Know thy water: If it’s dry, I’m gonna water rather than lose a crop

Foodborne disease outbreaks associated with fresh produce irrigated with contaminated water are a constant threat to consumer health. In this study, the impact of irrigation water on product safety from different food production systems (commercial to small-scale faming and homestead gardens) was assessed.

drip-irrigation-carrots-jun-16Hygiene indicators (total coliforms, Escherichia coli), and selected foodborne pathogens (Salmonella spp., Listeria monocytogenes, and Escherichia coli O157:H7) of water and leafy green vegetables were analyzed. Microbiological parameters of all irrigation water (except borehole) exceeded maximum limits set by the Department of Water Affairs for safe irrigation water. Microbial parameters for leafy greens ranged from 2.94 to 4.31 log CFU/g (aerobic plate counts) and 1 to 5.27 log MPN/100g (total coliforms and E. coli). Salmonella and E. coli O157:H7 were not detected in all samples tested but L. monocytogenes was present in irrigation water (commercial and small-scale farm, and homestead gardens).

This study highlights the potential riskiness of using polluted water for crop production in different agricultural settings.

Assessment of irrigation water quality and microbiological safety of leafy greens in different production systems

Journal of Food Safety, 2 November 2016, DOI: 10.1111/jfs.12324

http://onlinelibrary.wiley.com/doi/10.1111/jfs.12324/abstract;jsessionid=883317B2001984CC39815B1792B68759.f04t01

Irrigation water safety in Penn.

Recent produce-associated foodborne illness outbreaks have been attributed to contaminated irrigation water. This study examined microbial levels in Pennsylvania surface waters used for irrigation, relationships between microbial indicator organisms and water physicochemical characteristics, and the potential use of indicators for predicting the presence of human pathogens.

A total of 153 samples taken from surface water sources used for irrigation in southeastern Pennsylvania were collected from 39 farms over a 2-year period. Samples were analyzed for six microbial indicator organisms (aerobic plate count, Enterobacteriaceae, coliform, fecal coliforms, Escherichia coli, and enterococci), two human pathogens (Salmonella and E. coli O157), and seven physical and environmental characteristics (pH, conductivity, turbidity, air and water temperature, and sampling day and 3-day-accumulated precipitation levels).

Indicator populations were highly variable and not predicted by water and environmental characteristics. Only five samples were confirmed positive for Salmonella, and no E. coli O157 was detected in any samples. Predictive relationships between microbial indicators and the occurrence of pathogens could therefore not be determined.

Microbial survey of Pennsylvania surface water used for irrigating produce crops

Journal of Food Protection®, Number 6, June 2016, pp. 896-1055, pp. 902-912(11)

Draper, Audrey D.; Doores, Stephanie; Gourama, Hassan; LaBorde, Luke F.

http://www.ingentaconnect.com/contentone/iafp/jfp/2016/00000079/00000006/art00002

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Irrigation water, produce and pathogens

The microbiological sanitary quality and safety of leafy greens and strawberries were assessed in the primary production in Belgium, Brazil, Egypt, Norway and Spain by enumeration of Escherichia coli and detection of Salmonella, Shiga toxin-producing E. coli (STEC) and Campylobacter.

strawberryWater samples were more prone to containing pathogens (54 positives out of 950 analyses) than soil (16/1186) and produce on the field (18/977 for leafy greens and 5/402 for strawberries). The prevalence of pathogens also varied markedly according to the sampling region. Flooding of fields increased the risk considerably, with odds ratio (OR) 10.9 for Salmonella and 7.0 for STEC.

A significant association between elevated numbers of generic E. coli and detection of pathogens (OR of 2.3 for STEC and 2.7 for Salmonella) was established. Generic E. coli was found to be a suitable index organism for Salmonella and STEC, but to a lesser extent for Campylobacter. Guidelines on frequency of sampling and threshold values for E. coli in irrigation water may differ from region to region. 

Risk Factors for Salmonella, shiga toxin-producing Escherichia coli and Campylobacter occurrence in primary production of leafy greens and strawberries

International Journal of Environmental Research and Public Health

Siele Ceuppens, Gro S. Johannessen, Ana Allende, Eduardo César Tondo,  Fouad El-Tahan, Imca Sampers, Liesbeth Jacxsens, and  Mieke Uyttendaele

http://www.mdpi.com/1660-4601/12/8/9809

Irrigation water and produce safety

Back before there was youtube, we started videoing my friend, Jeff Wilson, about farming stuff.

boog.powell.mesquite.cookingWe knew irrigation water was an issue, but it was one most didn’t want to talk about.

Researchers at Cornell have reported that environmental (i.e., meteorological and landscape) factors and management practices can affect the prevalence of foodborne pathogens in produce production environments.

This study was conducted to determine the prevalence of Listeria monocytogenes, Listeria species (including L. monocytogenes), Salmonella, and Shiga toxin–producing Escherichia coli (STEC) in produce production environments and to identify environmental factors and management practices associated with their isolation.

Ten produce farms in New York State were sampled during a 6-week period in 2010, and 124 georeferenced samples (80 terrestrial, 33 water, and 11 fecal) were collected. L. monocytogenes, Listeria spp., Salmonella, and STEC were detected in 16, 44, 4, and 5% of terrestrial samples, 30, 58, 12, and 3% of water samples, and 45, 45, 27, and 9% of fecal samples, respectively. Environmental factors and management practices were evaluated for their association with terrestrial samples positive for L. monocytogenes or other Listeria species by univariate logistic regression; analysis was not conducted for Salmonella or STEC because the number of samples positive for these pathogens was low. Although univariate analysis identified associations between isolation of L. monocytogenes or Listeria spp. from terrestrial samples and various water-related factors (e.g., proximity to wetlands and precipitation), multivariate analysis revealed that only irrigation within 3 days of sample collection was significantly associated with isolation of L. monocytogenes (odds ratio = 39) and Listeria spp. (odds ratio = 5) from terrestrial samples.

These findings suggest that intervention at the irrigation level may reduce the risk of produce contamination.

Irrigation is significantly associated with an increased prevalence of Listeria monocytogenes in produce production environments in New York State

Journal of Food Protection®, Number 6, June 2015, pp. 1064-1243, pp. 1132-1141(10), DOI: http://dx.doi.org/10.4315/0362-028X.JFP-14-584

Weller, Daniel; Wiedmann, Martin; Strawn, Laura K.

http://www.ingentaconnect.com/content/iafp/jfp/2015/00000078/00000006/art00010

As always, more research required: Study analyzes tomato production practices

Doug Ohlemeier of The Packer writes that tomato production practices don’t significantly affect bacteria levels and the study’s results point to the need for additional research, according to University of Maryland and Rutgers University researchers.

tomato.traceabilityThat’s the conclusion of a study scheduled to be published in the March issue of the International Journal of Food Microbiology.

From July to September 2012, researchers from the College Park-based University of Maryland’s College of Agriculture and Natural Resources’ Center for Food Safety and Security Systems and New Brunswick, N.J.-based Rutgers’ Cooperative Extension collected and tested 422 samples from 24 conventional and organic tomato farms from four growing regions in Maryland, Delaware and New Jersey.

The researchers analyzed 259 tomato fruit samples and also examined irrigation water, compost, field soil and pond sediment for Salmonella enterica, shiga toxin and bacterial indicators in pre-harvest tomatoes.

They didn’t detect any salmonella on the farms and the prevalence of shiga toxin, a byproduct of E. coli, was very low, said Shirley Micallef, an assistant professor who heads the Maryland university’s food safety center and Plant Science and Landscape Architecture department.

One curious finding was an apparent difference in bacteria present on tomatoes that touch the ground vs. tomatoes higher in a vine canopy that don’t contact the plastic or straw mulch.

Researchers found indicator bacteria on the ones that connected with the ground but no pathogens, Micallef said.

That discovery doesn’t mean tomatoes that touch the ground shouldn’t be harvested but only points to the need for additional investigation, she said.

Another finding was groundwater from the end of drip lines possessed higher indicator bacteria counts than the source water, Micallef said.

tomato.dump.tankThe difference in microbiological quality of water signals potential risk and points to the need for growers to conduct more frequent drip line system maintenance by testing water at the end of the line, she said.

The research also found no difference in contamination risk between conventional and organic tomatoes and study was also different because it focused on small and medium-sized growers, Micallef said.

“It was encouraging we didn’t find a huge problem because here in the Mid-Atlantic, we have had outbreaks associated with tomatoes,” she said. “It’s good to see growers really paying attention to GAPs (good agricultural practices) and trying to implement food safety practices as best they can in the fields. They probably do help to reduce the risk.”

Do you know what’s in your water? Proposed regs put responsibility on growers

Federal regulators have softened some proposed restrictions to farming practices in the name of food safety, but the Yakima Valley’s tree fruit industry officials say the proposal is still too much.

two fistin wilsonFruit trade officials plan to submit comments to the U.S. Food and Drug Administration asking for additional allowances on proposed irrigation water quality standards called for by the Food Safety Modernization Act.

“It’s still complicated and still going to be costly for your grower,” said Chris Schlect, president of the Northwest Horticultural Council, a trade group that represents the fruit industry in federal affairs and international trade.

The Food Safety Modernization Act, or FSMA, is a 2011 federal law that mandated sweeping changes to the entire food production system to prevent the spread of food-borne illnesses, which kill 3,000 people a year nationwide and hospitalize 128,000, according to estimates from the Centers for Disease Control and Prevention.

It includes everything from hand washing to preventing acts of terrorism.

The FDA is charged with implementing the law and is taking public comments on its second attempt to impose the nuts and bolts of the regulation, spelled out in mind-numbing, scientific detail over several subsections that together would take up thousands upon thousands of pages.

“I don’t think any normal person can understand it,” Schlect said. “George Orwell would roll over in his grave.”

Growers objected most to a suggested stipulation that would prohibit any fruit from contact with water that does not meet the swimming quality standards set by the Environmental Protection Agency and would also require farmers to periodically test their water. If the test came back negative, the growers would have to shut off irrigation.

Most of the Yakima Valley farms rely on open canals and though many orchards use low sprinklers that water under the tree canopy, they also employ overhead sprinklers to cool fruit during the scorching peak of summer.

In the first round of public comments last year, Schlect and other grower groups argued the proposed rules would hold orchardists responsible for contamination upstream, and treat fruit that hangs on the trees the same as produce grown in the dirt.

While FDA officials didn’t soften the water quality standards in their revised proposal, they have suggested granting allowances for the time between the last round of irrigation and harvest. They also might allow growers to test water collectively, maybe at certain points in the canal.

Meanwhile, The Produce News reports that different standards for packinghouses under the Food Safety Modernization Act based on their location will cause confusion within the industry and are not science-based, produce industry groups told officials at the Food & Drug Administration during a Thursday public meeting on FSMA changes.

Under the FDA’s current interpretation of FSMA, on-farm packinghouses would need to meet produce safety standards, but off-farm operations, which must register with the FDA, would have to meet more extensive and costly preventive control requirements.

Registered facilities that only handle raw agriculture commodities and don’t conduct further processing should be covered under the produce safety rule, Reggie Brown, executive vice president of the Florida Tomato Exchange, argued during the meeting held in College Park, MD. Food safety and public heath benefits are likely to be best served by a single rule, he said.

My friend and collaborator, farmer Jeff Wilson addressed this issue over 10 years ago, long before youtube existed. We found the video.

 

 

Does E. coli persist in strawberry fields (not forever)

Irrigation water quality is one of those nagging issues for on-farm food safety and fresh produce: it’s difficult to model how persistent E. coli is and just how much of a threat is present. Or as my farmer friends say, if I’m going to lose the crop, I’m going to irrigate.

beatles-strawberry-fields-foreverA two-year field experiment was conducted in order to evaluate the persistence of generic Escherichia coli in strawberry after irrigation with naturally E. coli-contaminated surface water. Sixteen experimental plots representing actual field conditions were set, including two methods of irrigation (overhead and subsurface drip) and two mulch types (straw and plastic). Two irrigations were performed each year with water having an E. coli content varying between 460 and 2242 CFU per 100 ml. Strawberries were harvested before irrigation and 1, 4 and 24 h following irrigation. E. coli counts could not be determined in any of the 256 strawberry samples. Enrichment procedure revealed more positive samples under straw mulch (6.4%) compared to plastic mulch (4.3%), but this difference was not statistically significant (P = 0.3991). Higher strawberry contamination was also observed in overhead irrigation treatments (8.6%) compared to drip irrigation (2.1%) (P = 0.0674). The risk to detect E. coli in overhead-irrigated strawberries was 4.5-fold higher than in strawberries under drip irrigation. Four hours following irrigation, the risk to detect E. coli in fruits was 4.0-fold lower than the risk observed 1 h after irrigation. Increasing the delay to 24 h led to a 7.4-fold lower risk. In actual conditions that may be encountered in strawberry productions, this study showed a limited persistence of E. coli in strawberries following irrigation.

Persistence of Escherichia coli following irrigation of strawberry grown under four production systems: Field experiment

ScienceDirect

Mylene Genereux, Michele Grenier, Caroline Cote

Food Control, Volume 47, January 2015, Pages 103–107, DOI: 10.1016/j.foodcont.2014.06.037

http://www.sciencedirect.com/science/article/pii/S0956713514003661

Utah: Campylobacter outbreak in Saratoga Springs probably caused by cross-connecting water lines

I’m not familiar with the practice, but apparently when crews shut off the city’s irrigation lines in the fall in Saratoga Springs, Utah, some residents tap into culinary pipes, getting water for outdoor use.

Deseret News reports that the city imposed the fine for cross-connecting culinary and irrigation lines after a Campylobacter outbreak sickened dozens of residents earlier this summer. Cross-connecting can contaminate culinary water and may have caused the outbreak.

Mayor Mia Love said anyone caught cross-connecting with a previous warning will be fined $10,000, adding, "It certainly sends a message saying we’re very serious about keeping the water clean. We’re not taking it lightly."