Movement and persistence of aldicarb in certain soils

When the rate of movement and the persistence of aldicarb in 4 types of soils were investigated in laboratory and field studies some leaching was detected in coarse sand; however, leaching was quite limited in clay loam and muck soils. These data indicated that aldicarb degraded quite rapidly in the selected soils and most of the applied radioactivity volatilized from these soil columns as¹⁴CO₂. The evolution of¹⁴CO₂ from the treated soil suggested severe degradation of the aldicarb molecule and consequently provided indirect evidence against the accumulation of significant quantities of toxic metabolites in the soil types evaluated. Under field conditions this toxicant appeared to have a half-life of about 7 days in loam soil.This research was conducted in cooperation with the Texas Agricultural Experiment Station. Mention of a pesticide or a proprietary product in this paper does not constitute a recommendation or an endorsement of this product by the U. S. Department of Agriculture.     

Movement and persistence of aldicarb in certain soils

When the rate of movement and the persistence of aldicarb in 4 types of soils were investigated in laboratory and field studies some leaching was detected in coarse sand; however, leaching was quite limited in clay loam and muck soils. These data indicated that aldicarb degraded quite rapidly in the selected soils and most of the applied radioactivity volatilized from these soil columns as 14CO2. The evolution of 14CO2 from the treated soil suggested severe degradation of the aldicarb molecule and consequently provided indirect evidence against the accumulation of significant quantities of toxic metabolites in the soil types evaluated. Under field conditions this toxicant appeared to have a half-life of about 7 days in loam soil.     

Leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans in fly ash from municipal solid waste incinerators to a water system

In order to predict how much polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) are leached from fly ash by rain water when fly ash is disposed, leaching of PCDDs/Fs from a fly ash obtained from a municipal solid waste incinerator (MSWI) was investigated by packing the ash in a column and eluting with water. In the beginning of the elution, PCDDs/Fs associated with water-soluble particulates in the ash were eluted, whereas in the latter half, those associated with water slightly soluble particles were eluted, judging from the comparison of PCDDs/Fs in eluate fractions with those transferred to solutions from the original ash by stepwise batch methods with water and 2N hydrochloric acid.The amounts of PCDDs/Fs eluted from the ash column were 2.9% and 1.7% of those extracted from the original ash, respectively, while large amounts of PCDDs/Fs were contained in the fly ash in the column after the elution, suggesting that PCDDs/Fs in water-insoluble particulates of the ash would not be eluted by water.     

Removal of nitrosamines from waste water by potassium ferrate oxidation

Potassium ferrate (K2FeO4) is useful in the advanced treatment of waste water. Additional evidence of this capability is presented in this study. Potassium ferrate is a very strong oxidant and is highly soluble in water. The nitrosamine studied in this work was toxic and was a potent pancreatic tumorigen in laboratory animals. Nitrosamines, which are potent carcinogens, are widespread throughout the environment and can be eliminated from waste water effluent by the action of potassium ferrate. Potassium ferrate and the nitrosamine was placed in aqueous solution and allowed to react to completion. Analysis by photospectroscopy revealed that the nitrosamine was completely degraded. This result suggests that potassium ferrate is useful for decontamination of some waste water collections.     

Dissipation and degradation of ALAR® in soils under greenhouse conditions

The rate of dissipation of ALAR^-14C (succinic acid 2,2-dimethylhydrazide) was studied on four soils under greenhouse conditions. The half-life of ALAR was 3 to 4 days on all soils.Data derived from experiments with sterilized sandy loam indicate that microbial degradation is the major route of dissipation of ALAR from soil. Trapping experiments showed that the major degradation product from ALAR (N-methyl-¹⁴C) is¹⁴CO₂, which is liberated in amounts of up to 84% in 14 days. Of the¹⁴C remaining on soil, most is associated with soil organic matter.     

An analysis of risk from exposure to aldicarb using immune response of nonuniform populations of mice

The immunomodulation response of mice to low levels of aldicarb in drinking water was investigated in four series of studies. The splenic plaque forming cell (PFC) response to red sheep cells were measured for treatment levels of 0.01 to 1,000 ppb (g/kg). Based on their beginning and end body weights, the animal populations were uniform in all series of tests, but based on their net body weights and PFC counts they were highly nonuniform in the 30 and 60 day tests and uniform in the 90 and 180 day tests.The mean PFC counts for animals in each treatment were calculated and compared with the mean PFC counts for animals in the controls in all four series of tests. This approach ignores the variability and nonuniformity in the animal population. The outcomes using this approach were stimulatory for the 30 and 60 day tests and inhibitory for the 90 and 180 day tests.An alternative approach was developed based on the analysis of the distributions of the relative PFC counts of each animal in a treatment with each animal in a control, and specifically addresses the variability and nonuniformity in animal population as integral parts of the analysis. The distribution peaks were estimated by maximum likelihood and kernel/bootstrap procedures and were used to summarize the tests. The outcomes were consistently inhibitory, indicating immune suppression. The outcome of this approach converged to the outcome of the mean PFC approach for the 90 and 180 day tests where the animal populations were uniform.     

Changes in eye blink frequency as a measure of trigeminal stimulation by exposure to limonene oxidation products,isoprene oxidation products and nitrate radicals

Objectives To measure eye blink frequency as a measure of trigeminal stimulation of the eye. Human subjects were exposed to oxidation mixtures representative of reactive indoor pollutants and clean air, from which relative changes in blink frequencies were measured.Method Male subjects (n=8) were exposed for 20 min to limonene oxidation products (LOPs), isoprene oxidation products (IOPs), nitrate radicals (NO₃), their residual reactants, and clean air at 20% relative humidity. A baseline blink frequency was measured prior to and following each exposure (2×8 min). The subjects were exposed locally in the non-dominant eye and single blind in random order. Blinking was video-recorded and evaluated for full sessions of 36 min while the subjects viewed an educational film. The initial terpene concentrations were one to two orders of magnitude higher than mean indoor concentrations.Results The mean blink frequency increased significantly during subjects exposure to gas-phase oxidation products at lower part-per-billion (ppb) levels of LOPs, 42% (P<0.0001) and NO₃, 21% (P<0.022), compared with that at baseline. Neither the residual reactants nor clean air changed the blink frequency significantly. The findings coincided with qualitative reporting of weak eye irritation symptoms.Conclusions Changes in blink frequency appear to be a promising measure of trigeminal stimulation from exposure to eye irritants in ppb levels. Gaseous products of limonene and ozone, and reactive radicals may cause eye irritation indoors.     

Leaching of lead from ceramics

Summary The amount of lead leached from various glazed ceramic was determined by extraction with 5% acetic acid for one hour at 85°C. All commercial ceramic items, both domestic and imported, were below the FDA standard of 7 mg/liter lead in the extractant. On the other hand, almost 60% of the domestic homemade ceramic items exceeded FDA standards. Comparison with previous studies show significant reduction in lead leaching from commercial ceramic containers. However, homemade ceramic items continue to pose a potential hazard of excessive lead release.     

Increased serum levels of advanced oxidation protein products and glycation end products in subjects exposed to low-dose benzene

Simple aromatic hydrocarbon benzene occurs naturally in crude oil and petroleum. Benzene has been internationally recognised as a haematotoxin and carcinogen. The involvement of oxidative stress is a major susceptibility factors for benzene hematotoxicity in humans. Advanced oxidation protein products (AOPPs) and advanced glycation end products (AGEs) are modified structures which can serve as markers of oxidative stress. The aim of this study is to assess modification of circulating AOPPs and AGEs, as early markers of oxidative stress, in subjects exposed to low dose of benzene. Furthermore the genetic polymorphism of glutathione-S-transferase (GST) may be related to health effects of benzene exposure, in fact both genotype T1 (GSTT1) and M1 (GSTM1) are involved in the detoxification of benzene oxide. The study was performed on 54 workers oil refinery employees. A group of 32 healthy age-matched subjects was included as controls. The AOPPs serum levels in oil refinery employees were higher in a statistically significant way than those measured in controls, but there were no significant changes in serum AGE levels between both groups. However, GST polymorphisms had not influence on serum levels of both biomarkers, so demonstrating that production of circulating AGEs and AOPPs in benzene parity-exposed workers levels is not dependent by GST genotypes. We can conclude that, in this condition, AOPPs are more sensitive marker of low benzene exposure than AGEs.     

Degradation of nonylphenol in spiked soils and in soils treated with organic waste products

Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the accumulation and effects of nonylphenol (NP) in the soil ecosystem. We have thus studied the degradation of NP and possible uptake in agricultural plants in greenhouse pot experiments. Different waste products including anaerobic and aerobic sludge, compost, and pig manure were incorporated into a sandy soil. In addition, NP was used to spike soil to known concentrations. Rape (Brassica napus L. cv Hyola 401) was sown in the pots and harvested after 30 d. In order to investigate the influence of plant growth on the degradation, plant-free pots were established. The concentrations in the soil were between 13 and 534 ppb dry weight. No plant uptake was observed above the detection limit at 100 ppb dry weight. When NP was added as waste to the soil, plant growth significantly stimulated the degradation. In experiments with anaerobic and aerobic sludge, respectively, 13 and 8.3% of NP remained in the soil from pots planted with rape compared with 26 and 18% in soil without plant growth. When NP was added as a spike to soil, the degradation was more complete and plant growth did not influence the degradation. Percentages of 2.2 and 1.8 were still in the soil at harvest for planted and plant-free pots, respectively. The degradation of NP was more extensive in sludge-amended soil compared with compost.     

Leaching and aging decrease nickel toxicity to soil microbial processes in soils freshly spiked with nickel chloride

Nickel is a trace metal that exhibits pronounced long-term immobilization reactions in soil. It is unknown if the slowly decreasing solubility of Ni in soil on aging correlates with decreased toxicity to soil biota. Three uncontaminated soils (pH 4.5-7.6) were contaminated with NiCl2 and experimentally leached or incubated outdoors with free drainage for up to 15 months. Nickel toxicity was measured for three microbial processes (potential nitrification rate, glucose-induced respiration, and C mineralization of maize residue). Results for leached and aged samples were compared with results for these soils tested immediately after spiking. Experimental leaching increased Ni ED50s (Ni dose to inhibit process by 50%) with a median factor of 2.0, whereas Ni ED50s in soils aged 15 months were a factor 1 to 23 (median, 4.6) larger compared to freshly spiked soils. Changes in soil Ni toxicity on aging generally were largest in the soil with the highest pH, consistent with the largest relative decreases of soil solution Ni concentration or predicted Ni2+ activity. Soil solution Ni concentrations explained part, but not all, of the reduction in Ni toxicity. The predicted soil solution Ni2+ activity also did not fully explain the reduced toxicity, which was ascribed to the variable concentrations of ions competing with Ni2+ at biological membranes (e.g., H+, Mg2+, or Ca2+) among treatments. It is concluded that testing Ni toxicity to soil microbial processes immediately after spiking soils in the laboratory overestimates Ni toxicity compared to aged soils. Soil solution composition in freshly spiked soils clearly is different from that in leached or aged soils; therefore, soil spiked with metal salts should be leached before toxicity tests begin.     

Qualitative and quantitative comparison of the cytotoxic and apoptotic potential of phytosterol oxidation products with their corresponding cholesterol oxidation products

Phytosterols contain an unsaturated ring structure and therefore are susceptible to oxidation under certain conditions. Whilst the cytotoxicity of the analogous cholesterol oxidation products (COP) has been well documented, the biological effects of phytosterol oxidation products (POP) have not yet been fully ascertained. The objective of the present study was to examine the cytotoxicity of beta-sitosterol oxides and their corresponding COP in a human monocytic cell line (U937), a colonic adenocarcinoma cell line (CaCo-2) and a hepatoma liver cell line (HepG2). 7beta-Hydroxysitosterol, 7-ketositosterol, sitosterol-3beta,5alpha,6beta-triol and a sitosterol-5alpha,6alpha-epoxide-sitosterol-5beta,6beta-epoxide (6:1) mixture were found to be cytotoxic to all three cell lines employed; the mode of cell death was by apoptosis in the U937 cell line and necrosis in the CaCo-2 and HepG2 cells. 7beta-Hydroxysitosterol was the only beta-sitosterol oxide to cause depletion in glutathione, indicating that POP-induced apoptosis may not be dependent on the generation of an oxidative stress. A further objective of this study was to assess the ability of the antioxidants alpha-tocopherol, gamma-tocopherol and beta-carotene to modulate POP-induced cytotoxicity in U937 cells. Whilst alpha/gamma-tocopherol protected against 7beta-hydroxycholesterol-induced apoptosis, they did not confer protection against 7beta-hydroxysitosterol- or 7-ketositosterol-induced toxicity, indicating that perhaps COP provoke different apoptotic pathways than POP. beta-Carotene did not protect against COP- or POP-induced toxicity. In general, results indicate that POP have qualitatively similar toxic effects to COP. However, higher concentrations of POP are required to elicit comparable levels of toxicity.     

涉水产品中铬的石墨炉原子吸收法测定条件的探讨

目的：探讨石墨炉原子吸收光谱法测定涉水产品中铬的试验条件。方法：涉水产品经过前处理后，用石墨炉原子吸收光谱法测定其铬的含量并找出最佳试验条件。结果：最佳灰化温度1300℃、原子化温度2300℃。方法的线性范围0～8.0μg/L，相关系数r=0.9996。RSD为1．34％～3．19％，回收率为90．4％～108．9％。结论：在方法的最佳试验条件下测定涉水产品中的铬可以得到满意的结果。