Water Stress Influences Phytoestrogen Levels in Red Clover (Trifolium pratense) but Not Kura Clover (T. ambiguum).

Some forage legumes synthesize phytoestrogens. We conducted a glasshouse study to investigate how water stress (drought and waterlogging) influences phytoestrogen accumulation in red clover and kura clover. Compared to the red clover control, the 20 day drought resulted in an over 100% increase in the phytoestrogens formononetin and biochanin A, which together accounted for 91-96% of the total phytoestrogens measured. Waterlogging resulted in elevated concentrations of daidzein, genistein, and prunetin but not formononetin or biochanin A. Concentrations of phytoestrogens in kura clover were low or undetectable, regardless of water stress treatment. Leaf water potential was the most explanatory single-predictor of the variation in concentrations of formononetin, biochanin A, and total phytoestrogens in red clover. These results suggest that drought-stressed red clover may have higher potential to lead to estrogenic effects in ruminant livestock and that kura clover is a promising alternative low- or no-phytoestrogen perennial forage legume.

Can the KG1 cell line be used as a model of dendritic cells and discriminate the sensitising potential of chemicals?

The KG1 myeloid leukaemia was used as source of dendritic cells (DC) to discriminate between respiratory and contact sensitising chemicals. A cocktail of cytokines was used to differentiate KG1 to dendritic like cells (termed dKG1) and the effects of nine chemicals (respiratory and contact sensitisers) and an irritant control on surface marker expression, 'antigen presenting' function and cytokine expression investigated. The stability of these chemicals when dissolved was characterised using MALDI ToF MS. A Hill plot model was used with the cellular viability data to quantify the lethal dose 50% (LD50) and a maximum sub toxic concentration of each chemical defined. Cytokine expression by the treated dKG1 was quantified using multiplex immunobead analysis. Whilst dKG1 cells were morphologically similar to DCs, expression of specific surface markers was not typical for DCs derived from healthy precursor cells. When the chemicals were applied at defined sub toxic doses no effects on dKG1 phenotype, function, or cytokine expression, attributable to the sensitisation properties were discriminated. However, dKG1 cells were much more sensitive to the toxic effects of these chemicals compared to the parent KG1 cells. Only 4 of the 9 chemicals tested were stable when dissolved indicating that the effect of sensitising chemicals on antigen presenting cells may be related to species other than the parent compound.

Increased productivity of a cover crop mixture is not associated with enhanced agroecosystem services.

Cover crops provide a variety of important agroecological services within cropping systems. Typically these crops are grown as monocultures or simple graminoid-legume bicultures; however, ecological theory and empirical evidence suggest that agroecosystem services could be enhanced by growing cover crops in species-rich mixtures. We examined cover crop productivity, weed suppression, stability, and carryover effects to a subsequent cash crop in an experiment involving a five-species annual cover crop mixture and the component species grown as monocultures in SE New Hampshire, USA in 2011 and 2012. The mean land equivalent ratio (LER) for the mixture exceeded 1.0 in both years, indicating that the mixture over-yielded relative to the monocultures. Despite the apparent over-yielding in the mixture, we observed no enhancement in weed suppression, biomass stability, or productivity of a subsequent oat (Avena sativa L.) cash crop when compared to the best monoculture component crop. These data are some of the first to include application of the LER to an analysis of a cover crop mixture and contribute to the growing literature on the agroecological effects of cover crop diversity in cropping systems.

Comparison of urinary thallium levels in non-occupationally exposed people and workers.

PURPOSE: To determine a reference background urinary thallium level; to compare urinary thallium data from workers to this background level; to investigate factors affecting these levels and whether creatinine correction is appropriate. METHODS: Urine samples from non-occupationally exposed people (n = 273, from 113 individuals) and workers (n = 896, from 447 individuals) were analysed for thallium by ICP-MS. A reference background level was calculated, defined as the 95th percentile value of a non-occupationally exposed population. Worker data were divided into two subsets: thallium workers (those who work directly with thallium or its compounds) and general workers; and compared to the background level. Bayesian linear mixed effects modelling was used to investigate factors affecting urinary thallium concentration and the efficacy of creatinine correction for the determination of urinary thallium. RESULTS: The reference background urinary thallium level is 0.27 µmol/mol creatinine (creatinine-corrected) or 0.40 µg/l (uncorrected). Median values were 0.11 µmol/mol creatinine or 0.17 µg/l for non-occupationally exposed people, 0.12 µmol/mol creatinine or 0.20 µg/l for general workers and 0.19 µmol/mol creatinine or 0.41 µg/l for thallium workers. Variation was lower in creatinine-corrected models. Nine per cent of samples from general workers and 39 % of samples from thallium workers exceeded the creatinine-corrected background level. By 2010, 90 % of all workers had urinary thallium levels below the 95th percentile reference background level. CONCLUSIONS: Urinary thallium concentrations were higher in thallium workers than non-occupationally exposed people and general workers. Creatinine correction is appropriate.

Trends in blood lead levels in UK workers, 1995-2007.

OBJECTIVES: This study evaluated blood lead data (including zinc protoporphyrin (ZPP) and haemoglobin levels) collected at the UK's Health and Safety Laboratory (HSL) in order to determine temporal changes in occupational exposure to lead between 1995 and 2007. METHODS: A total of 20,889 blood lead measurements and accompanying ZPP and haemoglobin results from 8810 workers at 972 companies from routine samples received by HSL over the period 1995-2007 were analysed. Time trends in blood lead levels for each industry sector were estimated using Bayesian mixed effects modelling. RESULTS: Reductions in median blood levels over the period 1995-2007 were seen in every sector except for those samples forwarded by occupational health providers, and range from 1.6% per year for workers in the smelting industry to 12% per year for workers in pottery and glazing industries. An overall reduction of 3.1% per year across all industries was determined. The percentage of results above the current UK suspension limit of 60 microg/dl fell from 4.8% in 1995 to 0.6% in 2007. ZPP and blood lead exhibited a strong association, but no significant correlation was found between blood lead and haemoglobin. CONCLUSIONS: Occupational exposure to lead has fallen across UK industries in recent years, although it remains substantially above background levels. There is evidence that many workers are exposed to elevated lead levels over a long period of time and this deserves renewed consideration now that inorganic lead has been reclassified as a probable human carcinogen.

Field experiments to assess approaches for spray drift incident investigation.

BACKGROUND: Spray trials were conducted to determine the variation in primary spray drift deposition between trials under very similar conditions, in order to assess the feasibility of developing a computational tool to aid post-event investigations of pesticide spray incidents. Pesticide deposition was examined by analysis of filter paper and vegetation samples. RESULTS: Considerable variation in the drift profile was found. The overall estimate of the spray drift decay term was -1.13 (95% confidence interval -1.02 to -1.24), with statistically significant differences between plots. Variation in the drift profile between neighbouring essentially identical plots indicates the variation in deposition that might be expected over small distances. Vegetation samples were found to have considerably lower capture efficiency than filter papers. Importantly, degradation of pesticides was found to have little effect on the pesticide drift profile over a 14 day period. CONCLUSIONS: The levels of spatial variation in spray drift deposits between runs and plots observed in this study suggest serious limitations to the inferences that may be drawn from limited numbers of post-incident samples. In particular, they would limit inferences about the spray conditions that could be drawn from an estimate of the drift profile derived from limited post-incident samples.

The effects of nickel and chromium on human keratinocytes: differences in viability, cell associated metal and IL-1alpha release.

This study was carried out to assess the effects of chromium and nickel upon isolated keratinocytes as an in vitro model of human skin. Keratinocytes were isolated from healthy volunteer skin samples of unknown metal sensitivity (n=10) and were compared with cells from patient biopsies of known metal sensitivity (n=7). Cells were dosed with a concentration range of nickel and chromium (0-10,000 microM) and cellular mitochondrial activity, viability, metal uptake and cytokine release were measured. Responses of primary versus passaged keratinocytes were also compared. Toxicity data from primary and passaged keratinocytes was statistically analysed by the non-linear Hill Plot model. Results showed that hexavalent chromium was significantly more cytotoxic, associated more with keratinocytes and induced a dose dependant release of IL-1alpha compared to nickel. Significant differences were observed between primary and passaged keratinocytes with regard to the toxicity of chromium and nickel and variation of response. No differences were observed in the cytotoxicity or cytokine release induced by chromium or nickel for the known sensitised biopsy patient samples (n=4) compared to patch test negative controls (n=3). The results from this study suggest human keratinocytes in vitro respond very differently to chromium and nickel.

Task-based dermal exposure models for regulatory risk assessment.

The regulatory risk assessment of chemicals requires the estimation of occupational dermal exposure. Until recently, the models used were either based on limited data or were specific to a particular class of chemical or application. The EU project RISKOFDERM has gathered a considerable number of new measurements of dermal exposure together with detailed contextual information. This article describes the development of a set of generic task-based models capable of predicting potential dermal exposure to both solids and liquids in a wide range of situations. To facilitate modelling of the wide variety of dermal exposure situations six separate models were made for groupings of exposure scenarios called Dermal Exposure Operation units (DEO units). These task-based groupings cluster exposure scenarios with regard to the expected routes of dermal exposure and the expected influence of exposure determinants. Within these groupings linear mixed effect models were used to estimate the influence of various exposure determinants and to estimate components of variance. The models predict median potential dermal exposure rates for the hands and the rest of the body from the values of relevant exposure determinants. These rates are expressed as mg or microl product per minute. Using these median potential dermal exposure rates and an accompanying geometric standard deviation allows a range of exposure percentiles to be calculated.

Default values for assessment of potential dermal exposure of the hands to industrial chemicals in the scope of regulatory risk assessments.

Dermal exposure needs to be addressed in regulatory risk assessment of chemicals. The models used so far are based on very limited data. The EU project RISKOFDERM has gathered a large number of new measurements on dermal exposure to industrial chemicals in various work situations, together with information on possible determinants of exposure. These data and information, together with some non-RISKOFDERM data were used to derive default values for potential dermal exposure of the hands for so-called 'TGD exposure scenarios'. TGD exposure scenarios have similar values for some very important determinant(s) of dermal exposure, such as amount of substance used. They form narrower bands within the so-called 'RISKOFDERM scenarios', which cluster exposure situations according to the same purpose of use of the products. The RISKOFDERM scenarios in turn are narrower bands within the so-called Dermal Exposure Operation units (DEO units) that were defined in the RISKOFDERM project to cluster situations with similar exposure processes and exposure routes. Default values for both reasonable worst case situations and typical situations were derived, both for single datasets and, where possible, for combined datasets that fit the same TGD exposure scenario. The following reasonable worst case potential hand exposures were derived from combined datasets: (i) loading and filling of large containers (or mixers) with large amounts (many litres) of liquids: 11,500 mg per scenario (14 mg cm(-2) per scenario with surface of the hands assumed to be 820 cm(2)); (ii) careful mixing of small quantities (tens of grams in <1l): 4.1 mg per scenario (0.005 mg cm(-2) per scenario); (iii) spreading of (viscous) liquids with a comb on a large surface area: 130 mg per scenario (0.16 mg cm(-2) per scenario); (iv) brushing and rolling of (relatively viscous) liquid products on surfaces: 6500 mg per scenario (8 mg cm(-2) per scenario) and (v) spraying large amounts of liquids (paints, cleaning products) on large areas: 12,000 mg per scenario (14 mg cm(-2) per scenario). These default values are considered useful for estimating exposure for similar substances in similar situations with low uncertainty. Several other default values based on single datasets can also be used, but lead to estimates with a higher uncertainty, due to their more limited basis. Sufficient analogy in all described parameters of the scenario, including duration, is needed to enable proper use of the default values. The default values lead to similar estimates as the RISKOFDERM dermal exposure model that was based on the same datasets, but uses very different parameters. Both approaches are preferred over older general models, such as EASE, that are not based on data from actual dermal exposure situations.