Microbiological study of ready-to-eat salad vegetables from retail establishments uncovers a national outbreak of salmonellosis

The increasing availability of bagged prepared salad vegetables reflects consumer demand for fresh, healthy, convenient, and additive-free foods that are safe and nutritious. During May and June 2001 a study of retail bagged prepared ready-to-eat salad vegetables was undertaken to determine the microbiological quality of these vegetables. Examination of the salad vegetables revealed that the vast majority (3,826 of 3,852 samples; 99.3%) were of satisfactory or acceptable microbiological quality according to Public Health Laboratory Service microbiological guidelines, while 20 (0.5%) samples were of unsatisfactory microbiological quality. Unsatisfactory quality was due to Escherichia coli and Listeria spp. (not Listeria monocytogenes) levels in excess of 10(2) CFU/g. However, six (0.2%) samples were of unacceptable microbiological quality because of the presence of Salmonella (Salmonella Newport PT33 [one sample], Salmonella Umbilo [three samples], and Salmonella Durban [one sample]) or because of a L. monocytogenes level of 660 CFU/g, which indicates a health risk. In each case, the retailer involved and the UK Food Standards Agency were immediately informed, and full investigations were undertaken. Nineteen cases of Salmonella Newport PT33 infection were subsequently identified throughout England and Wales. The outbreak strain of Salmonella Newport PT33 isolated from the salad and from humans had a unique plasmid profile. Campylobacter spp. and E. coli O157 were not detected in any of the samples examined. The presence of Salmonella, as well as high levels of L. monocytogenes, is unacceptable. However, minimally processed cut and packaged salad is exposed to a range of conditions during growth, harvest, preparation, and distribution, and it is possible that these conditions may increase the potential for microbial contamination, highlighting the necessity for the implementation of good hygiene practices from farm to fork to prevent contamination and/or bacterial growth in these salad products.     

Microbiological quality of 18 degrees C ready-to-eat food products sold in Taiwan

A total of 164 samples of 18 °C ready-to-eat (RTE) food products, purchased in 1999–2000 from convenience stores and supermarkets in central Taiwan, were examined to determine the microbiological quality of these products. The 18 °C RTE food products, manufactured by 16 factories, were divided into groups based on the type of food and their major ingredients. Aerobic plate count, coliforms, Escherichia coli, Bacillus cereus, Staphylococcus aureus and psychrotrophic Pseudomonas spp. were evaluated. The incidence of E. coli and coliforms in these 18 °C RTE food products was 7.9% and 75.0%, respectively, while 49.8% and 17.9% of the samples were found to contain B. cereus and S. aureus, respectively. Among the samples tested, 1.3% of the food products contained more than 10⁵ CFU g⁻¹ of B. cereus and 0.7% contained more than 10⁵ CFU g⁻¹ of S. aureus. The pH values of the samples were all below 7.0, except for cold noodles, which had pH values ranging from 5.18 to 8.20. Among the five types of 18 °C food products tested, the highest incidence of E. coli (16%) and Pseudomonas spp. (64.0%) were detected in hand-rolled sushi in a cone shape. On the other hand, the highest incidence rate of coliforms, B. cereus, and S. aureus were found in sandwiches (88%), cold noodles (66.7%) and rice balls rolled in seaweed (25.0%), respectively. Food products made of ham contained the highest incidence of coliforms (88.0%) and E. coli (16.0%), while food products containing meat and ham as the major ingredients had the highest incidence rates of B. cereus (62.5%) and S. aureus (26.1%), respectively. For coliforms, E. coli, B. cereus and S. aureus, the percentage of 18 °C RTE food products exceeding the microbiological standards for RTE food accepted by Republic of China was 75.0%, 7.9%, 49.8% and 17.9%, respectively.     

Microbiological safety of ready-to-eat minimally processed vegetables in Brazil: an overview

The market of ready-to-eat minimally processed vegetables (RTE-MPV) is increasing in Brazil and many other countries. During processing, these vegetables go through several steps that modify their natural structure while maintaining the same nutritional and sensory attributes as the fresh produce. One of the most important steps is washing-disinfection, which aims to reduce the microbial load, prevent cross-contamination and inactivate pathogenic microorganisms that may be present. Nonetheless, the presence of pathogens and occurrence of foodborne illnesses associated with consumption of RTE-MPV concern consumers, governments and the food industry. This review brings an overview on the microbiological safety of RTE-MPV, focusing on Brazilian findings. Most of the published data are on detection of Salmonella spp. and Listeria monocytogenes, indicating that their prevalence may range from 0.4% to 12.5% and from 0.6% to 3.1%, respectively. The presence of these pathogens in fresh produce is unacceptable and risky, mainly in RTE-MPV, because consumers expect them to be clean and sanitized and consequently safe for consumption without any additional care. Therefore, proper control during the production of RTE-MPV is mandatory to guarantee products with quality and safety to consumers. © 2020 Society of Chemical Industry     

Microbiological quality and shelf life modeling of ready-to-eat cicorino

Growth of the microbial population resident in ready-to-use fresh cut cicorino, a variety of Chichorium intybus, was determined in the various preparation steps with the aim of defining the hazard critical control points. The investigation concerned cut cicorino from two producers. During the process a 1- to 1.5-fold increase of microbial counts was observed, and the retail product showed values of 10(5) to 10(6) CFU/g. The shelf life of the product was kinetically modeled in order to check the effects of storage temperature and assess the microbial indexes most relevant for hygiene and quality of the distributed product. A modified Gompertz function described the kinetics of microbial growth and allowed definition of a stability time and its dependence on temperature. Stability times were of 0.3, 3.7, and 4.7 days at storage temperatures of 20, 10, and 5 degrees C, respectively. Q10 (the fold decrease of stability time for an increase of 10 degrees C) was 3.85. The results from this study may be used to predict the effects of temperatures experienced in the distribution chain on bacterial levels in cicorino.     

Microbiological water quality requirements for salad irrigation in the United Kingdom

The growth in United Kingdom salad production is dependent on irrigation to maintain product quality. There are concerns that irrigation with poor-quality water could pose a disease risk. This article examines the key issues in the emerging debate on the microbiological quality of water used for salad irrigation in the United Kingdom. The links between irrigation water quality and foodborne disease, and the current international guidance on irrigation water quality, are firstly reviewed. The findings indicate that a number of recent food-poisoning outbreaks have been linked to the consumption of fresh fruits and vegetables and that unhygienic product handling is implicated as the principal source of contamination. There is also credible evidence that salads contaminated in the field, including by irrigation water, can pose a small disease risk at the point of sale. Although irrigation water-quality standards exist in various forms internationally, there is no nationally agreed on standard used in the United Kingdom. This paper then describes the results of a survey conducted in 2003 of United Kingdom irrigation practices that might influence the microbiological quality of salads. The survey showed that surface water is the principal irrigation water source, that overhead irrigation predominates, that the gap between the last irrigation and harvest may be < 24 h in many cases, and that current water-quality monitoring practices are generally very limited in scope. This paper concludes with a discussion of the issues emerging from the review and survey, including the need for improved water-quality monitoring, and the problems associated with establishing water-quality standards that could be either too strict or too lax.     

Effect of Cold Atmospheric Plasma processing on quality and shelf-life of ready-to-eat rocket leafy salad

The effect of Cold Atmospheric Plasma (CAP) on ready-to-eat (RTE), fresh cut, leafy rocket salad (ready-to-eat arugula leaves packed in pouches of 125 g) was investigated, aiming at quality retention and shelf-life extension. CAP was generated via a surface dielectric barrier discharge source and its efficiency on rocket leaves was evaluated at different processing times through microbial, texture, pH value and colour analyses. A reduction of 0.57 to 1.02 log CFU/g was observed for the total microbial load after processing times ranging from 5 to 20 min, respectively. A CAP processing time of 10 min was considered as optimum, for a sufficient reduction of the microbial load while maintaining colour and texture. The shelf-life of the optimum CAP-processed rocket stored at 2-9 °C was estimated through analysis of specific quality parameters. Pseudomonas spp. growth (higher count of approximately 7.0 log CFU/g) was considered to be the dominant deterioration factor. The shelf-life of the CAP-treated leafy rocket salad was estimated as 116, 84 and 55 h compared to 63, 57 and 37 h for the control samples after storage at 2, 5 and 9 °C, respectively.Industrial relevanceSpoilage of fresh-cut vegetables due to microbial growth has a significant economic impact causing food waste by reducing the shelf-life of the products and posing a risk for the public health through possible foodborne illnesses. As a result, there is a real need to seek for alternative methods for preservation of fresh produce. Cold Atmospheric Plasma technology could potentially be applied for microbial load reduction of leafy salads. The proposed protocol along with the device used for Surface Dielectric Barrier Discharge treatment, could be a potential solution for extending the shelf-life of significantly perishable fresh produce.     

Bacterial contamination in the environment of food factories processing ready-to-eat fresh vegetables.

A total of 196 samples were collected from equipment for trimming, washing, slicing, soaking, dehydrating, blending, and packaging and from the floor and air of operation rooms before and after operation in two food factories processing ready-to-eat fresh vegetables located in the suburbs of Tokyo. Heavy contamination determined by an aerobic plate count of >5.0 log CFU/cm2 or ml was observed after operation in most of the samples examined, as were samples taken before operation on the interior surfaces of equipment for washing, slicing, dehydrating, and blending, the surfaces of blades for slicing, and the floor surfaces of operation rooms. From these environmental samples, the coliform group was detected before operation. Although 67 strains of 70 coliforms isolated were nonfecal, three Escherichia coli strains were detected in the surface of the operation room floors and the gloves of employees. Bacillus cereus was isolated from 9 of 86 and 17 of 85 samples examined before and after operation with the number of 2.0 to 3.0 log CFU/cm2 or ml. Listeria spp. were not detected in the environment of the food factories.     

Impact of different temperature abuse scenarios on sensory quality and off-odour formation in ready-to-eat salad leaves

Packages of ready-to-eat (RTE) wild rocket and lettuce baby leaves were subjected during 8 days of cold storage to a chronic temperature abuse (CTA) at sub-optimal storage temperature (10 °C) or to a short-term (6 h) abuse at ambient temperature (STA) to evaluate the impact of two temperature abuse scenarios on gas composition within the packages, leaf sensory quality and volatile organic compounds (VOCs). In both species, the CTA scenario had a markedly higher impact on gas composition, sensory quality and off-odour formation than the STA, and the limit of sensory acceptability was reached in the CTA scenario 4 days or more earlier than in the STA. Sulphur compounds were the main responsible for off-odour perception in both leafy salads. Results from the present study may be useful in the assessment of critical points in the cold chain of RTE fresh produce and in prioritising actions towards improved cold-chain management.     

Microbiological quality and safety of ready-to-eat street-vended foods in Johannesburg, South Africa

Fifty-one ready-to-eat street foods, 18 dishwater, and 18 surface swab samples were collected from six vendors in Johannesburg, South Africa. Food temperatures were recorded at the time of sampling. Standard methods were used to determine aerobic plate counts (APCs), spore counts (SCs), and Enterobacteriaceae counts (ECs) for food samples as well as coliform counts (CCs) for water and swab samples. In addition, Petrifilm Escherichia coli count (PC) plates were used for the enumeration of coliforms in food, water, and swab samples. The presence of selected foodborne pathogens in the food samples as well as the presence of nonpathogenic E. coli 1 (in food and water samples) was also tested for. Predominant colonies isolated from APC plates were characterized to the genus level. Holding temperatures for cooked meats and gravies ranged from 42.0 to 94.0 degrees C, and those for uncooked salads ranged from 29.0 to 39.0 degrees C. Mean APC values of 3.4 (+/-0.4) log CFU/g, 4.0 (+/-1.2) log CFU/ml, and 2.1 (+/-0.4) log CFU/25 cm2 were obtained for food, water, and swab samples, respectively. Mean SC values of 1.6 (+/-0.2) log CFU/g and 1.5 (+/-0.3) log CFU/25 cm2 were obtained for food and swab samples, respectively. A mean EC value of 2.0 (+/-0.4) log CFU/g for food samples and mean CC values of 2.5 (+/-0.3) log CFU/ml and 1.3 (+/-0.3) log CFU/25 cm2 for water and swab samples, respectively, were determined. Mean PC values of 1.6 (+/-0.1) log CFU/g, 1.9 (+/-0.6) log CFU/ml, and 1.4 (+/-0.4) log CFU/25 cm2 were determined for food, water, and swab samples, respectively. Bacillus cereus was detected in 22%, Clostridium perfringens in 16%, Salmonella spp. in 2%, and E. coli (non-O157:H+) in 2% of the 51 food samples. E. coli was found in 14 water samples (78%) and in 3 food samples (6%). Campylobacter spp., Listeria monocytogenes, Staphylococcus aureus, Vibrio cholerae, and Yersinia enterocolitica were also tested for in the food samples, but they were not detected. The 340 isolates obtained from APC plates for food, water, and swab samples were predominantly Bacillus spp., Micrococcus spp., and Staphylococcus spp. for all three sample types. It was concluded that the foods analyzed in this study were of acceptable quality and safety.     

Inactivation of foodborne pathogens in ready-to-eat salad using UV-C irradiation

To examine the applicability of ultraviolet (UV)-C irradiation on the inactivation of foodborne pathogen in ready-to-eat salad, it was inoculated with Escherichia coli O157:H7 and Listeria monocytogenes and then irradiated with UV-C light. Radiation dose required for 90% reduction (d _R) values of E. coli O157:H7 and L. monocytogenes were determined to be 0.21 and 2.48 J/m², respectively. Foodborne pathogen populations significantly (p<0.05) decreased with increasing UV-C irradiation. UV-C irradiation at 8,000 J/m² reduced the populations of E. coli O157:H7 and L. monocytogenes on ready-to-eat salad by 2.16 and 2.57 log CFU/g, respectively.     

Microbiological quality of ready-to-eat foods: results from a long-term surveillance program (1995 through 2003)

The coordination of food sampling activities across Wales, a part of the United Kingdom with a population of approximately 3 million, led to the establishment in 1995 of a coordinated food-sampling program designed to monitor on a long-term basis the microbiological quality and safety of specific ready-to-eat products. This surveillance system has been ongoing for 9 years and has generated a database of microbiological and associated demographic results for 15,228 ready-to-eat food samples. The food types that had the poorest overall results were sliced meats, unsliced poultry, sandwiches made without salad, and cakes made without dairy cream. For all food types, the overall unsatisfactory rate was 17% for aerobic colony counts, 1.6% for Escherichia coli, and 0.5% for Listeria spp. Overall unsatisfactory or unacceptable rates for pathogens such as Clostridium perfringens, Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus were all below 0.5%. No Campylobacter-positive samples and only one Salmonella-positive sample were found. The analysis of the results show that the ready-to-eat food types sampled over the 9 years of the program were generally of good microbiological quality when compared with current United Kingdom guidelines. The information contained in the database provides a baseline measurement of the microbial quality of a variety of ready-to-eat foods and allows environmental health officers and food microbiologists to generate hypotheses for targeted surveys or research work.     

Thermal pasteurization of ready-to-eat foods and vegetables: Critical factors for process design and effects on quality

Increasing consumer desire for high quality ready-to-eat foods makes thermal pasteurization important to both food producers and researchers. To be in compliance with the Food Safety Modernization Act (FSMA), food companies seek regulatory and scientific guidelines to ensure that their products are safe. Clearly understanding the regulations for chilled or frozen foods is of fundamental importance to the design of thermal pasteurization processes for vegetables that meet food safety requirements. This article provides an overview of the current regulations and guidelines for pasteurization in the U.S. and in Europe for control of bacterial pathogens. Poorly understood viral pathogens, in terms of their survival in thermal treatments, are an increasing concern for both food safety regulators and scientists. New data on heat resistance of viruses in different foods are summarized. Food quality attributes are sensitive to thermal degradation. A review of thermal kinetics of inactivation of quality-related enzymes in vegetables and the effects of thermal pasteurization on vegetable quality is presented. The review also discusses shelf-life of thermally pasteurized vegetables.     

Microbiological quality and safety of ready-to-eat cooked foods from a centralized school kitchen in Argentina

The purpose of this study was to evaluate the microbiological and sensory quality as well as the safety of ready-to-eat (RTE) cooked foods prepared in and distributed from a centralized kitchen to schools in Argentina. A total of 101 cooked food samples delivered as hot RTE cooked foods (group A) and as RTE cooked foods at room temperature (group B) and 140 surface swab environment samples were collected from February to November 1999. Petrifilm plates were used for aerobic (PAC), coliform (PCC), and Escherichia coli (PEC) counts. Standard methods were used to determine Enterobacteriaceae (EntC) and thermotolerant coliform counts (TCC). Samples were also tested for the presence of Salmonella spp., Staphylococcus aureus, Bacillus cereus, and Clostridium perfringens. Food temperatures just before samples were put into containers ranged from 80 to 98 degrees C and from 28 to 32 degrees C for group A and group B, respectively. For group A food samples, PAC ranged from 1.04 to 3.50 log CFU/g, and PCC, PEC, TCC, and EntC were not detected. For group B food samples, PAC ranged from 3.63 to 6.48 log CFU/g, PCC ranged from 1.90 to 5.36 log CFU/g, TCC ranged from 1.30 to 3.95 log CFU/g, and EntC ranged from 3.60 to 5.46 log CFU/g. Of the foodborne pathogens, only B. cereus was isolated (63.4% of samples) in both food groups (<4 log CFU/g). The microbiological and sensory quality and the safety of group A foods were satisfactory. Large numbers of PAC and EntC detected in group B foods show that better control is needed to avoid potential foodborne diseases.     

Survival of poliovirus on soft fruit and salad vegetables

A series of studies were performed, using poliovirus, to ascertain the potential for enteric pathogenic viruses to survive on various foodstuffs. The extraction protocols, which could be performed in just a few hours, were developed for use with quantities of food that would normally constitute a portion for consumption. The protocols were based on elution of viruses from food surfaces, followed by differential centrifugation to remove food debris and concentrate viruses. The studies were mostly performed using fresh produce stored at refrigeration temperature for 2 weeks or so, which was considered to represent the maximum time elapsing between purchase and consumption. Each food sample was inoculated with a viral suspension, and samples were analyzed immediately and at intervals throughout the experiment. Statistical analyses were performed on the results, and the decimal reduction times (D-values), or number of days after which the initial virus numbers had declined by 90%, were calculated. In summary, the resulting D-values were as follows: lettuce, 11.6 days; green onion, no decline; white cabbage, 14.2 days; fresh raspberries, no decline; and frozen strawberries, 8.4 days. The results showed that enteric viruses may persist on fresh fruit and vegetables for several days under conditions commonly used for storage in households. Therefore, if contamination has occurred before purchase, there will always be a risk of infection from consumption of the food.     

A training course on food hygiene for butchers: measuring its effectiveness through microbiological analysis and the use of an inspection checklist

The effectiveness of food hygiene training for a group of retail butchers was evaluated with the aim of verifying whether the butchers modified their behavior in the light of knowledge gained and whether their acquired knowledge or behavior change was sustained over a period of time. Microbiological analysis (enumeration of mesophilic and coliform bacteria and Escherichia coli) of a raw semiprocessed product (stuffed rolled beef) was conducted, and an inspection checklist was issued before the training course (T0). Initial results were later compared with results obtained 1 month (T1) and 6 months (T6) after the training. The checklist comprised 89 items classified into five categories: A, approved suppliers and product reception; B, storage conditions and temperature control; C, flow process, food handling procedures, and conditions of the window display unit; D, facility design and proper cleaning and sanitizing of equipment, utensils, and work surfaces; and E, pest control system, water supply control, and garbage disposal. The inspection results were recorded as "yes" or "no" for each item. Compliance with food safety procedures was recorded as the percentage of "yes" answers. The bacterial counts were significantly higher at T0. At T6, there was no significant increase in bacterial counts. There was a significant improvement in food safety practices at T1 and T6 compared with T0 for all categories. When comparing T0 and T1, the largest increases in the compliance scores were seen within categories C and D. No significant decrease in scores for compliance with food safety practices was observed at T6. Supervision and refresher activities may be necessary to maintain behavioral changes for a longer period of time.     

Meta-analysis of food safety training on hand hygiene knowledge and attitudes among food handlers

Research has shown that traditional food safety training programs and strategies to promote hand hygiene increases knowledge of the subject. However, very few studies have been conducted to evaluate the impact of food safety training on food handlers' attitudes about good hand hygiene practices. The objective of this meta-analytical study was to assess the extent to which food safety training or intervention strategies increased knowledge of and attitudes about hand hygiene. A systematic review of food safety training articles was conducted. Additional studies were identified from abstracts from food safety conferences and food science education conferences. Search terms included combinations of "food safety," "food hygiene," "training," "education," "hand washing," "hand hygiene," "knowledge," "attitudes," "practices," "behavior," and "food handlers." Only before- and after-training approaches and cohort studies with training (intervention group) and without training (control group) in hand hygiene knowledge and including attitudes in food handlers were evaluated. All pooled analyses were based on a random effects model. Meta-analysis values for nine food safety training and intervention studies on hand hygiene knowledge among food handlers were significantly higher than those of the control (without training), with an effect size (Hedges' g) of 1.284 (95% confidence interval [CI] ～ 0.830 to 1.738). Meta-analysis of five food safety training and intervention studies in which hand hygiene attitudes and self-reported practices were monitored produced a summary effect size of 0.683 (95% CI ～ 0.523 to 0.843). Food safety training increased knowledge and improved attitudes about hand hygiene practices. Refresher training and long-term reinforcement of good food handling behaviors may also be beneficial for sustaining good hand washing practices.     

Microbiological quality of randomly selected ready-to-eat foods sampled between 2003 and 2005 in Wales, UK

Since 1995, the publicly funded ready-to-eat food sampling and examination activities in Wales have been coordinated and structured, using a novel approach for the identification of samples and premises. The latest set of data from this surveillance system reports the results from 3391 ready-to-eat foods sampled between November 2003 and March 2005. During this seventeen-month period all samples were examined for aerobic colony count, Escherichia coli, Listeria spp., Bacillus cereus, Salmonella, Staphylococcus aureus and Listeria monocytogenes. The food types with the poorest microbiological quality were cream cakes, custard slices and egg mayonnaise sandwiches. The food type with the best microbiological quality was dried fruit. In conclusion, the results indicate that, in general terms, the ready-to-eat food types sampled and examined in this period posed little bacterial hazard to consumers.     

Microbiological performance of a food safety management system in a food service operation

The microbiological performance of a food safety management system in a food service operation was measured using a microbiological assessment scheme as a vertical sampling plan throughout the production process, from raw materials to final product. The assessment scheme can give insight into the microbiological contamination and the variability of a production process and pinpoint bottlenecks in the food safety management system. Three production processes were evaluated: a high-risk sandwich production process (involving raw meat preparation), a medium-risk hot meal production process (starting from undercooked raw materials), and a low-risk hot meal production process (reheating in a bag). Microbial quality parameters, hygiene indicators, and relevant pathogens (Listeria monocytogenes, Salmonella, Bacillus cereus, and Escherichia coli O157) were in accordance with legal criteria and/or microbiological guidelines, suggesting that the food safety management system was effective. High levels of total aerobic bacteria (>3.9 log CFU/50 cm(2)) were noted occasionally on gloves of food handlers and on food contact surfaces, especially in high contamination areas (e.g., during handling of raw material, preparation room). Core control activities such as hand hygiene of personnel and cleaning and disinfection (especially in highly contaminated areas) were considered points of attention. The present sampling plan was used to produce an overall microbiological profile (snapshot) to validate the food safety management system in place.     

Presence of Trihalomethanes in ready-to-eat vegetables disinfected with chlorine

ABSTRACT

Trihalomethanes (THMs) – CHCl₃, CHCl₂Br, CHClBr₂ and CHBr₃ – are drinking water disinfection by-products (DBPs). These compounds can also be absorbed by different types of foods, including ready-to-eat (RTE) fresh vegetables. The potential absorption of THMs during washing of RTE vegetables could pose a potential risk to consumers’ health. The concentration of THMs in the water used in the manufacturing process of these products shall not exceed the limit of 100 or 80 µgL^?1 according to European Union (EU) and United States legislation, respectively. By contrast, there is little information about the presence of such compounds in the final product. This study evaluated the concentration of THMs in different types of RTE vegetables (carrots, iceberg lettuce, lettuce, mixed salad, parsley, parsley and garlic, rocket salad, valerian) after washing with chlorinated water. In the 115 samples analysed, the average value of total THMs was equal to 76.7 ng g^?1. Chloroform was the THM present in the largest percentage in all the RTE vegetables. These results show that the process of washing RTE vegetables should be optimised in order to reduce the risk for consumers associated with the presence of DBPs.     

Pesticides as a source of microbial contamination of salad vegetables

Ten commercially available pesticides (insecticides, herbicides and fungicides), used during the production of vegetable produce, were examined as potential sources of microbial contaminants. As purchased, none of the pesticides showed the presence of viable microorganisms (< 5 CFU/ml). Using an agar plate diffusion assay, they did not inhibit a range of bacteria of spoilage and public health significance on vegetable produce. After reconstitution in sterile water to their recommended concentration, two of the pesticides supported the survival and growth of inoculated species of Pseudomonas, Salmonella and Escherichia coli. Listeria monocytogenes did not survive after inoculation into any of the pesticides. Pesticides were reconstituted in different sources of agricultural water (bore, dam and river) and examined for survival and growth of microorganisms naturally present in these waters. On storage at 30 degrees C for 48 h, nine of the pesticides supported the growth of bacterial species present in these waters. Predominant species in the pesticide solutions, before and after storage, varied according to the source, but species of Pseudomonas, Acinetobacter and Aeromonas and various coliforms exhibited significant growth. Unless managed properly (reconstituted in potable water, and used without lengthy storage), pesticides could contribute to the microbial load of vegetable produce, thereby affecting their shelf-life and public health safety.