1. The measurement of boron in the environment and human hair in relation to Argentina, South America Sarah Hill* and Neil I. Ward Chemical Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK Introduction Boron deficiency in agriculture is common but toxicity is rare The environment in San José de Jachal in San Juan, Argentina suffers from high concentrations of boron, typically x10 higher than literature values Boron is not recognised as an essential element for animals or humans but is known to have various physiological effects 1-5 : -Macromineral metabolism, particularly Ca, Mg and P -Vitamin D utilisation -Inflammatory disease -Enzyme function Results and Discussion Conclusion References Many studies have investigated the effects of deficiency status and toxicity symptoms, predominantly under laboratory conditions Little is known about agricultural and human exposure through natural environmental pathways A preliminary study highlighted the need for further research in the human population through the monitoring of hair Methodology needed to be established for sample collection and digestion in-house Figure 1 Map of Argentina 6 Preliminary study results SampleConcentration (mg/kg) Hair San José de Jachal (n=2)2.28 (1.26 – 3.30) General Roca, Rio Negro (n=8) 0.43 (0.28 – 0.57) UK 7 0.23 (0.18 – 0.34) White wine – Chardonnay San Juan15.33 South Africa4.95 1.Institute of Medicine (2001) Dietary Reference Intakes For Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc, National Academic Press, Washington D.C., 510-521 2.F.H. Nielsen and T.R. Shuler (1992) Biol. Trace Elem. Res. 35, 225-237 3.S. Samman, M.R. Naghii, P.M. Lyons Wall and A.P.Verus (1998) Biol. Trace Elem. Res., 66(1-3), 227- 235 4.C.D. Hunt (1994) Environ. Health Perspect., 102(Suppl. 7), 35-43 5.R.E. Newnham (1994) Environ. Health Perspect., 102(Suppl. 7), 83-85 6.http://www.globosapiens.net/country/argentina_map.html 7.N. Hammond (2002) Elemental Status of Individuals from Rio Negro, Argentina: Use of Scalp Hair as a Biomarker of Environmental and Dietary Sources, MSc Thesis, University of Surrey 8.A. Stovell (1999) Trace Elements and Human Fertility, PhD Thesis, University of Surrey 9.G.S. Bañuelos, G.E. Cardon, T. Pflaum and S. Akohoue (1992) Comm. Soil Sci. Plant Anal., 23, 2383- 2397 10.C.D. Hunt and T.R. Shuler (1989) J. Micronutr. Anal., 6, 161-174 The results from the preliminary study are shown in Table 1. The hair samples were digested using nitric acid in a microwave and wine was simply diluted in ultrapure water. The analysis was performed by ICP-MS. General Roca in Rio Negro, Patagonia is a different region of Argentina, 550 miles to the south of San Juan (Figure 1). Table 1 Boron concentrations in hair and wine The size of the data in the preliminary study was small but showed the need for further investigation. Therefore a larger sample set from San José de Jachal and General Roca were obtained. Hair samples were collected with questionnaires about lifestyle and general health. Wine (Chardonnay and Cabernet Sauvignon) was collected from grape growers and manufacturers. Due to the unavailability of the microwave, an alternative hair digestion procedure was required. Boron can also be measured by a UV/Vis assay by the formation of a complex with azomethine-H and absorbance measured at 420 nm. The colour of the wine interferes with the detection of boron therefore requiring pre-treatment to eliminate this. 1.Dry ashing using 5% HNO 3 as an ashing aid (previously proven to reduce volatile losses for other elements 8 ) 2.Wet digestion using glass digestion tubes and heating block 9 with concentrated HNO 3 and 30% H 2 O 2 3.Wet digestion using PTFE beakers with lids on a hotplate 10 with concentrated HNO 3 and 30% H 2 O 2 Three different techniques were tested using unwashed and washed hair (IAEA method) and a certified reference material GBW 07601: Method development for hair digestion Preliminary work and lack of literature data highlighted the need for further investigation into the levels and effects of natural exposure to boron A suitable method for digestion of hair was established using nitric acid and hydrogen peroxide in PTFE beakers on a hotplate The effect of washing hair prior to digestion shows endogenous incorporation into the hair fibre via body absorption and assimilation A similar digestion approach was taken for wine, allowing boron measurement by a simple UV/Vis assay without interferences Further work: apply these methods to real samples from Argentina Table 2 Boron concentrations in hair using different digestion techniques mg/kg n=3 Dry ashingGlass tubesPTFE beakers MeanSDMeanSDMeanSD Unwashed 0.340.1412.024.536.541.18 Washed 0.130.0610.525.135.410.28 GBW 07601 0.230.017.815.043.671.26 % recovery28.0%211.5%150.1% Dry ashing consistently resulted in lower values compared with the other methods Washing the hair reduces the mean boron level suggesting the majority of B is endogenous rather than exogenous PTFE technique provides the best precision level and best % recovery Reference value for GBW 07601 is 1.3 mg/kg B confirming PTFE is in good agreement PTFE beakers with lids were used; 1 ml of wine and 1 ml of concentrated HNO 3 were allowed to stand overnight, 30% H 2 O 2 was added and placed on hotplate for 1 hr at 140°C, allowed to cool and diluted to 10 ml with ultrapure water, resulting in a colourless solution with no absorption at 420 nm. Spiked recoveries of 91–98% were achieved for chardonnay and 84–97% for cabernet sauvignon with this methodology. Method development for wine digestion General Roca Problems