ResearchPad - metallic-lead https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Environmental exposure to metal mixtures and linear growth in healthy Ugandan children]]> https://www.researchpad.co/article/elastic_article_14692 Stunting is an indicator of poor linear growth in children and is an important public health problem in many countries. Both nutritional deficits and toxic exposures can contribute to lower height-for-age Z-score (HAZ) and stunting (HAZ < -2).ObjectivesIn a community-based cross-sectional sample of 97 healthy children ages 6–59 months in Kampala, Uganda, we examined whether exposure to Pb, As, Cd, Se, or Zn were associated with HAZ individually or as a mixture.MethodsBlood samples were analyzed for a mixture of metals, which represent both toxins and essential nutrients. The association between HAZ and metal exposure was tested using multivariable linear regression and Weighted Quantile Sum (WQS) regression, which uses mixtures of correlated exposures as a predictor.ResultsThere were 22 stunted children in the sample, mean HAZ was -0.74 (SD = 1.84). Linear regression showed that Pb (β = -0.80, p = 0.021) and Se (β = 1.92, p = 0.005) were significantly associated with HAZ. The WQS models separated toxic elements with a presumed negative effect on HAZ (Pb, As, Cd) from essential nutrients with presumed positive effect on HAZ (Se and Zn). The toxic mixture was significantly associated with lower HAZ (β = -0.47, p = 0.03), with 62% of the effect from Pb. The nutrient WQS index did not reach statistical significance (β = -0.47, p = 0.16).DiscussionHigher blood lead and lower blood selenium level were both associated with lower HAZ. The significant associations by linear regression were reinforced by the WQS models, although not all associations reached statistical significance. These findings suggest that healthy children in this neighborhood of Kampala, Uganda, who have a high burden of toxic exposures, may experience detrimental health effects associated with these exposures in an environment where exposure sources are not well characterized. ]]> <![CDATA[Interest in “organic,” “natural,” and “additive-free” cigarettes after hearing about toxic chemicals in cigarette smoke]]> https://www.researchpad.co/article/5c897764d5eed0c4847d2b91

Introduction

The US Family Smoking Prevention and Tobacco Control Act requires the government to disseminate information about the toxic chemicals in cigarette smoke. We sought to understand how the descriptors “organic,” “natural,” or “additive-free” affect smokers’ interest in cigarettes in the context of information about chemicals in cigarette smoke.

Methods

Participants were a national probability sample of 1,101 US adult (ages ≥18) smokers recruited in 2014–2015. A between-subjects experiment randomized participants in a telephone survey to 1 of 4 cigarette descriptors: “organic,” “natural,” “additive-free,” or “ultra-light” (control). The outcome was expected interest in cigarettes with the experimentally assigned descriptor, after learning that 2 chemicals (hydrogen cyanide and lead) are in cigarette smoke. Experimental data analysis was conducted in 2016–2017.

Results

Smokers indicated greater expected interest in “organic,” “natural,” and “additive-free” cigarettes than “ultra-light” cigarettes (all p <.001) after learning that hydrogen cyanide and lead were in cigarette smoke. Smokers who intended to quit in the next 6 months expressed greater expected interest in the 4 types of cigarettes (“organic,” “natural,” “additive-free,” and “ultra-light”) compared to smokers not intending to quit (p <.001).

Conclusions

Smokers, especially those intending to quit, may be more inclined towards cigarettes described as “organic,” “natural,” and “additive-free” in the context of chemical information. An accumulating body of evidence shows that the US should fully restrict use of “organic” and “natural” descriptors for tobacco products as it has done for “additive-free” and “light” descriptors.

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<![CDATA[Trace metals in Northern New England streams: Evaluating the role of road salt across broad spatial scales with synoptic snapshots]]> https://www.researchpad.co/article/5c6dc9bfd5eed0c48452a11b

Mobilization of trace metals from soils to surface waters can impact both human and ecosystem health. This study resamples a water sample archive to explore the spatial pattern of streamwater total concentrations of arsenic, cadmium, copper, lead, and zinc and their associations with biogeochemical controls in northern New England. Road deicing appears to result in elevated trace metal concentrations, as trace metal concentrations are strongly related to sodium concentrations and are most elevated when the sodium: chloride ratio is near 1.0 (~halite). Our results are consistent with previous laboratory and field studies that indicate cation exchange as a metal mobilization mechanism when road salt is applied to soils containing metals. This study also documents associations among sodium, chloride, dissolved organic carbon, iron, and metal concentrations, suggesting cation exchange mechanisms related to road deicing are not the only mechanisms that increase trace metal concentrations in surface waters. In addition to cation exchange, this study considers dissolved organic carbon complexation and oxidation-reduction conditions affecting metal mobility from soils in a salt-rich environment. These observations demonstrate that road deicing has the potential to increase streamwater trace metal concentrations across broad spatial scales and increase risks to human and ecosystem health.

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<![CDATA[Characterization and mechanism of lead and zinc biosorption by growing Verticillium insectorum J3]]> https://www.researchpad.co/article/5c1028f0d5eed0c4842488ee

Verticillium insectorum J3 was isolated from a local lead-zinc deposit tailing, and its biosorption characteristics and reaction to the toxicities of different Pb(II) and Zn(II) concentrations were investigated. SEM, FTIR, a pH test and a desorption experiment were carried out to identify a possible mechanism. The biosorption of J3 presented an inhibition trend at low concentrations (25–75 mg L-1) and promotion at high concentrations (100–300 mg L-1). J3 absorbed Pb(II) prior to Zn(II) and produced alkaline substances, while mycelial and pellet morphology modifications were important for the removal of Pb(II) and Zn(II) under different stressful conditions (SEM results). Both intracellular accumulation and extracellular absorption may contribute to the removal of Pb(II) at lower concentrations (25–50 mg L-1), although mainly extracellular biosorption occurred at higher concentrations (75–300 mg L-1). However, Zn(II) bioaccumulation occurred at all concentrations assayed. Verticillium insectorum J3 may have evolved active defenses to alleviate the toxicity of heavy metals and proved to be a highly efficient biosorbent, especially for Pb(II) at high concentrations. This study is a useful reference for the development of biotreatment technologies to mitigate heavy metal waste.

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<![CDATA[IAA producing fungal endophyte Penicillium roqueforti Thom., enhances stress tolerance and nutrients uptake in wheat plants grown on heavy metal contaminated soils]]> https://www.researchpad.co/article/5c0993ced5eed0c4842ad9b0

Heavy metals contaminated soil is a serious environmental concern that has a negative impact on agriculture and ecosystem. Economical and efficient ways are needed to address this problem worldwide. In this regard, exploration and application of proficient microbial strains that can help the crop plants to thrive in agricultural soils that are greatly contaminated with heavy metals. The present study mainly focused on the effect of IAA producing endophytic fungi Penicillium ruqueforti Thom., on wheat plants cultivated in soil rich in heavy metals (Ni, Cd, Cu, Zn, and Pb). P. ruqueforti has induced great resistance in wheat inoculated plants grown in heavy metal contaminated soil. Application of the isolated strain of P. ruqueforti restricted the transfer of heavy metals from soil to the plants by secreting indole acetic acid (IAA). Furthermore, P. ruqueforti inoculated wheat seedlings watered with waste water had higher plant growth, nutrient uptake and low concentrations of heavy metals in shoot and roots. On the contrary, non-inoculated wheat plants under heavy metal stress had stunted growth with symptoms of chlorosis. From the results, it is concluded that P. ruqueforti inoculation can establish a symbiotic relationship with host plants, which is useful for phytostabilization of heavy metals or in other words helping the host crops to flourish through soil that are highly contaminated with heavy metals.

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<![CDATA[Effects of acute exposures of 2,4,6-trinitrotoluene and inorganic lead on the fecal microbiome of the green anole (Anolis carolinensis)]]> https://www.researchpad.co/article/5c12cf2dd5eed0c48491408e

Microbiome studies focused on ecologically relevant vertebrate models like reptiles have been limited. Because of their relatively small home range, fast maturation, and high fecundity, lizards are an excellent reptilian terrestrial indicator species. For this study we used the green anole, Anolis carolinensis, to assess the impact of military relevant contaminants on fecal microbiome composition. Fourteen day sub-acute exposures were conducted via oral gavage with 2,4,6-Trinitrotoluene (TNT) and inorganic lead at doses of 60 mg/kg and 20 mg/kg of body weight, respectively. Body weights and food consumption were monitored and fecal samples were collected for high-throughput 16S rRNA gene amplicon sequencing and analytical chemistry at days 0 and 15. At the end of the study, liver and gut were harvested for body burden data. Chemical analysis confirmed accumulation of TNT, TNT transformation products, and lead in liver tissue and fecal samples. Bacterial community analysis of fecal material revealed significant differences between day 0 and day 15 of TNT exposed anoles with an operational taxonomic unit (OTU) within the genus Erwinia representing 32% of the microbial community in TNT exposed anoles. Predictable changes in gut microbiome composition could offer an easily assayed, noninvasive biomarker for specific chemical exposure providing enhanced scientific support to risk assessments on military installations.

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