A comparison of DNA repair and survival of Escherichia coli O157:H7 following exposure to both low- and medium-pressure UV irradiation

DNA repair and survival of pathogenic E. coli O157:H7 was investigated following exposure to ultraviolet (UV) radiation from both low-pressure (LP) and medium-pressure (MP) lamps. This study included irradiation at UV doses used in drinking water treatment and lower doses indicative of potential treatment problems. Immediately following UV exposure, an average log inactivation of 4.5 or greater was observed following all tested doses of LP (5, 8, 20 and 40 mJ/cm²) or MP UV (5 and 8 mJ/cm²) indicating the sensitivity of E. coli O157:H7 to UV irradiation. Following conditions conducive to repair, maximum photo repair occurred rapidly within 30 minutes after low doses (5 and 8 mJ/cm²) of LP UV. The rate of repair was much higher than reported previously in non-pathogenic E. coli (which occurred within 2 hours). In contrast to LP UV, limited photo repair of E. coli O157:H7 was observed following MP UV exposure at reduced doses (5 and 8 mJ/cm²). At these lower doses, low levels of light independant repair were observed following LP UV, but not following exposure of MP UV irradiation. This study indicates that MP UV may enhance UV disinfection of E. coli O157:H7 by reducing the ability to repair following non-ideal treatment conditions. Following doses used in drinking water treatment (20 and 40 mJ/cm²), low levels of photo repair following LP UV were evident.     

Comparative removal of antibiotic resistance genes during chlorination,ozonation, and UV treatment

Efficient treatment methods for the removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from drinking water are needed to reduce health risks. However, there is a lack of empirical data on ARB and ARG removal during conventional water disinfection processes. In this study, the removal of ARB and ARGs by three disinfection processes (chlorination, ozonation, and UV treatment) was investigated on a laboratory scale using Escherichia coli and Enterococcus faecium carrying ARGs. Bacterial inactivation was determined by plate count methods, and ARG damage was quantified using real-time PCR. Only for ozone treatment, similar inactivation rates for bacterial cells and ARGs were observed when 1 mg*L^?1 of ozone, with a contact time of 5 min, was used, which resulted in a 5.0 log reduction of bacterial cells and a 4.3–4.6 log reduction of ARGs. For chlorine and UV, inactivation of bacterial cells was observed at lower doses than those needed for the decrease of ARG copy numbers. The use of 0.5 mg*L^?1 free chlorine (30 min contact time) led to a 3.8–5.6 log reduction of the bacterial numbers and to a 0.8–2.8 log reduction of ARGs. Ultraviolet light irradiation with 600 J*m^?2 resulted in a 4.8–5.5 log reduction of bacterial cells, but in a negligible reduction (0–1.0 log) of ARGs. Although UV and chlorine treatments were effective in the inactivation of bacterial cells, incomplete degradation of ARGs was observed. Therefore, plasmid-borne ARGs can potentially be transferred to other bacteria even after the disinfection process. Our results provide important insights into the fate of ARGs during drinking water disinfection processes.     

Effectiveness of UV-C light irradiation on disinfection of an eSOS® smart toilet evaluated in a temporary settlement in the Philippines

Ultraviolet germicidal (short wavelength UV-C) light was studied as surface disinfectant in an Emergency Sanitation Operation System^® smart toilet to aid to the work of manual cleaning. The UV-C light was installed and regulated as a self-cleaning feature of the toilet, which automatically irradiate after each toilet use. Two experimental phases were conducted i.e. preparatory phase consists of tests under laboratory conditions and field testing phase. The laboratory UV test indicated that irradiation for 10 min with medium–low intensity of 0.15–0.4 W/m² could achieve 6.5 log removal of Escherichia coli. Field testing of the toilet under real usage found that UV-C irradiation was capable to inactivate total coliform at toilet surfaces within 167-cm distance from the UV-C lamp (UV-C dose between 1.88 and 2.74 mW). UV-C irradiation is most effective with the support of effective manual cleaning. Application of UV-C for surface disinfection in emergency toilets could potentially reduce public health risks.     

Inactivation of human adenovirus by sequential disinfection with an alternative UV technology and free chlorine

There has been growing concern over human exposure to adenoviruses through drinking water due to the extreme resistance of human adenoviruses to the traditional UV technology (low-pressure (LP) UV). As an effort to develop an effective treatment strategy against human adenoviruses in drinking water, we determined the effectiveness of sequential disinfection with an alternative UV technology (medium-pressure (MP) UV) and free chlorine. Human adenovirus 2 (Ad2) was irradiated with a low dose of MP UV irradiation (10 mJ/cm²) through UV collimated apparatus and then exposed to a low dose of free chlorine (0.17 mg/L) at pH 8 and 5°C using a bench-scale chemical disinfection system. A significant inactivation (e.g. 4 log₁₀) of Ad2 was achieved with the low doses of MP UV and free chlorine within a very short contact time (~1.5 min) although there was no apparent synergistic effect on Ad2 between MP UV and free chlorine. Overall, it is likely that the sequential disinfection with UV irradiation and free chlorine should control the contamination of drinking water by human adenoviruses within practical doses of UV and free chlorine typically used in drinking water treatment processes.     

The effect of UV-C radiation (254 nm) on candidate microbial source tracking phages infecting a human-specific strain of Bacteroides fragilis (GB-124)

The enumeration of phages infecting host-specific strains of Bacteroides has been widely recognised as an effective and low-cost method of microbial source tracking (MST). A recently described human-specific Bacteroides host strain (GB-124) has been shown to detect bacteriophages exclusively in human-impacted waters and is emerging as a useful MST tool. However, a better understanding of the morphology and ecological behaviour of the phages, especially in wastewater disinfection processes, is now required in order to validate their role as MST markers. Bacteriophages infecting Bacteroides fragilis GB-124 (n = 21) were isolated from wastewater effluent and irradiated using laboratory-based UV-C (254 nm) collimated beam experiments. Bacteriophages were found to be both a morphologically and ecologically homogeneous group, with all specimens showing highly similar first order log-linear inactivation profiles (mean fluence required to inactivate phages by 4-log(10) was 36 mJ/cm(2)). These findings present the first evidence that phages infecting GB-124 are inactivated by the levels of UV-C radiation routinely delivered during tertiary wastewater treatment processes. More importantly, comparison with previously published inactivation data suggests that their response to UV-C radiation makes GB-124 phages more suitable surrogates for selected enteric viruses in UV disinfection processes than traditional faecal indicator bacteria or human-specific molecular markers.     

UV disinfection of soluble oil metalworking fluids

The efficacy of a new high-intensity germicidal ultraviolet (UV) lamp for disinfection of opaque metalworking fluids (MWF) was investigated under laboratory conditions. Three dilutions of "soluble oil" MWF and water controls in a circulating system were inoculated with suspensions of Pseudomonas fluorescens to an initial concentration of about 10(7) colony forming units (CFU) per milliliter and irradiated with a submerged nonglass UV lamp. Aliquots of the circulating fluid were withdrawn before irradiation and at 10-sec intervals in the water control and 10-min intervals in the MWF. The samples were diluted with sterile water, plated, and counted after 18-24 hours' incubation. The UV-C radiation output of the lamp was estimated by irradiance measurements using a research radiometer. The concentration of CFU decreased by at least 2 logs (>99% reduction in culturability) in 30 sec in irradiated water. In all three dilutions of MWF, a 2-log decrease was obtained within 60 min. The UV-C output of the lamp was estimated at about 6 W. The disinfection appeared to follow a first order rate law both in MWF and in water. The CFU concentration was stable over time in unirradiated controls. These results demonstrate that UV disinfection is feasible in MWF opaque to both visible and UV wavelengths of light.     

Decolonization of Staphylococcus aureus carriage

Staphylococcus aureus nasal colonization is a well-known independent risk factor for infection caused by this bacterium. Screening and decolonization of carriers have been proven effective in reducing S. aureus infections in some populations. However, a gap remains between what has been proven effective and what is currently done. We aimed to summarize recommendations and current knowledge of S. aureus decolonization to answer the following questions: Why? For whom? How? When? And what are the perspectives?     

Efficacy of phytol-derived diterpenoid immunoadjuvants over alum in shaping the murine host's immune response to Staphylococcus aureus

The ubiquitous gram-positive bacterium Staphylococcus aureus occupies a unique niche in humans for its ability to survive both as a commensal and a life-threatening pathogen. Its complex relationship with the host and its ability to engender a throng of virulence factors, have hindered the development of a successful vaccine against it. The use of immunoadjuvants to enhance host immunity and prevent the shift from commensalism to pathogenicity is a rational approach for containing infection. The objective of this study was to understand the mechanisms by which alum and two phytol-derived immunoadjuvants, phytanol (PHIS-01) ¹ and phytanyl chloride (PCl) ² shape the interaction between S. aureus and its murine host. We studied the effects of the phytol derivatives, relative to alum, on the induction of inflammatory cytokines and chemokines, recruitment of CD11b⁺ cells, generation of specific anti-S. aureus antibodies and in vitro clearance of S. aureus. Our results showed that both PHIS-01 and PCl were stronger inducers of protective cytokines IL-17 and IL-1β than alum, and far exceeded alum in enhancing anti-S. aureus antibody response. However, both alum and the phytol derivatives (particularly PCl) promoted efficient recruitment of CD11b⁺ cells. Furthermore, PHIS-01, alum and to a lesser extent, PCl were able to up-regulate the expression of key inflammation-related genes that were highly down-regulated by S. aureus alone. In vitro killing assays showed that both PHIS-01 and PCl were far more potent than alum in promoting S. aureus clearance; this indicated their efficiency in shaping an effective anti-S. aureus immune microenvironment. In summary, our study provides evidence for the better effectiveness of phytol-derived immunoadjuvants over alum in enhancing anti-S. aureus immunity.     

Evolution of community- and healthcare-associated methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is a prominent cause of human infections globally. The high prevalence of infections is compounded by antibiotic resistance—a significant problem for treatment. Methicillin-resistant S. aureus (MRSA) is endemic in hospitals and healthcare facilities worldwide, and is an increasingly common cause of community-associated bacterial infections in industrialized countries. Although much focus is placed on the role of S. aureus as a human pathogen, it is in fact a human commensal organism that has had a relatively long coexistence with the human host. Many S. aureus infections can be explained by host susceptibility or other predisposing risk factors. On the other hand, the emergence/re-emergence of successful S. aureus clones (referred to as epidemic waves) suggests a rapid bacterial adaption and evolution, which includes the emergence of antibiotic resistance and increased virulence and/or transmissibility. It is within this context that we review our understanding of selected S. aureus epidemic waves, and highlight the use of genome sequencing as a means to better understand the evolution of each lineage.     

Determination of Bioaccumulation of Heavy Metals and Selenium in Tissues of Brown Trout Salmo trutta macrostigma (Duméril, 1858) from Munzur Stream, Tunceli, Turkey

The objective of the present work was to determine the bioaccumulation of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), uranium (U) and selenium (Se) in gill, liver, and muscle tissues of the fresh water fish Salmo trutta macrostigma (Duméril, 1858) in Munzur Stream, Tunceli, Turkey. The highest concentrations of U (1.83?μg?kg^?1), Pb (119.84?μg?kg^?1) and Se (1.31?μg?kg^?1) were recorded in the gills of S. t. macrostigma. Concentrations of As (46.27?μg?kg^?1), Cd (109.19?μg?kg^?1), Hg (16.40?μg?kg^?1), Cu (18.19?μg?kg^?1) were recorded at highest levels in the liver. The results showed that there were significant differences in concentrations of As, Cd, Cu, Pb, Se, U and Hg in gill, liver and muscle tissue (p?<?0.05). Heavy metals were within the edible parts of the investigated fish were in the permissible safety levels for human uses.     

Reduction of spiked porcine circovirus during the manufacture of a Vero cell-derived vaccine

Porcine circovirus-1 (PCV1) was recently identified as a contaminant in live Rotavirus vaccines, which was likely caused by contaminated porcine trypsin. The event triggered the development of new regulatory guidance on the use of porcine trypsin which shall ensure that cell lines and porcine trypsin in use are free from PCV1. In addition, manufacturing processes of biologicals other than live vaccines include virus clearance steps that may prevent and mitigate any potential virus contamination of product. In this work, artificial spiking of down-scaled models for the manufacturing process of an inactivated pandemic influenza virus vaccine were used to investigate inactivation of PCV1 and the physico-chemically related porcine parvovirus (PPV) by formalin and ultraviolet-C (UV-C) treatment as well as removal by the purification step sucrose gradient ultracentrifugation. A PCV1 infectivity assay, using a real-time PCR infectivity readout was established. The formalin treatment (0.05% for 48 h) showed substantial inactivation for both PCV1 and PPV with reduction factors of 3.0 log₁₀ and 6.8 log₁₀, respectively, whereas UV-C treatment resulted in complete PPV (≥5.9 log₁₀) inactivation already at a dose of 13 mJ/cm but merely 1.7 log₁₀ at 24 mJ/cm² for PCV1. The UV-C inactivation results with PPV were confirmed using minute virus of mice (MVM), indicating that parvoviruses are far more sensitive to UV-C than PCV1. The sucrose density gradient ultracentrifugation also contributed to PCV1 clearance with a reduction factor of 2 log₁₀. The low pH treatment during the production of procine trypsin was investigated and showed effective inactivation for both PCV1 (4.5 log₁₀) and PPV (6.4 log₁₀). In conclusion, PCV1 in general appears to be more resistant to virus inactivation than PPV. Still, the inactivated pandemic influenza vaccine manufacturing process provides for robust virus reduction, in addition to the already implemented testing for PCV1 to avoid any contaminations.     

Methicillin-Susceptible,Vancomycin-Resistant Staphylococcus aureus,Brazil

We report characterization of a methicillin-susceptible, vancomycin-resistant bloodstream isolate of Staphylococcus aureus recovered from a patient in Brazil. Emergence of vancomycin resistance in methicillin-susceptible S. aureus would indicate that this resistance trait might be poised to disseminate more rapidly among S. aureus and represents a major public health threat.     

Vaccination as infection control: A pilot study to determine the impact of Staphylococcus aureus vaccination on nasal carriage

Background

There is a critical need for an effective Staphylococcus aureus vaccine for the prevention of staphylococcal disease. In this study, we investigated the impact of S. aureus conjugate vaccine comprised of capsular polysaccharides 5 and 8 (CP5, CP8) on nasal colonization with S. aureus.

Methods

Healthy adults recruited from one academic medical center to participate in a lot consistency trial of StaphVAX^® (S. aureus capsular polysaccharide 5 and 8 conjugate vaccine) were assessed for S. aureus nasal colonization at two weekly points prior to vaccination and again at six weeks post-vaccination. Serum anti-capsular antibody titers to CP5 and CP8 were obtained prior to vaccination and 42 days post-vaccination and measured by ELISA.

Results

Thirty of 88 enrolled subjects (34%) had S. aureus isolated from at least one of the pre-immunization cultures. Of these, 20 were termed persistent carriers due to two positive cultures one week apart; 19 of the 20 were evaluable at Day 42. Baseline anti-CP8 concentrations were higher in persistent carriers of CP8+ S. aureus; however, baseline anti-CP5 levels were not significantly higher in individuals persistently colonized with CP5+ S. aureus. Statistically significant rises in antibody concentrations were noted after vaccination. At Day 42, 14 of 19 persistent carriers remained colonized; 5 subjects did not have evidence of S. aureus colonization. Ten additional subjects were positive for S. aureus at Day 42 who were not persistently colonized at baseline. Serum antibody concentrations were not statistically different between those with persistent carriage vs. those that lost carriage or those with newly acquired carriage.

Conclusions

Immune responses to vaccine were brisk and comparable in subjects with or without persistent colonization. Despite a substantial rise in anti-CP5 and anti-CP8 antibody concentrations post-vaccination, S. aureus nasal colonization rates did not significantly change.     

Ultraviolet (UV)-reflective paint with ultraviolet germicidal irradiation (UVGI) improves decontamination of nosocomial bacteria on hospital room surfaces

An ultraviolet germicidal irradiation (UVGI) generator (the TORCH, ClorDiSys Solutions, Inc.) was used to compare the disinfection of surface coupons (plastic from a bedrail, stainless steel, and chrome-plated light switch cover) in a hospital room with walls coated with ultraviolet (UV)-reflective paint (Lumacept) or standard paint. Each surface coupon was inoculated with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus faecalis (VRE), placed at 6 different sites within a hospital room coated with UV-reflective paint or standard paint, and treated by 10 min UVC exposure (UVC dose of 0–688 mJ/cm² between sites with standard paint and 0–553 mJ/cm² with UV-reflective paint) in 8 total trials. Aggregated MRSA concentrations on plastic bedrail surface coupons were reduced on average by 3.0 log₁₀ (1.8 log₁₀ Geometric Standard Deviation [GSD]) with standard paint and 4.3 log₁₀ (1.3 log₁₀ GSD) with UV-reflective paint (p = 0.0005) with no significant reduction differences between paints on stainless steel and chrome. Average VRE concentrations were reduced by ≥4.9 log₁₀ (<1.2 log₁₀ GSD) on all surface types with UV-reflective paint and ≤4.1 log₁₀ (<1.7 log₁₀ GSD) with standard paint (p < 0.05). At 5 aggregated sites directly exposed to UVC light, MRSA concentrations on average were reduced by 5.2 log₁₀ (1.4 log₁₀ GSD) with standard paint and 5.1 log₁₀ (1.2 log₁₀ GSD) with UV-reflective paint (p = 0.017) and VRE by 4.4 log₁₀ (1.4 log₁₀ GSD) with standard paint and 5.3 log₁₀ (1.1 log₁₀ GSD) with UV-reflective paint (p < 0.0001). At one indirectly exposed site on the opposite side of the hospital bed from the UVGI generator, MRSA concentrations on average were reduced by 1.3 log₁₀ (1.7 log₁₀ GSD) with standard paint and 4.7 log₁₀ (1.3 log₁₀ GSD) with UV-reflective paint (p < 0.0001) and VRE by 1.2 log₁₀ (1.5 log₁₀ GSD) with standard paint and 4.6 log₁₀ (1.1 log₁₀ GSD) with UV-reflective paint (p < 0.0001). Coating hospital room walls with UV-reflective paint enhanced UVGI disinfection of nosocomial bacteria on various surfaces compared to standard paint, particularly at a surface placement site indirectly exposed to UVC light.     

Effect of UV-C light on anthocyanin content and other quality parameters of pomegranate juice

Pomegranate juice (PJ) was subjected to UV-C irradiation as a non-thermal technology and changes in major quality characteristics of juice such as anthocyanins, polymeric colour, antioxidant activity and total phenol content were determined. The results were compared with control (untreated) and heat treated (at 90 °C, 2 min) juice samples. UV-C treatment preserved the major quality characteristics of pomegranate juice better than heating process. After UV-C treatment, total monomeric anthocyanin content of pomegranate juice did not change significantly and decrease in individual anthocyanin pigments were between 8.1% and 16.3%. However, anthocyanin content of PJ was significantly affected by heat treatment (P < 0.05) and 15.4% and 28.3% of individual anthocyanin pigments were lost after this process. Also, differences between the control and UV-C treated PJ samples were small in terms of polymeric colour values (P > 0.05) while polymeric colour of PJ were significantly affected by heat treatment (P < 0.05). There were no significant changes in antioxidant capacity evaluated by trolox equivalent antioxidant capacity (TEAC) assay and total phenol contents of PJ after UV-C and heat treatments. The effectiveness of the UV-C system on the aerobic plate count, yeast and mould count and Esherichia coli ATCC 25922 as a surrogate microorganism of E. coli O157:H7 in PJ resulted in 1.8, 1.45 and 6.15 log reductions, respectively.     

Methicillin-resistant�CStaphylococcus aureus Hospitalizations, United States

Methicillin-resistant Staphylococcus aureus (MRSA) is increasingly a cause of nosocomial and community-onset infection with unknown national scope and magnitude. We used the National Hospital Discharge Survey to calculate the number of US hospital discharges listing S. aureus–specific diagnoses, defined as those having at least 1 International Classification of Diseases (ICD)-9 code specific for S. aureus infection. The number of hospital discharges listing S. aureus-specific diagnoses was multiplied by the proportion of methicillin resistance for each corresponding infection site to determine the number of MRSA infections. From 1999 to 2000, an estimated 125,969 hospitalizations with a diagnosis of MRSA infection occurred annually, including 31,440 for septicemia, 29,823 for pneumonia, and 64,706 for other infections, accounting for 3.95 per 1,000 hospital discharges. The method used in our analysis may provide a simple way to assess trends of the magnitude of MRSA infection nationally.     

Somatic and reproductive development in pre-pubertal mice treated with cyclophosphamide and subsequent estrogen replacement

We tested the hypothesis that chemotherapy would prevent the expected pubertal development of uterus, ovaries, and long bones, and that estrogen replacement subsequent to treatment with chemotherapy would restore uterine and bone development to expected sizes. Pre-pubertal female C57BL/6J mice (n?=?78) were assigned to receive placebo (controls), 200?mg/kg (group A), or 120?mg/kg (group B) of cyclophosphamide (CTX) on postnatal day 18. Mice were subsequently randomized to receive estradiol placebo or long-release estradiol pellet insertion on day 22 (early estradiol dose), day 45 (mid estradiol dose), or day 67 (late estradiol dose) of life. Body weight and length, uterine and ovarian weight, and right femur length and weight were measured. Mice treated with CTX had shorter and lighter femurs and lighter ovaries than controls (13.46?cm?±?1.51?cm vs. 15.00?cm?±?1.10?cm, 57.70?mg?±?9.71?mg vs. 65.30?mg?±?3.68?mg, and 5.16?mg?±?3.00?mg vs. 10.05?mg?±?2.31?mg, respectively; p?<?0.05). Mice receiving estrogen replacement had a larger average body weight, BMI, and uterine weight than those that received placebo estrogen (19.56?g?±?1.82?g vs. 18.10?g?±?2.08?g, 26.53?g/cm²?±?2.91?g/cm² vs. 23.47?g/cm²?±?3.06?g/cm², 101.19?mg?±?41.69?mg vs. 50.00?mg?±?9.49?mg, respectively; p <?0.05). Cyclophosphamide treatment in pre-pubertal mice negatively affected femur and reproductive development. Estrogen treatment restored expected uterine development by maturity, regardless of the timing of administration. However, there was no similar recovery of femur length and bone mass was only partially recovered.     

An evaluation of personal airborne asbestos exposure measurements during abatement of dry wall and floor tile/mastic

This investigation provides information on exposure to workers during asbestos abatement of dry wall and floor tile/mastic. Personal airborne exposure concentrations were collected during an asbestos abatement project involving dry wall material and floor tile/mastic. Twenty-five dry wall and twenty-three floor tile/ mastic personal air samples were collected during abatement. Exposure concentrations for dry wall and floor tile/mastic abatement were 0.85 f cm^?3-TWA (time-weighted average) and 0.04 f cm^?3-TWA for arithmetic means and 0.72 f cm^?3-TWA and 0.03 f cm^?3-TWA for geometric means, respectively. One outlier was determined for dry wall and none for floor tile/mastic. Sample distribution exhibited variability and was non-normal (logarithmic) for both types of materials abated. Probability of exceeding the Occupational Safety and Health Administration Permissible Exposure Limit for floor tile/mastic was low. Employment of respirators during abatement of floor tile/mastic is not required by regulatory standards, but is necessary for dry wall abatement. Comparison of exposure for within- and between-workers suggests that the process of abatement is the important factor for source of exposure. These exposure data suggest that dry wall abatement workers are not a homogeneous group, but floor tile/mastic workers are a homogeneous group.     

Leaf Composition of American Bur-Reed (<Emphasis Type="Italic">Sparganium americanum</Emphasis> Nutt.) to Determine Pesticide Mitigation Capability

American bur-reed (Sparganium americanum Nutt.), a common aquatic plant in the middle and eastern United States and Canada, is often located in water-retaining drainage areas. The purpose of this study was to determine the leaf composition of S. americanum, paying attention to the cuticular waxes and the epidermis, and its ability to sorb pesticides. S. americanum leaves (n?=?100) were collected in both early (June) and late (August) summer. Transverse sections of S. americanum were stained and studied with brightfield and fluorescence microscopy to estimate the structural and chemical nature of the leaf tissues cross sections. Mean total lipid content in early summer leaf samples (1.47?±?0.83 mg mL^?1) was significantly greater (alpha 0.05) than late summer leaves (0.15?±?0.36 mg mL^?1). In vitro analysis of epidermal peel permeability exposed to atrazine and malathion determined little to no sorption by the plant. Therefore, the structure of S. americanum leaves suggest this species does not have the capacity of sorbing these pesticides from runoff water.