Boron Intake Research Articles

Activation of the EIF2\u03b1/ATF4 and ATF6 Pathways in DU-145 Cells by Boric Acid at the Concentration Reported in Men at the US Mean Boron Intake

Fruits, nuts, legumes, and vegetables are rich sources of boron (B), an essential plant nutrient with chemopreventive properties. Blood boric acid (BA) levels reflect recent B intake, and men at the US mean intake have a reported non-fasting level of 10 μM. Treatment of DU-145 prostate cancer cells with physiological concentrations of BA inhibits cell proliferation without causing apoptosis and activates eukaryotic initiation factor 2 (eIF2α). EIF2α induces cell differentiation and protects cells by redirecting gene expression to manage endoplasmic reticulum stress. Our objective was to determine the temporal expression of endoplasmic reticulum (ER) stress-activated genes in DU-145 prostate cells treated with 10 μM BA. Immunoblots showed post-treatment increases in eIF2α protein at 30 min and ATF4 and ATF6 proteins at 1 h and 30 min, respectively. The increase in ATF4 was accompanied by an increase in the expression of its downstream genes growth arrest and DNA damage-induced protein 34 (GADD34) and homocysteine-induced ER protein (Herp), but a decrease in GADD153/CCAAT/enhancer-binding protein homologous protein (CHOP), a pro-apoptotic gene. The increase in ATF6 was accompanied by an increase in expression of its downstream genes GRP78/BiP, calreticulin, Grp94, and EDEM. BA did not activate IRE1 or induce cleavage of XBP1 mRNA, a target of IRE1. Low boron status has been associated with increased cancer risk, low bone mineralization, and retinal degeneration. ATF4 and BiP/GRP78 function in osteogenesis and bone remodeling, calreticulin is required for tumor suppressor p53 function and mineralization of teeth, and BiP/GRP78 and EDEM prevent the aggregation of misfolded opsins which leads to retinal degeneration. The identification of BA-activated genes that regulate its phenotypic effects provides a molecular underpinning for boron nutrition and biology.

Biological effects of tolerable level chronic boron intake on transcription factors

The mechanism of boron effect on human transcription and translation has not been fully understood. In the current study it was aimed to reveal the role of boron on the expression of certain transcription factors that play key roles in many cellular pathways on human subjects chronically exposed to low amounts of boron. The boron concentrations in drinking water samples were 1.57±0.06mg/l for boron group while the corresponding value for the control group was 0.016±0.002mg/l. RNA isolation was performed using PAX gene RNA kit on the blood samples from the subjects. The RNA was then reverse transcribed into cDNA and analyzed using the Human Transcription Factors RT2 Profiler™ PCR Arrays. While the boron amount in urine was detected as 3.56±1.47mg/day in the boron group, it was 0.72±0.30mg/day in the control group. Daily boron intake of the boron and control groups were calculated to be 6.98±3.39 and 1.18±0.41mg/day, respectively. The expression levels of the transcription factor genes were compared between the boron and control groups and no statistically significant difference was detected (P>0.05). The data suggest that boron intake at 6.98±3.39mg/day, which is the dose at which beneficial effects might be seen, does not result in toxicity at molecular level since the expression levels of transcription factors are not changed. Although boron intake over this level will seem to increase RNA synthesis, further examination of the topic is needed using new molecular epidemiological data.

Increased Thymic Cell Turnover under Boron Stress May Bypass TLR3/4 Pathway in African Ostrich.

Previous studies revealed that thymus is a targeted immune organ in malnutrition, and high-boron stress is harmful for immune organs. African ostrich is the living fossil of ancient birds and the food animals in modern life. There is no report about the effect of boron intake on thymus of ostrich. The purpose of present study was to evaluate the effect of excessive boron stress on ostrich thymus and the potential role of TLR3/4 signals in this process. Histological analysis demonstrated that long-term boron stress (640 mg/L for 90 days) did not disrupt ostrich thymic structure during postnatal development. However, the numbers of apoptotic cells showed an increased tendency, and the expression of autophagy and proliferation markers increased significantly in ostrich thymus after boron treatment. Next, we examined the expression of TLR3 and TLR4 with their downstream molecular in thymus under boron stress. Since ostrich genome was not available when we started the research, we first cloned ostrich TLR3 TLR4 cDNA from thymus. Ostrich TLR4 was close to white-throated Tinamou. Whole avian TLR4 codons were under purify selection during evolution, whereas 80 codons were under positive selection. TLR3 and TLR4 were expressed in ostrich thymus and bursa of fabricius as was revealed by quantitative real-time PCR (qRT-PCR). TLR4 expression increased with age but significantly decreased after boron treatment, whereas TLR3 expression showed the similar tendency. Their downstream molecular factors (IRF1, JNK, ERK, p38, IL-6 and IFN) did not change significantly in thymus, except that p100 was significantly increased under boron stress when analyzed by qRT-PCR or western blot. Taken together, these results suggest that ostrich thymus developed resistance against long-term excessive boron stress, possibly by accelerating intrathymic cell death and proliferation, which may bypass the TLR3/4 pathway. In addition, attenuated TLRs activity may explain the reduced inflammatory response to pathogens under boron stress.

Boric acid induces cytoplasmic stress granule formation, eIF2α phosphorylation, and ATF4 in prostate DU-145 cells.

Dietary boron intake is associated with reduced prostate and lung cancer risk and increased bone mass. Boron is absorbed and circulated as boric acid (BA) and at physiological concentrations is a reversible competitive inhibitor of cyclic ADP ribose, the endogenous agonist of the ryanodine receptor calcium (Ca+2) channel, and lowers endoplasmic reticulum (ER) [Ca2+]. Low ER [Ca2+] has been reported to induce ER stress and activate the eIF2α/ATF4 pathway. Here we report that treatment of DU-145 prostate cells with physiological levels of BA induces ER stress with the formation of stress granules and mild activation of eIF2α, GRP78/BiP, and ATF4. Mild activation of eIF2α and its downstream transcription factor, ATF4, enables cells to reconfigure gene expression to manage stress conditions and mild activation of ATF4 is also required for the differentiation of osteoblast cells. Our results using physiological levels of boric acid identify the eIF2α/ATF pathway as a plausible mode of action that underpins the reported health effects of dietary boron.

Boric acid activates PERK and ARE at physiological levels (372.2)

We first observed the chemopreventative nature of the plant nutrient boron as a significant association between intake and reduced risk of prostate cancer in the NHANES database and in cancer incidence across a groundwater boron gradient. Our observations have since been supported by others who showed boron intake is associated with reduced risk of lung cancer and cervical dysplasia, and lower prostate volume using ultrasound measurements. The underlying molecular mechanism involves the interaction of boric acid (BA) with cyclic ADP ribose with interruption of its endogenous Ca2+ signaling function. One of the downstream modes of action is activation of ATF4 by phosphorylation of eIF2α. Our present objective was to test the hypothesis that physiological levels of BA increase phosphorylation through PERK. We tested this using MEF WT and MEF PERK ‐/‐ cells. Treatment of MEF WT cells with10 μM BA resulted in an increase in ph‐eIF2α/total eIF2α at 0.5‐1 hours. This increase was not observed in 10 μM BA treated MEF Perk ‐/‐ cells over a 6 hour time course. To further test the hypothesis that BA activates PERK, we measured Nrf2 activation, another PERK dependent pathway in DU‐145 cells. Nrf2 activation leads to translocation from the cytoplasm to the nucleus where it acts as a transcription factor for the antioxidant response element (ARE). Using immunofluorescence we showed treatment with 10 μM BA resulted in Nrf2 translocation to the nucleus at 2 hours. We measured mRNA levels of three ARE genes (HMOX‐1, NQO1, and GCLC) using real time PCR. 10 μM BA treatment resulted in an increase in mRNA levels of all three genes at 2 hours a result that is consistent with the temporal pattern of PERK activation and Nrf2 translocation to the nucleus. These results provide further definition to the underlying processes involved in boron chemoprevention.

Boric Acid Activated Pathways in Prostate DU‐145 Cells

Boron intake is associated with reduced risk of prostate cancer and ultrasound determined gland volume. Boric acid (BA) at physiological concentrations is a reversible competitive inhibitor of cyclic ADP ribose (cADPR), depletes luminal endoplasmic reticulum Ca2+ and activates eIF2αP in DU‐145 prostate cells [Henderson and Eckhert 2009; 2006]. Our objective was to characterize the events that follow BA‐cADPR interaction. Treatment [10 μM BA] was followed by a dose dependent expansion of the ER and time dependent formation of TIA‐1 positive stress granules, decrease in global protein synthesis, and activation of the eIF2α/Grp78/ATF4 integrative stress pathway and the ATF6 branch of the unfolded protein response. BA increased expression of ATF4 downstream genes GADD34 and HERP and their respective proteins. CHOP, a pro‐apoptotic protein was decreased by BA treatment a result that is consistent with survival and differentiation. BA increased cytoplasmic ATF6 protein, its movement into the nucleus and downstream proteins Grp78, Grp94, calreticulin and XBP1. Cleavage of XBP1, an indicator of IRE1 activation, was not observed. HERP and EDEM1 mRNA were significantly up‐regulated by BA treatment. Our results extend current knowledge of the BA effect from rapid dose dependent inhibition of cADPR to time dependent activation of pathways known to be expressed in tissues affected by boron status. Funded by payments for teaching.

Boron as Testicular Toxicant in Mice (Mus domesticus)

SUMMARY: It has been reported that boron causes changes in various systems, including the male reproductive system. Residents in some towns in northern Chile were consuming a few years ago in the drinking water 20 times more than the amount established as permissible limit by WHO. This study evaluates the effects in an animal model of high intake of boron on the testis. Boron was administered in the drinking water. Twenty male mice (Mus domesticus), sexually mature, were used, divided into 2 groups: the experimental group was given Boron at a dose of 12 mg/L, and the control group 0.6 mg/L, for 42 days. Sections of testis were obtained for: HE staining (Morphometry and Histopathology), Immunohistochemistry (Cox-2), Mallory and Picrosirious stain (evaluation of tunica albuginea). The results indicate that ingestion of a dose of 12 mg Boron/L produces vacuolization, tubular epithelial desquamation and tamponade. Morphometry revealed decreased tubular diameter and epithelial height and lumen diameter and increased interstitial area in the exposed group. Immunodetection of COX-2 was positive in high percentage of tubules in the intoxicated group. The tunica albuginea was thinner, with decreased percentage of type I collagen fibers and an increase in the percentage of type III collagen fibers in animals exposed to boron in contrast to the control group. Exposure to critical levels of boron produces severe histopathological changes in the testis, altering morphometric parameters and causing overexpression of Cox-2. Finally, evaluation of collagen fibers suggests that Boron produced a degradation of the collagen of the tunica albuginea, causing a decrease in the thickness of it and altering the percentage ratio collagen I/collagen III, a process called collagenolysis. ˚

The effect of supplementation of calcium, vitamin D, boron, and increased fluoride intake on bone mechanical properties and metabolic hormones in rat

Evidence indicates that optimal nutrition plays a role in bone formation and maintenance. Besides major components of mineralization such as calcium, phosphorus, and vitamin D, other nutrients like boron and fluoride have beneficial role, too. In this study, 34 male Wistar rats were divided into five groups: control diet, fluoride, fluoride + boron, fluoride + calcium + vitamin D, and fluoride + boron + calcium + vitamin D. Boron equal to 1.23 mg, calcium and vitamin D equal to 210 mg + 55 IU and fluoride equal to 0.7 mg/rat/day was added to their drinking water for 8 weeks. Plasma blood samples and bones were collected. Findings are evidence that fluoride + boron intake revealed significant positive effects on bone mechanical properties and bone metabolic hormones. These findings suggest that combined intake of these two elements has beneficial effects on bone stiffness and breaking strength comparing to even calcium + vitamin D supplementation. This evidence dealing with health problems related to bone and skeletal system in humans should justify further investigation of the role of boron and fluoride with other elements in relation to bone.

Seasonal Variation of Boron and Fluoride in Tilapia nilotica from an Egyptian Fish Farm in Relation to Human Health Hazard Assessment

ABSTRACT This study evaluated the seasonal accumulation of boron and fluoride in different tissues of a common edible fish, Tilapia nilotica, from an Egyptian fish farm as well as their hazard to human health. Among all the determined fish tissues, brain, liver, and bone were the ones that accumulated the highest boron and fluoride contents. Interestingly, flesh tissue showed the lowest boron and fluoride concentrations (0.30 ± 0.06 and 2.50 ± 1.57 μg/g, respectively). Statistical analyses using Pearson correlation matrix and multiple regression procedures indicated that boron accumulation was highest amongst flesh, liver, brain, and bone tissues. Additionally, fluoride content in water affects its abundance in the different fish tissues: flesh, gills, bone, and skin. Human hazard assessment of fluoride and boron from water, sediment, and fish flesh tissue was studied using calculations that considered chronic daily intake from water, sediment, and fish; chronic exposure from dermal contact and ingestion of water; and fish as well as a single acute human dose. These calculations indicated that the consumption of Tilapia nilotica is still safe as regards boron intake, but for fluoride, it may pose a hazard to human health in the long term.

Dietary boron intake does not change the ischemic tolerance and preconditioning response in isoproterenol-induced myocardial injury in healthy rats

Boron is important for many enzymes, most of which also have a role in the ischemic tolerance of the myocardium. We aimed to evaluate the influence of dietary boron intake on ischemic tolerance in a rat model. Materials and methods: Rats were divided into 3 groups according to the ischemia protocol: Sham (S) (n = 20 total), ischemia only (Isc-only) (n = 40 total), and remote ischemic preconditioning + ischemia (RIPC+Isc) (n = 40 total) groups. These 3 groups were further divided into 4 according to the amount of daily dietary boron (

Growing Evidence for Human Health Benefits of Boron

Growing evidence from a variety of experimental models shows that boron is a bioactive and beneficial (perhaps essential) element for humans. Reported beneficial actions of boron include arthritis alleviation or risk reduction, bone growth and maintenance, central nervous system function, cancer risk reduction, hormone facilitation, and immune response, inflammation, and oxidative stress modulation. The diverse effects of boron indicate that it influences the formation and/or activity of an entity that is involved in many biochemical processes. Formation of boroesters with the ribose moiety of compounds involved in numerous reactions, such as S-adenosylmethionine and oxidized nicotinamide adenine dinucleotide (NAD+) might be the reason for boron bioactivity. Both animal and human data suggest that boron intakes should be >1.0 mg/d. Many people consume less than this amount. Thus, a low boron intake should be considered a health concern, which can be prevented by diets rich in fruits, vegetables, nuts, and pulses.

Development and Validation of a Method to Determine the Boron Isotopic Composition of Crop Plants

We present a comprehensive chemical and mass spectrometric method to determine boron isotopic compositions of plant tissue. The method including dry ashing, a three-step ion chromatographic boron-matrix separation, and (11)B/(10)B isotope ratio determinations using the Cs(2)BO(2)(+) graphite technique has been validated using certified reference and quality control materials. The developed method is capable to determine δ(11)B values in plant tissue down to boron concentrations of 1 mg/kg with an expanded uncertainty of ≤1.7‰ (k = 2). The determined δ(11)B values reveal an enormous isotopic range of boron in plant tissues covering three-quarters of the natural terrestrial occurring variation in the boron isotopic composition. As the local environment and anthropogenic activity mainly control the boron intake of plants, the boron isotopic composition of plants can be used for food provenance studies.

Determination of Boron Contents in Water Samples Collected from the Neelum valley, Azad Kashmir, Pakistan

Intake of boron from food and drinking water may pose a risk to the public health above a certain concentration level. Therefore, knowledge of boron concentration in drinking water and food items is essential. In this context, samples of drinking water were collected from natural springs of the Neelum valley, Azad Kashmir, hit by devastating earthquake in 2005. In these samples, boron concentration was determined using neutron-induced radiography technique. To do so, unknown water samples, along with standard of known boron dried on CR-39 detectors, were irradiated with thermal neutrons. After exposure, CR-39 detectors were etched in 6 M NaOH at 70°C. The tracks produced due to the alpha particles and (7)Li ions as a result of (10)B(n,α)(7)Li reaction were counted under an optical microscope. The tracks produced in theses samples were then related to the boron contents. The measured boron concentration in water samples was found to vary from 0.105 ± 0.005 to 0.247 ± 0.013 mg/l with an average value of 0.17 ± 0.04 mg/l, which are within the acceptable limits.

Genes mapping to boron tolerance QTL in barley identified by suppression subtractive hybridization

Boron tolerance is a quantitative trait controlled by multiple genes. Suppression subtractive hybridization was carried out on root cDNA from bulked boron tolerant and intolerant doubled haploid barley lines grown under moderate boron stress to identify genes associated with boron tolerance. One hundred and eleven clones representing known proteins were found to be up-regulated in the tolerant bulk upon boron stress. Nine clones were genetically mapped to previously reported boron tolerance QTL. These include a clone identical to the boron transporter gene Bot1 and a clone coding for a bromo-adjacent homology domain-containing protein, mapping to the 6H boron tolerance locus and co-segregating with reduced boron intake in a Clipper x Sahara-3771 mapping population. A third clone mapping to the 2H QTL region encoding an S-adenosylmethionine decarboxylase precursor was found to provide tolerance to high boron by heterologous expression. Yeast cells expressing Sahara SAMDC were able to grow on 15 mm boron solid media and maintained cellular boron concentrations at 13% lower than control cells expressing empty vector. The data suggest that an antioxidative response mechanism involving polyamines and the ascorbate-glutathione pathway in Sahara barley may provide an advantage in tolerating high soil concentrations of boron.

Micronutrients in Parenteral Nutrition: Boron, Silicon, and Fluoride

Boron may be beneficial for bone growth and maintenance, central nervous system function, and the inflammatory response, and silicon may be beneficial for bone maintenance and wound healing. Fluoride is not an essential element but amounts provided by contamination may be beneficial for bone strength. Fluoride toxicity may be a concern in parenteral nutrition. Further studies are warranted to determine whether there are optimal amounts of boron and silicon that should be delivered to typical and special population patients receiving parenteral nutrition. In addition, further studies are needed to determine whether providing the dietary guideline of adequate intake amounts of fluoride parenterally would prevent or treat parenteral nutrition osteopenia.

Stimulation of Bone Formation by Dietary Boron in an Orthopedically Expanded Suture in Rabbits

To evaluate the effects of dietary boron on bone regeneration in rabbits in response to expansion of the midpalatal suture during different retention periods. Twenty-eight 12-week-old New Zealand white male rabbits were separated into four equal groups: group 1 (B+10) and group 2 (B-10) had retention periods of 10 days with or without boron intake, respectively. Group 3 (B+20, with boron) and group 4 (B-20, without boron) were retained for 20 days. All groups had a 5-day expansion period. For both B+ groups, boron was prepared in distilled water and given to the rabbits during their (1) nursery phase (40 days), (2) expansion phase, and (3) retention period at a dosage of 3 mg/kg daily by oral gavage. Bone regeneration in the midpalatal suture was evaluated by a bone histomorphometric method, and the mineralized area (Md.Ar), fibrosis area (Fb.Ar), mineralized area/fibrosis area (Md.Ar/Fb.Ar), bone area (B.Ar) and osteoblast number (N.Ob) parameters were evaluated. Statistical analysis showed significant differences between groups for all investigated measurements. Md.Ar (P < .01), Md.Ar/Fb.Ar (P < .001), B.Ar (P < .01), and N.Ob (P < .01) parameters were increased and Fb.Ar (P < .01) was decreased in groups B+10 and B+20. No significant differences were observed during an additional 10-day retention period in all groups (P < .05). Boron has a positive effect on the early phase of bone regeneration of the midpalatal suture in response to expansion and may be beneficial in routine maxillary expansion procedures.

Boron and fish oil have different beneficial effects on strength and trabecular microarchitecture of bone

An experiment was performed to determine whether boron deprivation would adversely affect vertebra (trabecular) bone microarchitecture, and whether any adverse effect would be modified by dietary fatty acid composition. Female rats were fed diets containing 0.1 mg (9 μmol) boron/kg in a factorial arrangement with variables of supplemental boron at 0 (boron-deprived) or 3 (boron-adequate) mg (278 μmol)/kg and fat sources of 75 g safflower oil/kg or 65 g fish (menhaden) oil/kg plus 10 g linoleic acid/kg. After 6 weeks, six females per treatment were bred. Dams and pups continued on their respective diets through gestation, lactation, and after weaning. At age 21 weeks, the microarchitecture of the fourth lumbar vertebrae from 12 randomly selected pups from each treatment was determined by microcomputed tomography. Boron deprivation decreased bone volume fraction and increased trabecular separation and structural model index. Boron deprivation decreased trabecular thickness when the dietary oil was safflower. A three-point bending test for bone strength found that boron deprivation decreased the maximum force needed to break the femur. Feeding fish oil instead of safflower oil decreased connectivity density in vertebrae of boron-deficient but not in boron-adequate rats. Fish oil instead of safflower oil increased the maximum force to break and the bending moment of the femur, especially in rats fed adequate boron. The findings confirm that boron and fish oil are beneficial to cortical bone strength, and show that nutritional intakes of boron are beneficial for trabecular bone microarchitecture and influence the beneficial effects of fish oil on bone.

In vitro neutron irradiation of glioma and endothelial cultured cells

To fully develop its potential boron neutron capture therapy (BNCT) requires the combination of a suitable thermal/epithermal neutron flux together with a selective intake of 10B-boron nuclei in the target tissue. The latter condition is the most critical to be realized as none of the boron carriers used for experimental or clinical purposes proved at the moment an optimal selectivity for cancer cells compared to normal cells. In addition to complex physical factors, the assessment of the intracellular concentration of boron represent a crucial parameter to predict the dose delivered to the cancer cells during the treatment. Nowadays the dosimetry calculation and then the prediction of the treatment effectiveness are made using Monte Carlo simulations, but some of the model assumption are still uncertain: the radiobiological dose efficacy and the probability of tumour cell survival are crucial parameters that needs a more reliable experimental approach. The aim of this work was to evaluate the differential ability of two cell lines to selectively concentrate the boron-10 administered as di-hydroxyboryl-phenylalanine (BPA)-fructose adduct, and the effect of the differential boron intake on the damage produced by the irradiation with thermal neutrons; the two cell lines were selected to be representative one of normal tissues involved in the active/passive transport of boron carriers, and one of the tumour. Recent in vitro studies demonstrated how BPA is taken by proliferating cells, however the mechanism of BPA uptake and the parameters driving the kinetics of influx and the elimination of BPA are still not clarified. In these preliminary studies we analysed the survival of F98 and human umbilical vein endothelial cells (HUVEC) cells line after irradiation, using different thermal fluencies at the same level of density population and boron concentration in the growing medium prior the irradiation. This is first study performed on endothelium model obtained by a primary human cell line (HUVEC). The perspective application of this work is to develop a model able to foresee the effects produced by different combination of boron influx with a thermal neutron fluencies, applying a standardized radiobiological methodology, and in particular to continue the investigation of the radiobiological effects on the endothelium model as the main tissue involved in the transport of boronated molecules.

Evaluation of dietary status with respect to trace element intake from dry fruits consumed in Pakistan: a study using instrumental neutron activation analysis

Instrumental neutron activation analysis has been utilized for the quantification of 24 major, minor and trace elements in dried apricots (Prunus armeniaca), dates (Phoenix dectylifera), figs (Ficus carica) and raisins (Vitis vinifera) using a low-power reactor as the neutron source. The weekly intakes of aluminium, arsenic, boron, calcium, chlorine, cobalt, chromium, iron, mercury, potassium, sodium, magnesium, manganese, molybdenum, antimony, selenium and zinc have been calculated and compared with the Recommended Dietary Allowance/Estimated Safe and Adequate Dietary Intake values through consumption of 100 g dried fruit. Fairly adequate levels of calcium, cobalt, iron, potassium and magnesium were determined in these dried fruits while the contribution of chlorine, chromium, molybdenum and sodium to the Recommended Dietary Allowance was found to be insignificant. Apricot is a nutritionally rich source of potassium, magnesium and cobalt, while chlorine and manganese contents were found to be highest in dates. Figs are an ample source of calcium, iron, magnesium and manganese, whereas raisins provide the highest intake of chromium, molybdenum and sodium. The toxic element contents of these dry fruits are considerably below the tolerance limits.

Risk assessment of boron in glass wool insulation

Background, aim and scope Glass wools are man-made vitreous fibres, which consist principally of sodium, calcium and magnesium silicates, but may contain smaller amounts of other elements, including boron. The boron contents originate from the use of borates in the glass melting process as a glass former and a flux agent. During the production and application of glass wool insulation products, workers may legally be exposed to glass fibre up to the occupational limit value, commonly of 1 fibre/cm3. However, in practice, the fibre exposure will be at least ten times lower. Boron is a non-metallic element widely distributed in nature, where it occurs as boric acid, borates and borosilicates. Humans are mainly exposed to boron via vegetarian food and drinking water, mineral supplements and various consumer products. Boron is an essential element for plant growth, but the essentiality for humans is not proven, although intakes of trace amounts of the element seem to be useful for bone health and proper brain function; higher concentrations of boron, however, may be toxic. In relation to the European Union legislation on dangerous substances, an EU Expert Group has recommended classifying boric acid and borates with risk phrases for reproductive toxicity. The aim of this paper is to assess whether the new EU hazard classification of boron compounds should imply that glass wool products used for building insulation in the future should be labelled, “may impair fertility and cause harm to the unborn child”, because of the low boron content.