Cumene Contamination in Groundwater: Observed Concentrations, Evaluation of Remediation by Sulfate Enhanced Bioremediation (SEB), and Public Health Issues.

Isopropylbenzene (cumene) is commonly encountered in groundwater at petroleum release sites due to its natural occurrence in crude oil and historical use as a fuel additive. The cumene concentrations detected at these sites often exceed regulatory guidelines or standards for states with stringent groundwater regulations. Recent laboratory analytical data collected at historical petroleum underground storage tank (UST) release sites have revealed that cumene persists at concentrations exceeding the default cleanup criterion, while other common petroleum constituents are below detection limits or low enough to allow natural attenuation as a remediation strategy. This effectively makes cumene the driver for active remediation at some sites. An insignificant amount of research has been conducted for the in-situ remediation of cumene. Sulfate Enhanced Biodegradation (SEB) is evaluated in a field case study. The results from the field case study show an approximate 92% decrease in plume area following three rounds of SEB injections. An additional objective of this research was to determine the cumene concentration in fuels currently being used to determine future impacts. A review of safety data sheets from several fuel suppliers revealed that cumene concentrations in gasoline are reported typically as wide ranges due to the proprietary formulations. Several fuels from different suppliers were analyzed to determine a baseline of cumene concentration in modern fuels. The results of the analysis indicated that cumene accounts for approximately 0.01% (diesel) to 0.13% (premium gasoline) of the overall fuel composition. Cumene generally is considered to be of low human health toxicity, with the principal concern being eye, skin, and respiratory irritation following inhalation of vapors in an occupational setting, but it has been regulated in Florida at very low concentrations based on organoleptic considerations.

Prevalence of lid wiper epitheliopathy in subjects with dry eye signs and symptoms.

PURPOSE: The purpose of this study was to investigate the prevalence of lid wiper epitheliopathy (LWE) in patients diagnosed with dry eye disease (DED). METHODS: Patients were recruited for two groups. Inclusion criteria for the DED group (n = 50) was: a score greater than 10 with the Standard Patient Evaluation of Eye Dryness questionnaire, fluorescein break-up time 5 seconds or less, corneal and conjunctival staining with fluorescein, lissamine green Grade 1 or greater (scale 0-3), and Schirmer test with anesthesia 5 mm or less. For the asymptomatic group (n = 50), inclusion criteria were: no dry eye symptoms, fluorescein break-up time 10 seconds or greater, no corneal or conjunctival staining, and Schirmer test 10 mm or greater. Sequential instillations (n = 2, 5 minutes apart) of a mixture of 2% fluorescein and 1% lissamine green solution were used to stain the lid wipers of all patients. LWE was graded (scale 0-3) using the horizontal lid length and the average sagittal lid widths of the stained wiper. RESULTS: In symptomatic patients, 88% had LWE, of which 22% was Grade 1, 46% Grade 2, and 20% Grade 3. In asymptomatic patients, 16% had LWE, of which 14% was Grade 1, 2% was Grade 2, and 0% Grade 3. The difference in prevalence of lid wiper staining between groups was significant (P < 0.0001). CONCLUSIONS: The prevalence of LWE was six times greater for the DED group and the prevalence of LWE Grade 2 or greater was 16 times greater for the DED group than for the control group. These data further establish LWE as a diagnostic sign of dry eye disease.

An evaluation of the efficacy of fluorescein, rose bengal, lissamine green, and a new dye mixture for ocular surface staining.

PURPOSE: Sodium fluorescein is considered the premier dye for corneal staining and, similarly, rose bengal (RB) for conjunctival staining. A mixture of 1% fluorescein and 1% rose bengal has been reported as advantageous in daily practice. Mixtures of lissamine green with other ocular stains have not been reported. The purposes of this study were to review the clinical staining characteristics of fluorescein, rose bengal, and lissamine green in controlled dose and concentration and determine whether optimal staining of the cornea and bulbar conjunctiva are possible by using dye mixtures. METHODS: Sixteen 10-microL solutions of fluorescein, rose bengal, lissamine green, and their mixtures were evaluated. Fourteen subjects with a diagnosis of dry eye were tested for staining with various combinations of the dyes. Examination of staining was made by using standard clinical practices. RESULTS: A mixture of 2% fluorescein and 1% rose bengal was the most efficacious staining mixture for the cornea and conjunctiva, but moderate to marked discomfort was reported. The mixture of 2% fluorescein and 1% lissamine green did not result in discomfort and provided optimal corneal and conjunctival staining with only slightly less efficacy than 2% fluorescein and 1% rose bengal; 2% and 3% lissamine green produced burning and discomfort. The fluorescent characteristics of fluorescein were not significantly altered by the addition of 1% lissamine green. The preferred mixture for simultaneous and efficacious staining of the cornea and conjunctiva without an adverse sensation was 2% fluorescein and 1% lissamine green. CONCLUSIONS: A mixture of 2% fluorescein and 1% lissamine green offers excellent simultaneous corneal and bulbar conjunctival staining and could replace the use of individual dyes for ocular staining and contact lens practice.

Warm compress induced visual degradation and Fischer-Schweitzer polygonal reflex.

PURPOSE: To document adverse visual effects of warm compress therapy and determine potential etiologies in subjects with dry eye symptoms. METHODS: Subjects (n = 24) with dry eye symptoms were recruited. Group 1 (n = 13): baseline measurements for each eye included subjective blur, visual acuity (VA), autorefraction (AR), corneal topography (CT), central corneal curvature (CCC), lipid layer thickness (LLT), and evaluation for corneal striae and edema. A warm, moist compress (44.4-45 degrees C) was applied with gentle pressure for 30 min to the closed eyelids of the randomized experimental eye; nothing was applied to the contralateral control eye. Subjective blur, VA, AR, CT, CCC, and LLT were evaluated for each eye at 5, 15, and 30 min and 5 min after application. Striae and edema were assessed for each eye at 30 and 5 min after application. Group 2 (n = 11): the above warm compress protocol was repeated to investigate the Fischer-Schweitzer polygonal reflex at the times stated. RESULTS: At 5 and 30 min, 71% and 88% of all subjects experienced increased subjective blur and decreased VA. At 30 min: Group 1: Of 13 experimental eyes: 13 experienced subjective blur; nine exhibited a VA decrease > or =2 lines (mean = 3.4 +/- 0.7). For the control eye, two subjects reported blur and none exhibited decreased VA. The findings for AR, CT, CCC, LLT, striae and edema did not correlate with blur or with VA decline. Group 2: Of 11 experimental eyes: 10 exhibited the polygonal reflex compared with 0 controls (p < 0.001); eight exhibited subjective blur; seven exhibited VA decrease > or =2 lines (mean = 2.9 +/- 0.9). The polygonal reflex correlated positively to visual blur (r = 0.88, p = 0.04) and to VA decrease (r = 0.79, p = 0.1). CONCLUSIONS: Warm compress application induces transient visual degradation. Although there was no correlation between visual degradation and AR, CT, CCC, LLT, or the presence of striae or corneal edema, visual degradation correlated positively with the polygonal reflex, which was observed following warm compress application.

The effect of two novel lubricant eye drops on tear film lipid layer thickness in subjects with dry eye symptoms.

PURPOSE: Because the lipid layer of the tear film is recognized as a critical component in dry eye disease, this study was designed to determine if a single eye drop of either Soothe or Systane produces a significant increase in lipid layer thickness (LLT) for subjects reporting symptoms indicative of dry eyes. METHODS: A double-blind, internally paired study was performed. A custom-built lipid layer interferometer, enabling characterization of lipid layer interference patterns, was used to quantify baseline LLT (OU) of eligible subjects. Inclusion criteria included: 1) presence of dry eye symptoms and 2) baseline LLT < or =75 nm. Subjects (n = 40) received a single eye drop of Soothe in one eye and a single eye drop of Systane in the contralateral eye. After the instillation of each test drop, LLT was reanalyzed for all subjects. RESULTS: The mean +/- standard error baseline LLT pre-eye drop instillation was 60.0 +/- 1.8 nm for eyes treated with Soothe and 61.5 +/- 1.8 nm for eyes treated with Systane. These means were not significantly different (p > 0.5). The mean LLT for eyes treated with Soothe increased to 124.4 +/- 4.9 nm (p < 0.0001). The mean LLT for eyes treated with Systane increased to 71.3 +/- 2.6 nm (p < 0.0001). The LLT increase from Soothe was significantly greater than that from Systane (p < 0.0001). CONCLUSIONS: In subjects with symptoms indicative of dry eye states and LLT < or =75 nm, one eye drop of Soothe more than doubled LLT, a 107% mean increase, whereas Systane increased LLT by 16%.

Lid wiper epitheliopathy and dry eye symptoms.

OBJECTIVES: The lid wiper is defined as that portion of the marginal conjunctiva of the upper eyelid that wipes the ocular surface during blinking. The purpose of this study was to investigate whether lid wiper epitheliopathy occurred with patients who reported dry eye symptoms, yet had normal fluorescein breakup time (FBUT) and Schirmer test values and an absence of fluorescein corneal staining. METHODS: One hundred patients were divided into two groups based on the presence or absence of dry eye symptoms, as determined with the Standard Patient Evaluation of Eye Dryness questionnaire. Other criteria for admission to both groups were FBUT of 10 seconds or more, Schirmer test value of 10 mm or more, and absence of fluorescein corneal staining. After instillation of fluorescein and rose bengal dyes, the lid wipers of 50 asymptomatic and 50 symptomatic patients were graded for staining from grade 0 (absent) to grade 3 (severe). RESULTS: Of the symptomatic patients, 76% had staining of the lid wiper: 44%, grade 1; 22%, grade 2; and 10%, grade 3. Of the asymptomatic patients, 12% had staining; 8%, grade 1; 4%, grade 2; and 0%, grade 3. The difference in prevalence of lid wiper staining between the symptomatic and asymptomatic groups was significant (P<0.0001). CONCLUSIONS: Lid wiper epitheliopathy, diagnosed by staining with fluorescein and rose bengal dyes, is a frequent finding when symptoms of dry eye are experienced in the absence of routine clinical dry eye findings.

Lid-wiper epitheliopathy and dry-eye symptoms in contact lens wearers.

PURPOSE: To evaluate whether dry-eye symptoms are associated with epitheliopathy of that portion of the upper eyelid marginal conjunctiva-the lid wiper-that wipes the ocular, or contact lens surface, during blinking. METHODS: Subjects were divided into two groups based on the presence or absence of dry-eye symptoms. The lid wiper of asymptomatic (n=75) and symptomatic (n=30) soft contact lens wearers was examined, following the instillation of fluorescein and rose bengal dyes. Lid-wiper staining was graded zero to 3. RESULTS: Eighty percent of the symptomatic subjects displayed lid-wiper staining compared to 13% of the asymptomatic subjects. The difference in staining between the two groups was significant (P<0.0001). Of the symptomatic subjects, 20% showed no staining; 26.6%, grade 1 staining; 36.6%, grade 2; and 16.6% showed grade 3 staining. Of the asymptomatic subjects, 87% exhibited no staining; 9%, grade 1 staining; 3%, grade 2; and 1% showed grade 3 staining. CONCLUSIONS: This study describes a new clinical condition, lid-wiper epitheliopathy, an alteration of the epithelium of that portion of the marginal conjunctiva of the upper eyelid that wipes the ocular surface, diagnosed by staining with fluorescein and rose bengal dyes.