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PubMed2005

Sub-lethal exposure of cockroaches to boric acid pesticide contributes to increased Bla g 2 excretion.

BACKGROUND: Several epidemiology studies have found an increase in the major cockroach allergen Bla g 2 with reported pesticide use. AIMS OF THE STUDY: Our aim was to investigate the effect on the excretion of Bla g 1 and Bla g 2 allergens by cockroaches exposed to sub-lethal doses of the pesticides, boric acid and hydramethylnon gel. METHODS: German cockroaches in separate colonies were fed either boric acid or hydramethylnon gel at concentrations of 0.2, 0.1 and 0.01% in their water supply over a 2 week period. Ten colonies were exposed to each treatment concentration. Bla g 1 and Bla g 2 in fecal pellets were measured by ELISA. RESULTS: Cockroaches exposed to boric acid excreted fecal pellets with significantly higher concentrations of Bla g 2 (35,400 U/g) than did controls (12,700 U/g) (P = 0.001). Bla g 1 concentrations were not significantly different. There was no difference in either Bla g 1 or Bla g 2 concentrations between cockroaches that ingested hydramethylnon gel and those in the controls colonies. CONCLUSIONS: The application of boric acid, a common pesticide, appears to paradoxically increase the production of Bla g 2, a major allergen, by the surviving cockroaches. This may have important implications in avoidance strategies.

Animals↗
PubMed1991

Fluorometric characterization of dityrosine: complex formation with boric acid and borate ion.

Borate/boric acid solutions have distinctive effects on the absorption and fluorescence emission spectra of dityrosine. In the presence of excess borate/boric acid, the fluorescence emission maximum of the singly ionized dityrosine chromophore shifts from 407 nm (quantum yield = 0.80) to 374 nm (quantum yield = 0.14). Fluorescence measurements performed as a function of pH and concentration are consistent with a 1:1 complex which may dissociate to either boric acid and singly ionized dityrosine (K1 = 17 mM) or to monoborate ion and unionized dityrosine (K2 = 0.10 mM). As a consequence of the pKa values characteristic of dityrosine and boric acid, complex formation is maximal near pH 8. 2,2'-Dihydroxy-biphenyl shows similar interactions. The fluorescence of dityrosyl calmodulin (0 Ca2+) also responds to the addition of boric acid, giving K1 = 42 mM and K2 = 2 mM. Singly ionized dityrosine produced through dissociation occurring in the excited state does not interact with boric acid.

Borates↗
PubMed1990

Effect of acute exposure to boric acid on the male reproductive system of the rat.

Adult male rats were dosed orally on d 0 with 0 or 2000 mg/kg of boric acid and killed on posttreatment d 2, 14, 28, and 57, or dosed with 0, 250, 500, 1000, or 2000 mg/kg of boric acid and killed on posttreatment d 14. At d 14, atypical structures that appeared to be enlarged irregular cytoplasmic lobes of Step 19 spermatids were observed in Stage VIII seminiferous tubules of rats dosed with 1000 and 2000 mg/kg. Abnormal retention of Step 19 spermatids and residual bodies was also observed in Stage IX-XIII tubules of these rats. The retained spermatids and residual bodies were seen in both the luminal and basal regions of the epithelium. A substantial increase in the testicular sperm head count occurred in animals dosed with 2000 mg/kg. Abnormal caput epididymal sperm morphology and reduced caput epididymal sperm reserves were observed at 1000 mg/kg and higher. Serum LH, FSH, TSH, and prolactin values were not affected at any dosage. At d 28, rats dosed with 2000 mg/kg exhibited continued retention of Step 19 spermatids into Stage X, abnormal caput and cauda sperm morphology, and decreased percentages of motile cauda spermatozoa with reduced straight-line swimming velocities. By d 57 substantial recovery was apparent; some retention of Step 19 spermatids into Stage X tubules was still present in two out of six rats but the sperm parameters were comparable to controls. The study indicated that acute oral exposure to boric acid adversely affected spermiation and sperm quality in the adult male rat. At the dosages used the effects appeared reversible. The no-effect level was 500 mg/kg.

Administration, Oral↗
PubMed2004

Water solutions of boric acid and sugar for management of German cockroach populations in livestock production systems.

Pest management in confinement swine production relies primarily on calendar-based applications of broad-spectrum insecticides. However, regulatory restrictions imposed by the U.S. Food Quality Protection Act of 1996, the large financial obligation of pesticide registration, and development of insecticide resistance have led to a renewed search for alternative control methods. Boric acid dust has long served as an insecticide in urban pest management and has been shown an effective alternative for use in sensitive environments such as swine production. However, dust formulations are difficult to apply and require specialized equipment. The purpose of this study was to evaluate the efficacy of liquid baits containing boric acid for the control of German cockroaches in a commercial swine nursery. Bait, consisting of 1 or 2% boric acid and 0.5 M sucrose, was deployed in 21 bait delivery tubes per room. Results of a 2-yr study showed significant reductions in cockroach populations. When baits were withdrawn in the summer, the cockroach population increased significantly faster than when the baits were removed during the winter. These data indicate that liquid formulations of boric acid effectively reduce the burden of cockroach infestation in swine production. This approach should have applications in structures in other urban and agricultural environments.

Animals↗
PubMed1982

Absorption of boric acid through human skin depending on the type of vehicle.

Three per cent boric acid incorporated in an anhydrous, water-emulsifying ointment causes no increase of boron levels in blood and urine during a period of 1-9 days after a single topical application. The same amount of boric acid incorporated in a water-based jelly does cause an increase in blood and urine levels, beginning within 2-6 h after application. The decisive factor is the degree of liberation of boron from the vehicle. Skin conditions, such as erythema, eczema, or psoriasis are of minor importance to boron skin permeability, as compared to the characteristics of the vehicle. Blood levels and urine excretion of boron depend on the daily uptake of boron through food.

Administration, Topical↗
PubMed1998

In vitro percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in human skin: a summary.

Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax and disodium octaborate tetrahydrate (DOT) in biological matrices. In vitro human skin percent doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 microg/cm2/h, and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05%, 0.5%, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microL/cm2 volume. At 2 microL/cm2 (the in vivo dosing volume), flux decreased some 200-fold to 0.07 microg/cm2/h and Kp of 1.4 x 10(-6) cm/h, while percent dose absorbed was 1.75%. Borax dosed at 5.0%/1000 microL/cm2 had 0.41 percent dose absorbed, flux at 8.5 microg/cm2/h, and Kp was 1.7 x 10(-4) cm/h. Disodium octaborate tetrahydrate (DOT) dosed at 10%/1000 microL/cm2 was 0.19 percent dose absorbed, flux at 7.9 microg/cm2/h, and Kp was 0.8 x 10(-4) cm/h. These in vitro results from infinite doses (1000 microL/cm2) were a 1000-fold greater than those obtained in the companion in vivo study. The results from the finite (2 microL/cm2) dosing were closer (10-fold difference) to the in vivo results. General application of infinite dose percutaneous absorption values for risk assessment is questioned by these results.

Adult↗
PubMed1997

Treatment of Torulopsis glabrata vaginitis: retrospective review of boric acid therapy.

The charts of all patients who were seen at a vaginitis clinic between January 1989 and December 1994 were retrospectively reviewed; 80 patients whose vaginal cultures yielded Torulopsis glabrata were identified. Sixty of these patients experienced 75 symptomatic episodes of vaginitis attributed to T. glabrata, and these patients are the subject of this review. Of the 60 symptomatic patients, 40 had uncomplicated T. glabrata infection, and 20 had mixed infection, most commonly in association with bacterial vaginosis. Evaluation of treatment of T. glabrata vaginitis with vaginal boric acid (600 mg/d for 14 days) revealed clinical improvement or cure in 21 (81%) of 26 episodes and mycological eradication in 20 (77%) of 26 episodes. One-third of the patients received maintenance therapy with boric acid. The clinical response and mycological eradication rates associated with therapy with topical and systemic azoles were <50%. The rate of therapeutic response to boric acid administered to patients with mixed T. glabrata infection remained high. In conclusion, in this series of patients with T. glabrata vaginitis, for whom repeated courses of antimycotic therapy with azoles had previously failed, boric acid emerged as a promising modality of therapy.

Antifungal Agents↗
PubMedDate not supplied

Experimental exposure of broiler chickens to boric acid to assess clinical signs and lesions of toxicosis.

One-day-old broiler chicks were housed on litter treated with 0, 0.9, 3.6, or 7.2 kg of boric acid per 9.3 m2 of floor space. After 15 days, average body weights were 340.7 g, 278.1 g, and 213.2 g for chickens exposed to 0, 3.6, and 7.2 kg boric acid/9.3 m2, respectively (P < or = 0.05). Feed conversion was 1.68 and 2.29 in chickens exposed to 0 and 7.2 kg boric acid/9.3 m2 (P < or = 0.05). In a second experiment, after birds ingested feed treated with 2500 and 5000 ppm of boric acid for 2 weeks, body weights were 254.8 g and 149.6 g, respectively. The chickens in the control group weighed an average of 285.0 g (P < or = 0.05). The 5000 ppm treatment group had a feed conversion of 1.70, vs. 1.45 in the controls (P < or = 0.05). A dose-related feathering abnormality was evident in treated chickens. No significant histopathologic changes were observed. Livability, weight gain, and feed conversion were not adversely affected in broilers as a result of exposure to litter treated with boric acid at recommended levels of 0.4-0.9 kg/9.3 m2.

Animals↗
PubMed2005

Synergistic effect of EDTA and boric acid on corneal penetration of CS-088.

In order to investigate the effects of EDTA and boric acid (EDTA/boric acid) on the corneal penetration of CS-088, an ophthalmic agent, the apparent permeability coefficient of CS-088 in the presence of EDTA/boric acid across the isolated corneal membranes of rabbits was measured using an in vitro penetration chamber system. FITC-dextran (M.W. 4400) and an electrical method based on membrane resistance were used to provide a quantitative assessment of the enhancing effect of EDTA/boric acid. The corneal penetration of CS-088 was significantly enhanced in the presence of EDTA/boric acid by approximately 1.6-fold. The permeability-enhancing effect of EDTA/boric acid was apparently synergistic and concentration-dependent on both EDTA and boric acid. The penetration of FITC-dextran, a paracellular marker, and electrical resistance of corneal membranes were not affected in the presence of EDTA/boric acid. Furthermore, no enhancing effect of EDTA/boric acid was observed in de-epithelialized corneas, although de-epithelialized corneas exhibited a markedly higher permeability of CS-088 that was 24-fold greater than that for intact corneas. In conclusion, EDTA/boric acid synergistically enhances the transcellular permeability of CS-088 in the outer layer but not in the inner layers of the corneal membrane.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2001

Efficacy of maintenance therapy with topical boric acid in comparison with oral itraconazole in the treatment of recurrent vulvovaginal candidiasis.

OBJECTIVE: Our purpose was to examine the efficacy of a topical long-term treatment with boric acid versus an oral long-term treatment (itraconazole) in the cure and prevention of recurrent vulvovaginal candidiasis. STUDY DESIGN: A prospective, nonrandomized study of patients affected by recurrent vulvovaginal candidiasis was undertaken. In 3 years we recruited 22 consecutive patients who underwent therapy with itraconazole (group 1) or boric acid (group 2). Women were followed up for 1 year, with clinic and microbiologic controls after 1, 3, 6, and 12 months after the first visit. RESULTS: During the treatment, the positive culture results (15.1% vs 12.1%) and the signs and symptoms (33.3% vs. 24.2%) were similar within the 2 groups, with no significant statistical difference. With the withdrawal, after 6 months relapses were common in the 2 groups (54.5%). CONCLUSIONS: Boric acid seems to be a valid and promising therapy both in the cure of the vaginal infection and in the prevention of relapses of recurrent vulvovaginal candidiasis, but its efficacy ends with the suspension of the therapy.

Adult↗
PubMed1984

Colorimetric method for the determination of ketoses using phenol-acetone-boric acid reagent (PABR).

A purplish pink color developed when ketose solution (100 microliters) was mixed with phenol-acetone-boric acid reagent (0.5 ml 5% phenol, 2% acetone, 4% boric acid) and then treated with 96% sulfuric acid (1.4 ml). The absorbance of the reaction mixture was measured at 568 nm after 60 min at 37 degrees C. This method allowed the simple determination of 3-50 nmol of D-fructose with coefficient of variation 7.8% for 3 nmol and 2.8% for 50 nmol. Carbohydrates other then ketoses did not interfere with this reaction. The influence of various chemicals on the colorimetric reaction and applicability of the method for determination of ketoses in natural products are presented.

Acetone↗
PubMed1984

Boric acid single dose pharmacokinetics after intravenous administration to man.

Eight young adult male volunteers with a basic (alimentary) plasma boric acid concentration of less than 0.10 - 0.46 mg/l were given a single dose of boric acid (562-611 mg) by 20 min IV infusion. The plasma concentration curves, followed for 3 days, best fitted a three-compartment open model, although two subjects had to be left out due to inconstant basal plasma concentration values or failure to fit to the three-compartment model. The 120 h urinary excretion was 98.7 +/- 9.1% of dose, Cltot 54.6 +/- 8.0 ml/min/1.73 m2, t1/2 beta 21.0 +/- 4.9 h and distribution volumes V1, V2, and V3: 0.251 +/- 0.099, 0.456 +/- 0.067 and 0.340 +/- 0.128 l/kg.

Adult↗
PubMedDate not supplied

Periods of vertebral column sensitivity to boric acid treatment in CD-1 mice in utero.

Boric acid (BA) has many uses as an industrial compound and is widely distributed in the environment. BA has been shown to produce rib agenesis, a rare effect in laboratory animals. This study was conducted to determine if there is a period of sensitivity to this unusual effect. BA (500 or 750 mg/kg) was administered p.o. to pregnant CD-1 mice once daily on gestational days (GDs) 6-10. A reduction of 13th rib length occurred at both dose levels. BA 400mg/kg was also administered twice daily on GD 6, 7, 8, 9, or 10 or on GDs 6-8. A significant decrease in average fetal weight was observed in all treatment groups. Significant increases in the incidence of cervical ribs/ossifications resulted from treatments on GD 7 and GDs 6-8. Rib agenesis occurred with treatment on GD 8 and GDs 6-8. Reduced rib length, a decreased incidence of supernumerary ribs (SNR), and an increased incidence of fused and/or branched ribs occurred when dams were treated GDs 6-8. Doses of 750 mg/kg given twice on day 8 produced significant increases in several thoracic skeletal anomalies. Further studies of pathogenesis are necessary to determine the earliest perturbations and the processes that are affected. The sensitivity of embryos to treatment on GD 8 to rib agenesis suggests that BA is affecting early processes such as gastrulation and presomitic mesoderm formation and patterning in this area.

Abnormalities, Drug-Induced↗
PubMed2005

Boric acid as a mobile phase additive for high performance liquid chromatography separation of ribose, arabinose and ribulose.

A new high performance liquid chromatographic (HPLC) method is described for the analysis of ribose, arabinose and ribulose mixtures obtained from (bio)chemical isomerization processes. These processes gain importance since the molecules can be used for the synthesis of antiviral therapeutics. The HPLC method uses boric acid as a mobile phase additive to enhance the separation on an Aminex HPX-87K column. By complexing with boric acid, the carbohydrates become negatively charged, thus elute faster from the column by means of ion exlusion and are separated because the complexation capacity with boric acid differs from one carbohydrate to another. Excellent separation between ribose, ribulose and arabinose was achieved with concentrations between 0.1 and 10 gL(-1) of discrete sugar.

Aldose-Ketose Isomerases↗
PubMed1998

A comparative review of the pharmacokinetics of boric acid in rodents and humans.

The pharmacokinetics of boric acid (BA) have been studied in animals and humans. Orally administered BA is readily and completely absorbed in rats, rabbits, and humans, as well as other animal species. In animals and humans, absorbed BA appears to be rapidly distributed throughout the body water via passive diffusion. Following administration of BA, the ratio of blood: soft tissue concentrations of boron (B) is approx 1.0 in rats and humans; in contrast, concentrations of B in bone exceed those in blood by a factor of approx 4 in both rats and humans. In rats, adipose tissue concentrations of B are only 20% of the levels found in blood and soft tissues; however, human data on adipose tissue levels are not available. BA does not appear to be metabolized in either animals or humans owing to the excessive energy required to break the B-O bond. BA has an affinity for cis-hydroxy groups, and it has been hypothesized to elicit its biological activity through this mechanism. The elimination kinetics of BA also appear to be similar for rodents and humans. BA is eliminated unchanged in the urine. The kinetics of elimination were evaluated in human volunteers given BA orally or intravenously; the half-life for elimination was essentially the same (approx 21 h) by either route of exposure. In rats, blood and tissue levels of B reached steady-state after 3-4 d of oral administration of BA; assuming first-order kinetics, a half-life of 14-19 h may be calculated. The lack of metabolism of BA eliminates metabolic clearance as a potential source of interspecies variation. Accordingly, in the absence of differences in metabolic clearance, renal clearance is expected to be the major determinant of interspecies variation in pharmacokinetics. Because glomerular filtration rates are slightly higher in rats than in humans, the slight difference in half-lives may be readily explained. The most sensitive toxicity end point for BA appears to be developmental toxicity in rats, with a No Observed Adverse Effect Level (NOAEL) and Lowest Observed Adverse Effect Level (LOAEL) of 55 and 76 mg BA/kg/d, respectively. Mean blood B levels in pregnant rats on gestation day 20 in the pivotal developmental toxicity study were reported to be 1.27 and 1.53 mcg B/g at the NOAEL and LOAEL, respectively. Blood B concentrations in humans are well below these levels. Average blood B levels in the most heavily exposed worker population at a borate mine was 0.24 mcg B/mL, and the estimated daily occupational exposure was equivalent to 160 mg BA/d. Blood B levels in the general population generally range from 0.03 to 0.09 mcg B/mL. These blood B values indicate an ample margin of safety for humans. In summary, the pharmacokinetics of BA in humans and rodents are remarkably similar, and interspecies differences in pharmacokinetics appear to be minimal.

Absorption↗
PubMed2006

Effects of subacute boric acid administration on rat kidney tissue.

BACKGROUND/AIMS: Boron is used in manufacturing processes and numerous consumer products. Clarification of boron toxicity is important because of industrial and consumer exposure to boron and boron-containing compounds. The aim of this study was to observe effects of subacute boric acid administration on rat kidney tissue. MATERIALS AND METHODS: A total of 96 male albino Sprague-Dawley rats were used in this study. Seventy-two rats were selected for the experimental group and 24 rats constituted the control group. Experimental group rats were divided into three groups for exposure to three different doses of orally administered boric acid (100-275-400 mg/kg/day). Kidney tissues were removed at the 10th, 30th, and 45th day after sacrificing the rats. Kidney weights, kidney boron concentration and histopathological changes were determined. RESULTS: In the experimental group, a significant accumulation of boron in kidney tissue was seen, but there was a significant drop in boron concentration on the 45th day compared with the 30th day. Histopathological degenerative changes were observed especially in the proximal tubule cells that were dose- and time-dependent. CONCLUSION: Subacute boric acid exposure caused dose-dependent histopathological changes in kidney tissue.

Administration, Oral↗
PubMed1988

Proteus mirabilis urease. Partial purification and inhibition by boric acid and boronic acids.

Urease was purified 800-fold and partially characterized from Proteus mirabilis, the predominant microorganism associated with urinary stones. Boric acid is a rapid reversible competitive inhibitor of urease. The pH-dependence of inhibition exhibited pKa values of 6.25 and 9.3, where the latter value is probably due to the inherent pKa of boric acid. Three boronic acids also were shown to inhibit urease competitively.

Boric Acids↗