Biomonitoring for wide area surveying in landmine detection using honeybees and optical sensing

This project has received funding from NATO Science for Peace & Security under grant agreement MYP G5355, and the Engineering and Physical Sciences Research Council under EP/K503940/1.Humanitarian demining is a worldwide effort and the range of climates and environments prevent any one detection method being suitable for all sites, so more tools are required for safe and efficient explosives sensing. Landmines emit a chemical flux over time, and honeybees can collect the trace residues of explosives (as particles or as vapour) on their body hairs. This capability was exploited using a passive method allowing the honeybees to freely forage in a mined area, where trace explosives present in the environment stuck to the honeybee body, which were subsequently transferred onto an adsorbent material for analysis by a fluorescent polymer sensor. Potential false positive sources were investigated, namely common bee pheromones, the anti-varroa pesticide Amitraz, and the environment around a clean apiary, and no significant response was found to any from the sensor. The mined site gave a substantial response in the optical sensor films, with quenching efficiencies of up to 38%. A model was adapted to estimate the mass of explosives returned to the colony, which may be useful for estimating the number of mines in a given area.PostprintPeer reviewe

Honeybee-based biohybrid system for landmine detection

This research was funded in part by NATO Science for Peace and Security (SPS) Programme, project number SPS 985355, “Biological Method (Bees) for Explosive Detection”.Legacy landmines in post-conflict areas are a non-discriminatory lethal hazard and can still be triggered decades after the conflict has ended. Efforts to detect these explosive devices are expensive, time-consuming, and dangerous to humans and animals involved. While methods such as metal detectors and sniffer dogs have successfully been used in humanitarian demining, more tools are required for both site surveying and accurate mine detection. Honeybees have emerged in recent years as efficient bioaccumulation and biomonitoring animals. The system reported here uses two complementary landmine detection methods: passive sampling and active search. Passive sampling aims to confirm the presence of explosive materials in a mine-suspected area by the analysis of explosive material brought back to the colony on honeybee bodies returning from foraging trips. Analysis is performed by light-emitting chemical sensors detecting explosives thermally desorbed from a preconcentrator strip. The active search is intended to be able to pinpoint the place where individual landmines are most likely to be present. Used together, both methods are anticipated to be useful in an end-to-end process for area surveying, suspected hazardous area reduction, and post-clearing internal and external quality control in humanitarian demining.Publisher PDFPeer reviewe

137Cs in flowers, pollen and honey from the Republic of Croatia four years after the Chernobyl accident

137Cs concentration was measured in flowers, pollen and honey, samples of which were collected from the Republic of Croatia 4 years after the Chernobyl accident. Radioactivity of 137Cs was measured by gamma-spectrometry. Cesium in honey corresponds well with 137Cs contamination of territory in the Republic of Croatia. Activity of 137 Cs in pollen which is higher than in honey indicates that cesium behaves analogously to potassium. The results show that equal cesium concentration in the surface soil layer results in higher cesium activities in honey in the case of meadow flowers, ie honey bee pasture, than in cases when pasture is based on bush and tree flowers. Cesium activity average in honey, collected from the Republic of Croatia territory, is < 1 % of the permissible level of 600 Bq/kg

Dermal absorption of vaporous and liquid 2-methoxyethanol and 2-ethoxyethanol in volunteers.

OBJECTIVES: To estimate dermal absorption of vaporous and liquid 2-methoxyethanol (ME) and 2-ethoxyethanol (EE) in volunteers. METHODS: Five volunteers (two men and three women) were dermally exposed to vaporised and liquid ME and EE. Dermal exposure on an area of about 1000 cm2 (forearm and hand) to vapours of ME and EE (4000 mg/m3 ME and 3700 mg/m3 EE) lasted for 45 minutes. Duration of exposure to liquid ME and EE on an area of 27 cm2 (forearm) was 15 minutes. Dermal uptake was assessed by measurement of the main metabolites in urinary methoxyacetic acid (MAA) and ethoxyacetic acid (EAA). For each volunteer, excretion of metabolites was compared with a reference inhalatory exposure. RESULTS: Mean (SD) absorption rates of ME and EE vapour were 36 (11) and 19 (6) cm/h respectively. The mean (SD) absorption rates of the liquid ME and EE amounted to 2.9 (2.0) and 0.7 (0.3) mg/cm2.h. CONCLUSIONS: Vaporised and liquid ME and EE are readily absorbed through the skin. In the combined inhalatory and dermal exposure when whole body surface is exposed to vapour, the uptake through the skin is estimated to be 55% of the total uptake of ME and 42% of EE. Dermal uptake resulting from skin contact of both hands and forearms (about 2000 cm2) with liquid ME and EE for 60 minutes would exceed inhalatory uptake of the eight hour occupational exposure limit by 100 times at 16 mg/m3 of ME and 20 times at 19 mg/m3 of EE. The substantial skin uptake of ME and EE indicates that in assessing the health risks biological monitoring and use of biological exposure indices are preferable to environmental monitoring

Metabolism of styrene in the human liver in vitro: interindividual variation and enantioselectivity

1. The interindividual variation and enantioselectivity of the in vitro styrene oxidation by cytochrome P450 have been investigated in 20 human microsomal liver samples. Liver samples were genotyped for the CYP2E1*6 and CYP2E1*5B alleles. 2. Kinetic analysis indicated the presence of at least two forms of styrene-metabolizing cytochrome P450. The enzyme constants for the high-affinity component were subject to appreciable interindividual variation, i.e. Vmax1 ranged from 0.39 to 3.20 nmol mg protein(-1) min(-1) (0.96+/-0.63) and Km1 ranged from 0.005 to 0.03 mM (0.011+/-0.006). Inhibition studies with chemical inhibitors of CYP2E1, CYP1A2, CYP2C8/9 and CYP3A4 demonstrated that CYP2E1 was the primary enzyme involved in the high-affinity component of styrene oxidation. No relationship between the interindividual variation in Vmax1 and Km1 and the genetic polymorphisms of the CYP2E1 gene was found. 3. Cytochrome P450-mediated oxidation of styrene demonstrated a moderate enantioselectivity, with an enantiomeric excess (ee) of (S)-styrene oxide of 15% (range 4-27%) at low styrene concentration and an ee of (R)-styrene oxide of 7% (range -11 to +22%) at high styrene concentration. This points towards the involvement of at least two cytochrome P450, with different enantioselectivities. 4. The data indicate that cytochrome P450-mediated styrene oxidation is subject to considerable interindividual variation, but only to a moderate product enantioselectivit

Dermal absorption of vaporous and liquid 2-methoxyethanol and 2-ethoxyethanol in volunteers

To estimate dermal absorption of vaporous and liquid 2-methoxyethanol (ME) and 2-ethoxyethanol (EE) in volunteers. Five volunteers (two men and three women) were dermally exposed to vaporised and liquid ME and EE. Dermal exposure on an area of about 1000 cm2 (forearm and hand) to vapours of ME and EE (4000 mg/m3 ME and 3700 mg/m3 EE) lasted for 45 minutes. Duration of exposure to liquid ME and EE on an area of 27 cm2 (forearm) was 15 minutes. Dermal uptake was assessed by measurement of the main metabolites in urinary methoxyacetic acid (MAA) and ethoxyacetic acid (EAA). For each volunteer, excretion of metabolites was compared with a reference inhalatory exposure. Mean (SD) absorption rates of ME and EE vapour were 36 (11) and 19 (6) cm/h respectively. The mean (SD) absorption rates of the liquid ME and EE amounted to 2.9 (2.0) and 0.7 (0.3) mg/cm2.h. Vaporised and liquid ME and EE are readily absorbed through the skin. In the combined inhalatory and dermal exposure when whole body surface is exposed to vapour, the uptake through the skin is estimated to be 55% of the total uptake of ME and 42% of EE. Dermal uptake resulting from skin contact of both hands and forearms (about 2000 cm2) with liquid ME and EE for 60 minutes would exceed inhalatory uptake of the eight hour occupational exposure limit by 100 times at 16 mg/m3 of ME and 20 times at 19 mg/m3 of EE. The substantial skin uptake of ME and EE indicates that in assessing the health risks biological monitoring and use of biological exposure indices are preferable to environmental monitorin

Metabolic capacity and interindividual variation in toxicokinetics of styrene in volunteers

The aim of the present study was to assess the interindividual variation in styrene toxicokinetics and to correlate this variation with the individual metabolic capacity for cytochrome P450 (CYP), CYP2E1, CYP1A2 and CYP2D6. Twenty male volunteers were exposed on separate occasions to 104+/-3 and 360+/-20 mg/m3 of styrene for 1 h while performing 50 W physical exercise on a bicycle ergometer. Styrene concentrations in blood and mandelic (MA) and phenylglyoxylic acid (PGA) in urine were measured. The metabolic capacity was assessed by phenotyping with chlorzoxazone (CYP2E1), caffeine (CYP1A2), dextromethorphan (CYP2D6) and antipyrine (CYP450). In addition, for the main styrene-metabolising enzyme, CYP2E1, genotyping for the genetic polymorphisms of the gene was performed. The average pulmonary retention of styrene was 62 +/- 7% at both exposure concentrations, and the 24-h excretion of MA and PGA accounted for 58% of the dose at both concentrations. The interindividual variation in styrene kinetics ranged from 19% for the terminal half-life (t(1/2,beta)) of styrene to 41% for the cumulative excretion of MA and PGA. However, no correlation between the apparent blood clearance of styrene (CLapp), t(1/2,beta) of styrene or excretion of MA and PGA on one hand, and the individual metabolic capacity on the other hand was found. Although other explanations cannot be excluded, this lack of correlation might be due to the high apparent blood clearance (1.4 l/min) of styrene, indicating that styrene metabolism is liver-blood-flow-dependen

Dermal absorption of cis-1,3-dichloropropene vapour: human experimental exposure

1. The relevance of skin absorption of cis-1,3-dichloropropene (cis-1,3-DCP) vapour as a route of entry compared to inhalatory uptake has been assessed in human volunteers under controlled exposure conditions. 2. Five adults (four males and one female) were dermally exposed on the forearm and hand during 45 min to 86 mg/m3 cis-1,3-DCP. 3. Dermal uptake was assessed by determination of the main cis-1,3-DCP metabolite in urine: the mercapturic acid conjugate of cis-1,3-DCP (cis-1,3-DCP-MA). 4. When whole-body dermal exposure to vapour is compared to inhalatory exposure, the uptake through the skin is estimated to be about 2-5% of the inhalatory absorptio

40

Specific activities of 40K, 134Cs and 137Cs in pollen, honey and in the first 25 cm of the surface soil layer were measured by gamma-spectrometry. Specific activity of 40K in pollen is about 1 order of magnitude higher than in honey. A 40K soil-to-pollen transfer coefficient (TC( 40K)) of 0.436 ± 0.054 and a soil-to-honey transfer coefficient TC(40K) of 0.052 ± 0.008 were calculated as the mean of their respective values in 26 different segments of soil profile. Both parameters have very stable values over time as well as through different segments of vertical soil profile. 134Cs and 137Cs specific activities in pollen and honey decrease with time, resulting in a decrease of 137Cs soil-to-honey transfer factors (Tf(137Cs)) over time. The increase of the soil-to-honey Tf(137Cs) with increasing soil depth is a consequence of vertical distribution of 137Cs in soil. Soil-to-honey T f(137Cs) values are highest in meadow and mixed honey types and lowest in bush/tree honey. Similar trends are found for both Tf(134Cs) and Tf(137Cs). The results presented here indicate the importance of the caesium inventory in soil segments where plant root systems are developed

Gas chromatography-electron capture determination of styrene-7,8-oxide enantiomers

The enantiomers of styrene-7,8-oxide (phenyloxirane, SO) were determined using a method based on base catalysed hydrolysis with sodium methoxide. The oxirane ring opening resulted in formation, without racemisation, of the enantiomeric pairs of the two regional isomers, 2-methoxy-1-phenylethanol and 2-methoxy-2-phenylethanol. The structure of these regional isomers was confirmed by gas chromatography-mass spectrometry (GC-MS) and proton nuclear magnetic resonance (1H-NMR). To improve sensitivity of determination, the formed methoxy alcohols were subsequently derivatised with pentafluoropropionic anhydride enabling electron capture detection. This derivatization proceeded also without racemisation and the formed pentafluoropropionyl derivatives were separated on two serially coupled columns, a non-chiral AT 1705 and a chiral CP Chirasil-Dex-CB. As internal standard 2S,3S-(-)-2-methyl-3-phenyloxirane was used. The limit of quantitation of the method was 0.2 microM. The repeatability of the method was assessed at two concentration levels (2.5 and 25 microM) and ranged from 6 to 9% for both enantiomers. The method was applied to the determination of the rate and enantioselectivity of the cytochrome P-450 dependent oxidation of styrene to SO enantiomers in human liver microsome