Is Boric Acid Toxic to Reproduction in Humans? Assessment of the Animal Reproductive Toxicity Data and Epidemiological Study Results.

Boric acid and sodium borates are classified as toxic to reproduction in the CLP Regulation under "Category 1B" with the hazard statement of "H360FD". This classification is based on the reprotoxic effects of boric acid and sodium borates in animal experiments at high doses. However, boron mediated reprotoxic effects have not been proven in epidemiological studies so far. The epidemiological study performed in Bandirma boric acid production plant is the most comprehensive published study in this field with 204 voluntarily participated male workers. Sperm quality parameters (sperm morphology, concentration and motility parameters), FSH, LH and testosterone levels were determined in all participated employees as the reproductive toxicity biomarkers of males. However, boron mediated unfavorable effects on reproduction in male workers have not been determined even in the workers under very high daily boron exposure (0.21 mg B/kg-bw/day) conditions. The NOAEL for rat reproductive toxicity is equivalent to a blood boron level of 2020 ng/g. This level is higher than the mean blood boron concentration (223.89 ± 69.49 ng/g) of the high exposure group workers in Bandirma boric acid production plant (Turkey) by a factor of 9. Accordingly, classifying boric acid and sodium borates under "Category 1B" as "presumed reproductive human toxicant in the CLP regulation seems scientifically not reasonable. The results of the epidemiological studies (including the study performed in China) support for a down-classification of boric acid from the category 1B, H360FD to category 2, H361d, (suspected of damaging the unborn child).

Assessment of immunotoxicity and genotoxicity in workers exposed to low concentrations of formaldehyde.

Formaldehyde (FA), which is an important chemical with a wide commercial use, has been classified as carcinogenic to humans by International Research on Cancer (IARC). The genotoxic and carcinogenic potential of FA has been documented in mammalian cells and in rodents. A recent evaluation by the E.U. Scientific Committee for Occupational Exposure Limits (SCOEL) anticipated that an 8-h time-weighted average exposure to 0.2 ppm FA would not be irritating and not genotoxic in humans. In order to verify this prediction, a field study was performed that aimed at evaluating immune alterations and genetic damage in peripheral lymphocytes of workers in medium density fiberboard plants exposed to a level of FA equivalent to the OEL recommended by SCOEL (0.2 ppm). Subsets of peripheral lymphocytes, immunoglobulins (IgG, IgA, IgM), complement proteins, and tumor necrosis factor-alpha (TNF-α) levels were evaluated. DNA damage of the workers was assessed by the Comet assay. The absolute numbers and the percentages of T lymphocytes and of natural killer cells, and the levels of TNF-α were higher than the controls, whereas IgG and IgM levels were found to be lower in workers. Other examined immunological parameters were not different from those of the controls. There was no increased DNA damage in the workers compared to controls.

Assessment of DNA integrity (COMET assay) in sperm cells of boron-exposed workers.

An extension of a male reproductive study conducted in a boric acid/borate production zone at Bandirma, Turkey, is presented. The relation between DNA-strand breaks (COMET assay, neutral and alkaline version) in sperm cells and previously described sperm quality parameters was investigated in boron-exposed males. A correlation between blood boron levels and mean DNA-strand breaks in sperm was weak, and DNA-strand breaks in sperm were statistically not different between control and exposed groups. Therefore, increasing boron exposures had no additional contribution in addition to already pre-existing DNA-strand breaks in the sperm cells. Weak but statistically significant correlations between DNA-strand breaks and motility/morphology parameters of sperm samples were observed in the neutral version of the COMET assay, while correlations between the same variables were statistically not significant in the alkaline version. A likely reason for these negative results, even in highly exposed humans, is that experimental exposures that had led to reproductive toxicity in animals were significantly higher than any boron exposures, which may be reached under realistic human conditions.

Reproductive toxicity parameters and biological monitoring in occupationally and environmentally boron-exposed persons in Bandirma, Turkey.

Boric acid and sodium borates have been considered as being "toxic to reproduction and development", following results of animal studies with high doses. Experimentally, a NOAEL (no observed adverse effect level) of 17.5 mg B/kg-bw/day has been identified for the (male) reproductive effects of boron in a multigeneration study of rats, and a NOAEL for the developmental effects in rats was identified at 9.6 mg B/kg-bw/day. These values are being taken as the basis of current EU safety assessments. The present study was conducted to investigate the reproductive effects of boron exposure in workers employed in boric acid production plant in Bandirma, Turkey. In order to characterize the external and internal boron exposures, boron was determined in biological samples (blood, urine, semen), in workplace air, in food, and in water sources. Unfavorable effects of boron exposure on the reproductive toxicity indicators (concentration, motility, morphology of the sperm cells and blood levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and total testosterone) were not observed. The mean calculated daily boron exposure (DBE) of the highly exposed group was 14.45 ± 6.57 (3.32-35.62) mg/day. These human exposures represent worst-case exposure conditions to boric acid/borates in Turkey. These exposure levels are considerably lower than exposures, which have previously led to reproductive effects in experimental animals. In conclusion, this means that dose levels of boron associated with developmental and reproductive toxic effects in animals are by far not reachable for humans under conditions of normal handling and use.

The modulating effects of quercetin and rutin on the mitomycin C induced DNA damage.

The present study was carried out to investigate the modulating effects of the two flavonoids quercetin and rutin on the mutagenic anticancer drug mitomycin C by single cell gel electrophoresis (Comet assay) in human lymphocytes. Lymphocytes were incubated with different concentrations of quercetin and rutin, with or without mitomycin C, and DNA damage was evaluated. Concentrations of 0.03, 0.15, 0.3, 0.6, 1.5 and 3mM quercetin significantly reduced the DNA strand breakage induced by mitomycin C (P<0.001) but the highest concentration of 6mM quercetin did not show a protective effect. The frequency of damaged cells induced by mitomycin C was not changed at 0.02 mM, and also at the highest concentrations of 1.64 and 3.28 mM rutin. However, at concentrations of 0.08, 0.16, 0.33 and 0.82 mM rutin cells were protected from DNA damage. Thus, in human lymphocytes quercetin and rutin displayed protective effects on DNA damage induced by mitomycin C, in a concentration-dependent manner.

Effects of ionizing radiation on brain tissue surrounding arteriovenous malformations: an experimental study in a rat caroticojugular fistula model.

Arteriovenous malformation (AVM) may change the cerebral hemodynamics. The purpose of this study was to detect the effects of ionizing radiation (IR) on tissues surrounding AVM in a rat caroticojugular fistula model. Forty rats were divided into four groups. Eight weeks after caroticojugular fistulas and chronic hypoperfusion were created in groups 1 and 2, IR was administered to groups 1 and 3. Group 4 was the control. Brain tissue samples were taken 72 h after irradiation. Comet assay to detect DNA strand breaks (DSB), terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay for apoptosis, and free radical measurement were performed. Although the difference between fistula plus irradiation (group 1) and fistula (group 2) was statistically insignificant in terms of DSB and free radical measurement, apoptotic cell count was significantly higher in group 1. Nonetheless, apoptotic cell count corresponded well with both free radicals and DSB in the irradiated group (group 3). Ionizing radiation resulted in significant apoptosis in both groups with or without fistulas. Chronic hypoperfusion might not prevent cerebral damage after IR. Optimal care should be taken with brain tissue around AVM during radiotherapy, regardless of presence or absence of the "steal" phenomenon.

Monitoring of DNA damage in foundry and pottery workers exposed to silica by the alkaline comet assay.

BACKGROUND: Workers in foundry and pottery are exposed to a mixture of chemicals and silica, which is suspected to cause genetic alterations. METHODS: To investigate the potential hazard associated with the occupational exposure to silica, DNA damage in the peripheral lymphocytes of 30 foundry and 22 pottery workers were examined by the alkaline single-cell gel electrophoresis or Comet Assay, and compared to 52 healthy subjects with no history of occupational silica or chemical exposure. RESULTS: The DNA damage observed in the lymphocytes of both foundry and pottery workers was significantly higher than that in their controls. Cigarette smoking was also related to DNA damage since the DNA damage observed in smoking silica-exposed workers compared with the non-smoking workers was significantly higher. CONCLUSIONS: Occupational exposure of silica from foundry and pottery workplaces has been associated with the increased DNA damage and smoking which represents an additional risk factor and must be avoided.

In vitro immunomodulatory activity of flavonoid glycosides from Urtica dioica L.

The major compounds isolated from the methanolic extract of the aerial parts of Urtica dioica L. were determined as quercetin-3-O-rutinoside (1). kaempherol-3-O-rutinoside (2). and isorhamnetin-3-O-glucoside (3). by chromatographic, chemical (acidic hydrolysis) and spectral (UV, IR, (1)H-NMR, (13)C-NMR) methods. Their immunomodulatory activities were studied in vitro by chemotaxis (Boyden Migration Chamber) and intracellular killing activity (NBT reduction) tests. Compounds 1, 2, 3 and the total flavonoid fraction were determined to have significant chemotactic effects in 4, 8, 16 microg doses. According to the results of the NBT reduction test, all flavonoid glycosides showed high intracellular killing activity. The results of both assays confirmed the immunostimulatory activity of the flavonoid fraction and the isolated flavonoid glycosides on neutrophils suggesting that they could possibly be useful for treating patients suffering from neutrophil function deficiency and chronic granulomatous diseases.

Assessment of DNA strand breakage by the alkaline COMET assay in dialysis patients and the role of Vitamin E supplementation.

Although the role of reactive oxygen species (ROS) in chronic renal failure (CRF) is not definitely demonstrated, a consistent number of observations has provided evidence for the presence of oxidative stress in uremic patients undergoing maintenance dialysis. In order to investigate this hypothesis further and to understand the role of antioxidant supplementation, peripheral blood lymphocytes were taken from 36 dialysis patients before and after Vitamin E supplementation in a dosage of 600 mg per day (2x300 mg) for 14 weeks and examined in the alkaline Comet assay for DNA strand breakage. The results were also compared with those of 36 controls with comparable age, sex, and smoking habits, and with no history of renal disease. The DNA breakage observed in the lymphocytes of patients before Vitamin E supplementation was significantly higher than in the controls (P<0.001) but a clear protective effect of Vitamin E supplementation were observed after 14 weeks of therapy.

In vitro immunomodulatory activity of verbascoside from Nepeta ucrainica L.

Nepeta ucrainica L. is used as a herbal tea in Kazakhistan. Phytochemical investigations of the aerial parts of the plant resulted in the isolation of verbascoside (1) and 1,5,9-epi-deoxyloganic acid (2). The structures of the compounds were elucidated by spectral (UV, IR, (1)H-NMR and (13)C-NMR) methods and HPLC analysis. The in vitro immunomodulatory activity of verbascoside was investigated by assessing neutrophil function; chemotaxis and intracellular killing activity. Verbascoside showed an increased chemotactic activity in all doses applied compared with the medium used as a negative control and had a positive effect on respiratory burst of neutrophils, but there was an opposite effect with increasing doses, pointing to a possible suppression of neutrophil intracellular killing activity.

Alterations in immune parameters in foundry and pottery workers.

To assess the immune competence of workers occupationally exposed to mainly silica, peripheral blood lymphocytes, serum immunoglobulins (IgG, IgA and IgM), C3 and C4 complement protein concentrations of foundry and pottery workers were evaluated and compared to healthy controls with no history of silica and other chemical exposure. The absolute number and percentage of functionally different subsets of peripheral blood mononuclear lymphocytes, i.e. T, T-suppressor and natural killer cells were unchanged. However, T-helper lymphocytes in pottery (P<0.05) and B cells in foundry (P<0.01) workers were significantly lower when compared to their controls. In addition, silica-exposed foundry workers had a significant reduction in the IgG, IgA and IgM levels. No significant differences were observed in the serum complement C3 and C4 levels of the workers. These results suggest that human chronic exposure to mainly silica and other chemicals originating from foundry and pottery settings may be detrimental to the immune system.

Assessment of DNA damage in workers occupationally exposed to pesticide mixtures by the alkaline comet assay.

The potential genetic hazard of pesticides to human beings is of great concern in occupational and environmental settings because of the widespread use of these chemicals for domestic and industrial applications. Various studies have revealed a significantly elevated risk for particular tumours in humans exposed to some pesticides. Results from the biological monitoring or cytogenetic methods for the detection of health risks to pesticides have given both positive and negative results of mutagenicity. In this study DNA damage in peripheral lymphocytes of 33 pesticide-exposed workers employed in the municipality of Ankara (Turkey) for at least 1 year was examined by alkaline single-cell gel electrophoresis, the 'comet' technique. Results were compared with those from 33 controls of comparable age, sex and smoking habits, which were not occupationally exposed to pesticides. Work characteristics of the exposed workers and the use of personnel protective measures were also investigated. The DNA damage observed in lymphocytes of the workers was significantly higher than that in the controls ( P<0.001). The observed DNA damage was found to be significantly lower ( P<0.001) in workers applying some of the necessary individual safety protections during their work. Cigarette smoking was not related to increases in DNA damage; also, no significant association was found between the duration of occupational exposure to pesticides and the degree of DNA damage.

Immunotoxicological investigation in rats dosed repeatedly with combinations of cypermethrin, As(III), and Hg(II).

The effects of the combined exposure of cypermethrin (CY), NaAsO2 (As), and HgCl2 (Hg) were investigated in male Wistar rats following 4 weeks of oral exposure. Standard toxicological (body weight gain, organ weights of brain, thymus, heart, lung, liver, kidneys, adrenals, testes, and popliteal lymph node), haematological (white blood cell, red blood cell, haematocrit, MCV-mean volume of red blood cells, and cell content of the femoral bone marrow), and immune function (IgM-PFC response, delayed type hypersensitivity (DTH) reaction) parameters were measured. The two doses selected for the combination were: a high (H) dose equal to lowest observed effect level determined in preliminary experiments (CY(H)=55.4 mg/kg, As(H)=13.3 mg/kg, Hg(H)=3.20 mg/kg), and a low (L) dose which was ineffective (non-observed effect level); CY(L)=11.1 mg/kg, As(L)=3.33 mg/kg, Hg(L)=0.40 mg/kg). CY(H) was combined with As(L) or Hg(L), and the H doses of the heavy metals were combined with CY(L). Beside vehicle control, the H dose components of the combinations were also used as internal controls. The main finding of this study was that certain combinations, when compared to H dose internal control, significantly altered the body weight gain (As(H)+CY(L)), the relative weight of adrenals and popliteal lymph node (CY(H)+As(L) and CY(H)+Hg(L)), the cell content of the femoral bone marrow (CY(H)+Hg(L)), and the time course of DTH reaction (CY(H)+As(L)). According to the present results, combined exposure with CY and the heavy metals investigated can modify the toxicity and/or the functional detection limit of the single substances.