and norovirus using standard microbiological procedures, and real time RT-PCR. Finally, critical exposures associated with microbial quality of produce were assessed through observations and interviews. The study found that over 80% of produce samples were contaminated with E. coli, with median concentrations ranging from 0.64 to 3.84 Log E. coli/g produce. Prepared salad from street food vendors was found to be the most contaminated (4.23 Log E. coli/g), and that consumption of salad exceeded acceptable health limits. Key risk factors identified for produce contamination were irrigation water and soil at the farm level. Storage duration and temperature of produce had a significant influence on the quality of produce sold at markets, while observations revealed that the washed water used to rinse produce before sale was dirty. The source of produce and operating with a hygiene permit were found to influence salad microbial quality at kitchens. This study argues for a need to manage produce risk factors at all domains along the food chain, though it would be more effective to prioritise at markets and kitchens due to cost, ease of implementation and public health significance.

No MeSH data available.


Related in: MedlinePlus

Effect of soil (A) and irrigation water (B) on farm produce quality after adjusting for seasonality.Seasonality and soil interaction p = 0.004, 95% CI = -0.85, -0.17. Soil effect on produce contamination (point estimate for unit increase = 0.60 Log E. coli/g produce, 95% CI = 0.32, 0.87, p < 0.001). Effect of irrigation water on produce contamination (point estimate for unit increase = 0.14 Log E. coli/g produce, 95% CI = 0.02, 0.27, p = 0.027). Error bars = 95% confidence intervals (CI).
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pone.0142346.g002: Effect of soil (A) and irrigation water (B) on farm produce quality after adjusting for seasonality.Seasonality and soil interaction p = 0.004, 95% CI = -0.85, -0.17. Soil effect on produce contamination (point estimate for unit increase = 0.60 Log E. coli/g produce, 95% CI = 0.32, 0.87, p < 0.001). Effect of irrigation water on produce contamination (point estimate for unit increase = 0.14 Log E. coli/g produce, 95% CI = 0.02, 0.27, p = 0.027). Error bars = 95% confidence intervals (CI).

Mentions: The concentrations of E. coli found on farm produce increased with increased levels of E. coli found in soil or irrigation water (Fig 2). Seasonality modified the association between farm soil and farm produce quality with lower concentrations of E. coli found in the dry season as compared to the rainy season, with a 0.05 Log E. coli/g and 0.70 Log E. coli/g increase in produce contamination found per unit (Log E. coli/g) increase in soil contamination for the dry and rainy season respectively. In contrast, the effect of irrigation water quality on produce quality was found to be higher in the dry season as compared to the rainy season with a 0.20 Log E. coli/g and 0.06 Log E. coli/g increase in produce contamination per unit (Log E. coli/100 ml) increase of E. coli in irrigation water. However, the association between irrigation water and farm produce quality and the modification by seasonality was found to be non-significant (p = 0.19). The time of application of irrigation water, or poultry manure before sampling was found not to play any significant role on the concentration of E. coli found on farm produce (Table 1).


A Farm to Fork Risk Assessment for the Use of Wastewater in Agriculture in Accra, Ghana.

Antwi-Agyei P, Cairncross S, Peasey A, Price V, Bruce J, Baker K, Moe C, Ampofo J, Armah G, Ensink J - PLoS ONE (2015)

Effect of soil (A) and irrigation water (B) on farm produce quality after adjusting for seasonality.Seasonality and soil interaction p = 0.004, 95% CI = -0.85, -0.17. Soil effect on produce contamination (point estimate for unit increase = 0.60 Log E. coli/g produce, 95% CI = 0.32, 0.87, p < 0.001). Effect of irrigation water on produce contamination (point estimate for unit increase = 0.14 Log E. coli/g produce, 95% CI = 0.02, 0.27, p = 0.027). Error bars = 95% confidence intervals (CI).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4640866&req=5

pone.0142346.g002: Effect of soil (A) and irrigation water (B) on farm produce quality after adjusting for seasonality.Seasonality and soil interaction p = 0.004, 95% CI = -0.85, -0.17. Soil effect on produce contamination (point estimate for unit increase = 0.60 Log E. coli/g produce, 95% CI = 0.32, 0.87, p < 0.001). Effect of irrigation water on produce contamination (point estimate for unit increase = 0.14 Log E. coli/g produce, 95% CI = 0.02, 0.27, p = 0.027). Error bars = 95% confidence intervals (CI).
Mentions: The concentrations of E. coli found on farm produce increased with increased levels of E. coli found in soil or irrigation water (Fig 2). Seasonality modified the association between farm soil and farm produce quality with lower concentrations of E. coli found in the dry season as compared to the rainy season, with a 0.05 Log E. coli/g and 0.70 Log E. coli/g increase in produce contamination found per unit (Log E. coli/g) increase in soil contamination for the dry and rainy season respectively. In contrast, the effect of irrigation water quality on produce quality was found to be higher in the dry season as compared to the rainy season with a 0.20 Log E. coli/g and 0.06 Log E. coli/g increase in produce contamination per unit (Log E. coli/100 ml) increase of E. coli in irrigation water. However, the association between irrigation water and farm produce quality and the modification by seasonality was found to be non-significant (p = 0.19). The time of application of irrigation water, or poultry manure before sampling was found not to play any significant role on the concentration of E. coli found on farm produce (Table 1).

Bottom Line: Prepared salad from street food vendors was found to be the most contaminated (4.23 Log E. coli/g), and that consumption of salad exceeded acceptable health limits.The source of produce and operating with a hygiene permit were found to influence salad microbial quality at kitchens.This study argues for a need to manage produce risk factors at all domains along the food chain, though it would be more effective to prioritise at markets and kitchens due to cost, ease of implementation and public health significance.

View Article: PubMed Central - PubMed

Affiliation: Environmental Health Group, Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel street, WC1E 7HT, London, United Kingdom.

ABSTRACT
The need to minimise consumer risk, especially for food that can be consumed uncooked, is a continuing public health concern, particularly in places where safe sanitation and hygienic practices are absent. The use of wastewater in agriculture has been associated with disease risks, though its relative significance in disease transmission remains unclear. This study aimed at identifying key risk factors for produce contamination at different entry points of the food chain. Over 500 produce and ready-to-eat salad samples were collected from fields, markets, and kitchens during the dry and wet seasons in Accra, Ghana, and over 300 soil and irrigation water samples were collected. All samples were analysed for E. coli, human adenovirus and norovirus using standard microbiological procedures, and real time RT-PCR. Finally, critical exposures associated with microbial quality of produce were assessed through observations and interviews. The study found that over 80% of produce samples were contaminated with E. coli, with median concentrations ranging from 0.64 to 3.84 Log E. coli/g produce. Prepared salad from street food vendors was found to be the most contaminated (4.23 Log E. coli/g), and that consumption of salad exceeded acceptable health limits. Key risk factors identified for produce contamination were irrigation water and soil at the farm level. Storage duration and temperature of produce had a significant influence on the quality of produce sold at markets, while observations revealed that the washed water used to rinse produce before sale was dirty. The source of produce and operating with a hygiene permit were found to influence salad microbial quality at kitchens. This study argues for a need to manage produce risk factors at all domains along the food chain, though it would be more effective to prioritise at markets and kitchens due to cost, ease of implementation and public health significance.

No MeSH data available.


Related in: MedlinePlus