FOOD CONTAMINATION LINKED TO WATER QUALITY
According to an article on the Impact of Water Quality to the Food Industry in South Africa by Paul J Oberholster and Anna maria Botha,” the food-processing industry involves the total environment from farm to customer, presenting numerous pathways for the potential contamination of food. Irrigation water has been found to be a major source of faecal contamination with many outbreaks of related diseases linked to contaminated irrigation water. In South Africa the annual water usage for irrigation purposes is 59% of the total water requirement with river and dam water as the main irrigation source. Certain rivers in South Africa, however, have been reported to contain high levels of microbial pollutants (especially E. coli) which can act as a vehicle for food contamination. In this chain, the main pre-harvest sources of contamination include: (a) irrigation water, (b) manure, (c) soil and (d) inadequate sanitation, while post-harvesting pathways of contamination are from food handling. The following contamination routes of food are particularly relevant to consumers: (a) while it is in its raw or unprocessed state, (b) during processing, (c) during packaging, (d) during transportation and (e) during delivery and display. Although most of these can be managed with relative ease, exposure pathways of crops to toxic metals through contaminated soil and water are more difficult to manage. In a recent study, accumulation of toxic metals in fresh produce and grain crops was reported.
Food and water can serve as vehicles that transmit microbial contamination. Microbial pollutants of water resources pose a serious health risk to humans and animals; these include Escherichia coli, Shigella spp., Salmonella spp. and protozoan parasites such as Cryptosporidium hominis and Giardia lamblia species. The latter are regarded as important pathogens since they can cause diarrhoea in humans and animals, which may result in the death of immunocompromised individuals, children with malnutrition, transplant recipients, patients receiving chemotherapy for cancer and patients with immunosuppressive infectious diseases. South Africa regularly experiences outbreaks of diarrhoea, which may be associated with the use of contaminated water. In 2005, for example, in the town of Delmas situated in the upper Olifants River catchment, an outbreak resulted in 528 reported cases with four deaths and 69 people hospitalised. The outbreak is thought to have been attributed to microbial contamination of water resource, although subsequent studies in this area could not identify the causative agent. Waterborne diarrhoeal outbreaks where no aetiological agent is detected may be attributed to Cryptosporidium spp. and Giardia spp.”
The impact of poor water quality is greater than just on a medical scale but has a severe impact on food exporting. Water is a limited and scarce resource particularly in South Africa, we therefore need to look after it and manage it more effectively. The lack of good quality water can also be seen as a possible ‘barrier-to-trade’. This is because fruit exported from developing countries like South Africa are often incorrectly perceived to be produced under unhygienic conditions or are considered of poor quality and safety.” Public health threats are further increased due to an increase in immuno-compromised individuals, global procurement and movement of fresh produce. There has also been an increase of fresh produce consumption over the past twenty years, resulting in more cases of foodborne associated disease outbreaks. Given that the world has become an interconnected “global village” as well as the importance of our Fruit safety and local water quality, ensuring the safety of produce from farm to market has never been so critical. Supermarkets are therefore very sensitive to any possible risks that might arise due to food safety factors, so it is paramount for local producers that public perception about the safety of our food supplies is not compromised.
What can farmers do about this? I found some great advice in the latest issue of SA Fruit Journal: “Firstly, ensure more effective implementation of international food safety standards and requirements, such as water quality management and effective hygiene and sanitation systems,” says Korsten. “Secondly, invest in human capital and contribute towards the training of a new cadre of young scientists in horticultural food safety. Go into partnership with research institutes doing cutting edge research and provide financial support to these institutions of excellence. Establish an enabling platform to take the novel technology and new knowledge to the farm to ensure effective up take and provision of real-time solutions. “Furthermore, encourage government to do the same and put pressure on local municipalities to ‘clean-up-their-act’ when it comes to wastewater management. Collective action between research institutions, farmers and the government therefore remains critical to protect local producers and consumers.” Appropriate water testing to ensure water is free of waterborne pathogens is also important, she says. “However, keep in mind that recent developments in water research technology and diagnostic test methods have been changing so rapidly that most of the traditional methods used in water and food laboratories are now outdated and obsolete, often providing inaccurate or meaningless results.” “In my opinion, a lot of farmers are currently wasting their money with unnecessary testing of water and fruit samples if laboratories are using old technologies,” says Korsten. Water used in packhouses’ wash stations and in bathrooms on farms should also be managed effectively to ensure it is potable. “The effective washing of fruit (with the correct disinfectants) probably offers one of the best opportunities to get rid of newly introduced pathogens. This approach, if implemented rigorously, can provide a real-time solution similar to the concept of ‘hurdletechnology’ used in the food industry.” This does come ‘at a cost’ to producers (in terms of increased water replenishment rates and purification costs) and can negatively affect the water footprint of their produce. Korsten says, “Contaminated water could still pose a food risk for waterborne pathogens. This is something that responsible producers should take very seriously, especially given emerging research on antimicrobial resistance.” And since some of the foodborne pathogens can attach and survive on certain fruit surfaces, it is important to consider certain interventions by focusing on applying crop protectants that are known to also inhibit the growth of some waterborne pathogens (such as Dithane, Copper hydroxide, Captan Flo and Prosper 500 EC).” Although agricultural chemicals can be used to reduce the risk of pathogens on fruit, it is important to be aware that some of the chemicals can even support pathogen growth. “This should be taken into consideration in a risk assessment approach for each cultivar and spray program used on farms. Irrigate and use pesticides at the correct dosage, follow the described withholding periods and use the pesticide strategically to minimise waterborne pathogen growth.”