Effect of aflatoxin B1, ochratoxin and rubratoxin B on a protozoan,Tetrahymena pyriformis HSM

Summary Rubratoxin B is more inhibitory to the growth ofT. pyriformis than is either aflatoxin B₁ or ochratoxin. Only a marginal effect on cell respiration was exerted by these mycotoxins. The presence of the divalent ions, Mg⁺⁺, Ca⁺⁺ and Fe⁺⁺, did not reduce the toxicity of rubratoxin B. A bioassay sensitive to 1 to 5 g/ml rubratoxin B has been developed employingT. pyriformis.     

Determination of nickel in lung specimens of thirty-nine autopsied nickel workers

Summary Lung specimens from 39 nickel refinery workers autopsied during the period from 1978 to 1984 were analyzed for nickel. Fifteen of the workers were employed in the Roasting and Smelting Department, where exposure to nickel was predominantly in the form of nickel-copper oxides, Ni₃S₂ and metallic dust. The remaining 24 men worked in the Electrolysis Department. Exposure in this group was considered to be mostly to the water-soluble compounds, NiSO₄ and NiCl₂, but also to a lesser degree to water-insoluble nickel compounds such as nickel-copper oxides and sulphides. The arithmetic mean ± SD for nickel concentration in lung tissues expressed in gg^–1 dry wt for the 39 workers was 150 ± 280. In the workers employed in the Roasting and Smelting Department, the average nickel concentration was 330 ± 380; for those who worked in the Electrolysis Department it was 34 ± 48. Lung tissue from 16 autopsied persons not connected with the refinery had an average nickel concentration of 0.76 ± 0.39. Statistical analysis based on log-normal distributions of the measured nickel concentrations allowed three major conclusions to be formulated: (1) nickel refinery workers exhibit elevated nickel levels in lung tissues at autopsy; (2) workers of the Electrolysis Department and the Roasting Smelting Department constitute distinct groups with respect to the accumulation of nickel in lung tissue; (3) workers who were diagnosed to have lung cancer had the same lung nickel concentrations at autopsy as those who died of other causes.     

Mercury and Methylmercury Accumulation and Excretion in Prairie Voles (<Emphasis Type="Italic">Microtus ochrogaster</Emphasis>) Receiving Chronic Doses of Methylmercury

Methylmercury cation (MeHg) and divalent mercury (Hg⁺⁺) accumulation in liver, kidney, and brain were quantified in prairie voles (Microtus ochrogaster) at 0, 3, 6, and 12 weeks during chronic exposure to aqueous MeHg. Dose groups received deionized water or aqueous solutions containing 9, 103, or 920 ng MeHg/ml. Our study presents temporal patterns of Hg⁺⁺ and MeHg concentrations in organ tissues and makes inter-tissue comparisons at each time point to illustrate the accumulation and distribution of Hg species during the study. MeHg was accumulated in tissues for 3 weeks and then concentrations plateaued. Mercury accumulated in brain, liver, and kidney to average concentrations of 510 ng/g, 180 ng/g, and 3400 ng/g, respectively. MeHg and Hg⁺⁺ concentrations were roughly equivalent in liver, kidney, and urine. MeHg concentrations in brain tissue were 2 to 20 times the concentrations of Hg⁺⁺. Regression analysis was also used to demonstrate the utility of urinalysis as an indicator of Hg⁺⁺ and MeHg concentrations in organ tissue (p < 0.001).     

Effects of sodium nitrate aerosol on cardiopulmonary function of dogs, sheep, and man

Submicronic aerosols of nitrate salts are synthesized in the atmosphere through further oxidation of nitrogen oxides produced during the burning of fossil fuels. This study was conducted to determine whether brief exposure to submicronic aerosol of sodium nitrate in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs breathing up to 10 mg/m³ of sodium nitrate (NaNO₃) aerosol for 7.5 min showed no significant alterations in respiratory resistance, static lung compliance, and functional residual capacity. A 4-hr exposure to NaNO₃ aerosol (5 mg/m³) produced neither significant changes in lung mechanics, functional residual capacity, pulmonary and systemic arterial pressures, cardiac output, heart rate, and arterial blood gases in anesthetized dogs nor a change in tracheal mucous velocity in conscious sheep. Both normal and asthmatic adults who breathed submicronic aerosol of NaNO₃ (up to 1 mg/m³) for 10 min showed no significant changes in lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, and oscillation mechanics of the chest-lung system. NaNO₃ aerosol (1000 μg/m³ for 10 min did not significantly change pulmonary capillary blood flow, diffusing capacity, oxygen consumption, and pulmonary tissue volume as measured by a rebreathing technique. Thus, brief exposure to high concentrations of submicronic aerosol of sodium nitrate does not produce immediate adverse effects on cardiopulmonary function of anesthetized dogs, conscious sheep, and normal and asthmatic adults.     

Induction of Oxidative Stress in the Red Macroalga <Emphasis Type="Italic">Gracilaria tenuistipitata</Emphasis> by Pollutant Metals

Heavy metals are environmental pollutants that have the potential to induce severe stress-reactions in organisms on land as well as in the sea. We have studied effects of short term sublethal concentrations of copper (Cu²⁺) and cadmium (Cd²⁺) on the reactive oxygen metabolism of the marine red macroalga Gracilaria tenuistipitata. Additions of either 0.2 ppm Cu²⁺ or 1 ppm Cd²⁺ caused decreased growth (60%), increased oxidation of lipids and increased oxidative damage to proteins as shown by increased content of protein carbonyl groups. Together this strongly suggests an induction of oxidative stress. Cu²⁺ caused more oxidative damage than Cd²⁺. As a response to the increased oxidative stress, addition of Cu²⁺ induced the activities of catalase, ascorbate peroxidase, and superoxide dismutase. In contrast, Cd²⁺ only caused increased catalase activity. Ten-fold lower concentrations of the metals did not cause an increase in enzyme activity. Both heavy metals also increased the content of the antioxidants -carotene and lutein. The results show that Cd²⁺ and, to a larger extent, Cu²⁺ induce oxidative stress in short-term experiments and the seaweed responds by increasing the activity of the reactive oxygen metabolism.     

Binding of cadmium by cyanobacterial growth media: Free ion concentration as a toxicity index to the cyanobacteriumNostoc UAM 208

A quantitative study of cadmium binding to three different growth media for nitrogen-fixing cyanobacteria was done with the aid of a solid state ion-specific electrode. Kratz and Myers modified medium and Arnon medium bound large amounts of Cd²⁺, BG11₀ medium had less binding capacity. Of the media components, phosphate ion showed the greatest ability to bind Cd²⁺. Different pHs, the size of cell inoculum and two buffers (Tricine and HEPES, 25 mM) also changed the availability of free cadmium ion in solution.The effect of free Cd²⁺ ion towards the cyanobacteriumNostoc UAM 208, isolated from a heavy metal polluted environment, also was tested. The effective concentration affecting 50% of population (EC₅₀), at 120 h of exposure, was less for nitrogenase activity (0.26 g/mL) than for growth (0.55 g/mL), suggesting that this enzyme activity is more sensitive to cadmium than growth. Furthermore, cadmium toxicity was influenced by the addition of buffers to the growth medium. In the presence of buffer, Tricine (25 mM), growth and nitrogenase activity was reduced by 50% at a total cadmium concentration of about 115 g/mL, although no free ion was detected in this case.These results suggest that although generally cadmium toxicity is a function of free metal ion concentration, this can also vary in the presence of complexing agents.     

Cardiorespiratory and thermal effects of wearing gas protective clothing

Summary Six healthy men aged 25 to 37 walked on a treadmill at work levels of 21 and 41% of their for 25 to 30 min wearing gas protective clothing (GPC) consisting of an impermeable suit with a self-contained breathing apparatus (total weight 25 kg) or shorts (control tests, CT) in a temperate environment (t _a 24.3°C ± 1.0°C, rh 30–50%). When the GPC was worn at 21 and 41% , the most prominent increases, compared with the CT, were noted in the heart rate ( ± SE, 120 ± 5 vs 76 ± 3 beats min^–1 and 171 ± 5 vs 103 ± 3 beats min^–1), mean skin temperature (36.1 ± 0.2 vs 31.3° C ± 0.1°C and 36.9 ± 0.3 vs 30.9°C ± 0.4°C) and sweat rate (473 ± 51 vs 70 ± 23 g m^–2 h^–1 and 766 ± 81 vs 135 ± 18 g m^–2 h^–1) indicating a high cardiovascular and thermoregulatory strain, which was not decreased by ventilating the suit with an air flow of 281 min^–1 at 41% . The ventilation, oxygen consumption and production of carbon dioxide increased in relation to the extra weight of the GPC, partly dependent on the dynamic work level. It was concluded that the increase in the physiological load caused by the GPC was so high that the work-rest regimens, workers' level of physical fitness, cardiovascular health and heat tolerance should be considered whenever gas protective clothing is used.     

Regressors of whole-carcass zinc phosphide/phosphine residues in voles: Indirect evidence of low hazards to predators/scavengers

Whole-carcass residues of the rodenticide zinc phosphide (Zn₃P₂) and hydrolyzed phosphine (PH₃) were determined for voles (Microtus spp.) that died following ingestion of a 2% Zn₃P₂ steam rolled oat (SRO) groats bait. Procedures involved: a three-day acceptance test to assess vole consumption (n=27) of control SRO groats and several one-day Zn₃P₂- (n=13) or control-bait (n=4) tests to characterize onset of pharmacotoxic signs and to obtain fatally-dosed carcasses for residue analyses. Carcasses were stored in liquid nitrogen (LN₂) to maximize retention of Zn₃P₂/PH₃ residues prior to chemical determinations. Linear regressions were computed between pairs of consumption and residue variables. Main results were the following: (1) mean (±SD) consumption of control bait was 2.5 (±0.9), 3.0 (±0.9), and 2.8 (±0.8) g on days 1, 2, and 3, respectively (10.6 ± 4.6% of body weight); (2) all test-bait voles (n=13) died 4–12 h after bait presentation, with lethargy and respiratory distress key signs of toxicosis; (3) whole-carcass Zn₃P₂ residues averaged 1.73 mg (minmax: 0.31–4.95), and PH₃ residues averaged 10.6 g (minmax: 0.5–21.0); and (4) significant linear regressions were found between bait consumption/Zn₃P₂ intake and body weight (r²=0.64, p0.001), carcass Zn₃P₂ and bait consumption/Zn₃P₂ intake (r²=0.32, p0.043), and carcass Zn₃P₂ and body weight (r²=0.60, p0.002). Certain analytical and hazards issues are discussed.     

Safety of the etonogestrel-releasing implant during the immediate postpartum period: a pilot study

Background

The effects of etonogestrel (ETG)-releasing contraceptive implant during the immediate postpartum period on maternal safety are unknown.

Study design

Forty healthy women exclusively breastfeeding were randomized to receive either ETG-releasing implant 24–48 h after delivery (n=20) or depot medroxyprogesterone acetate (DMPA group; n=20) at the sixth week postpartum. We measured blood pressure, maternal and neonatal weight, body mass index (BMI; kg/m²), waist circumference (WC), complete blood count, C-reactive protein, interleukin-6, tumor necrosis factor (TNF-alpha), lipid profile, fasting serum glucose and maintenance of exclusive lactation up to the 12th week postpartum.

Results

Decreases in mean maternal weight, BMI (kg/m²) and WC were significantly greater in the ETG-releasing implant group than in the DMPA group during the first 6 weeks postpartum (-4.64±2.71 kg vs. -2.6±2.45 kg mean±SD, p=.017; -1.77±1.06 kg/m² vs. -0.97±0.95 kg/m², p=.026; -15.3±6.72 cm vs. -9.05±5.84 cm, p=.003, respectively). In addition, total cholesterol and HDL, were lower in DMPA users, and TNF-alpha and leukocytes were higher in DMPA users compared to in the implant group, between 6 and 12 weeks after delivery. The newborns of implant users showed a trend towards gaining more weight, as compared with the infants of the DMPA mothers during the first 6 weeks of life (implant group: +1460.50±621.34 g vs. DMPA group: +1035.0±562.43 g, p=.05). The remaining variables, including the duration of exclusive breastfeeding, were similar between the groups.

Conclusion

The insertion of ETG-releasing contraceptive implant during the immediate postpartum period was not associated with deleterious maternal clinical effects or with significant maternal metabolic alterations or decreased infant weight gain.     

Factors controlling the lung dose of road traffic-generated sub-micrometre aerosols from outdoor to indoor environments

Estimates of lung dose of submicron particles in the human respiratory system play an essential role in assessing health outcomes of aerosol exposure. The objectives of this study are to calculate the regional lung dose of traffic-generated particles by different metrics from exposure in outdoor and indoor environments and to identify main factors determining the lung dose. Particle number size distributions were collected in both indoor and outdoor environments in two unoccupied apartments from 22nd February to 30th April 2012 in Bologna, Italy. The whole lung doses of outdoor aerosols by number, surface area and mass at a traffic site were 1.0?×?10¹⁰ particles/h, 130 mm²/h and 1.9 μg/h, respectively. A majority of particles by number and surface area were found to deposit in the alveolar region (65%). The physical properties of particles such as shape, hygroscopicity and density play an important role in the calculation of surface area and mass dose due to shifting of the lung deposition curve. Particle number can predict well the regional dose by number, while PM_2.5 and PM₁₀ are good metrics for the prediction of surface area and mass dose. Good correlations between NO_x and the surface areas and mass dose (r²?~?0.8) and number dose (r²?~?0.7) of submicron aerosols suggest that NO_x may be a good indicator for predicting the health outcomes of traffic-generated aerosols. The doses of indoor sub-micrometre aerosols are less than those of outdoor aerosols by factors of 4.1 (for number), 2.7 (for surface area) and 2.1 (for mass). Due to traffic emissions, the lung dose of outdoor aerosols in the traffic area was much higher than that in the residential area by 5 times for number and surface area and 2 times for mass. A different exercise level (standing, walking, running and cycling) has only a slight influence on the whole lung deposition fraction of submicron aerosols but has a large effect on the dose due to differences in ventilation rate.     

The effect of milk fermented by yogurt cultures plus <Emphasis Type="Italic">Lactobacillus casei</Emphasis> DN-114001 on the immune response of subjects under academic examination stress

Summary Background A suppressed immune response has been documented in students under examination stress. Aims The current study aimed to evaluate the effect of milk fermented with yogurt cultures plus Lactobacillus casei DN-114001 (Actimel^®) on the immune system of subjects under academic examination stress. Methods University students were allocated to one of two groups, receiving during 6 weeks (3 weeks prior to, as well as the 3-week duration of the examination period) either: a) a glass of semi-skimmed milk each day (control group, n=63) or b) two 100mL portions per day of fermented milk (treatment group, n=73). Anxiety and immunological measurements were monitored at baseline (Phase 0) and study end (Phase 1). Results The results were expressed as the differences between the data obtained from Phase 0 and Phase 1. This was calculated by subtracting Phase 1 results from the Phase 0 and it is denominated Treatment effect. Mean (± SE) anxiety increased significantly (P<0.05) over the 6-week study in all students, from 40.74±2.50 to 61.19±2.64 (in percentiles). There was no significant treatment effect since this increase was similar in the control and the treatment groups (21.65±5.09 vs 19.14±3.67, respectively). However, there was a significant treatment effect (P<0.05) on the mean change in absolute number of lymphocytes during the 6-week study, which decreased in the control group (–0.04±0.12 cells x 103/mm³) and increased in the treatment group (0.37±0.11 cells x 103/mm³). There was also a significant treatment effect (P<0.05) on the change in absolute numbers of CD56 cells during the 6-week study. Mean absolute CD56 cells significantly decreased (P<0.05) in the control group (–51.97±21.33 cells/mm³),while remaining similar in the treatment group (17.29±17.27 cells/mm³). During the study, mean serum cortisol increased 4.30±0.98 µg/dL in the control group, and 1.75±1.05 µg/dL in the treatment group and no significant differences were found between both values (P=0.062). Conclusions Milk fermented with yogurt cultures plus Lactobacillus casei DN-114001 was able to modulate the number of lymphocytes and CD56 cells in subjects under academic examination stress.     

Dislodgeability of pesticides from products made with recycled pesticide container plastics

Products containing high density polyethylene plastic from recycled pesticide containers were tested for levels of dislodgeable pesticide under dry and damp conditions. Trifluralin was found to be the pesticide released in largest quantity from plastic curbstops. Levels dislodged ranged from 0.18 g/100 cm² to 4.18 g/100 cm² for all plastics tested. Significantly higher dislodgeability occurred from products where low density polyethylene plastics were used to dilute pesticide container plastics, compared to products containing only pesticide container plastics. Amounts of trifluralin dislodged by wiping with dry cheesecloth for 15 min were 0.83±0.50, 3.52±0.40, and 2.53±0.56 g/100 cm² for products containing 100%, 50%, and 25% pesticide container plastics, respectively. Respective levels of trifluralin dislodged with saline-dampened cheesecloth were 2.00±0.71, 3.21±0.82, and 1.16±0.51 g/100 cm². Decreased amounts of trifluralin were released after product weathering, with levels dislodged under dry conditions of 0.007±0.002, 0.0083±0.001 and 0.0089±0.001 m/100 cm², respectively. Similar studies of asphalt products containing recycled pesticide containers found the average amounts of trifluralin and 2,4-D iso-octyl ester dislodged were 0.33 g/100 cm² and 1.35 g/100 cm², respectively. Pesticide levels dislodged from all products tested were within acceptable daily intake levels. Calculations of margins of safety showed exposure to products made with recycled containers would not present an unacceptable risk to individuals coming in contact with them.     

Estimating Regional Spatial and Temporal Variability of PM2.5 Concentrations Using Satellite Data,Meteorology, and Land Use Information

Background

Studies of chronic health effects due to exposures to particulate matter with aerodynamic diameters ≤ 2.5 μm (PM_2.5) are often limited by sparse measurements. Satellite aerosol remote sensing data may be used to extend PM_2.5 ground networks to cover a much larger area.

Objectives

In this study we examined the benefits of using aerosol optical depth (AOD) retrieved by the Geostationary Operational Environmental Satellite (GOES) in conjunction with land use and meteorologic information to estimate ground-level PM_2.5 concentrations.

Methods

We developed a two-stage generalized additive model (GAM) for U.S. Environmental Protection Agency PM_2.5 concentrations in a domain centered in Massachusetts. The AOD model represents conditions when AOD retrieval is successful; the non-AOD model represents conditions when AOD is missing in the domain.

Results

The AOD model has a higher predicting power judged by adjusted R² (0.79) than does the non-AOD model (0.48). The predicted PM_2.5 concentrations by the AOD model are, on average, 0.8–0.9 μg/m³ higher than the non-AOD model predictions, with a more smooth spatial distribution, higher concentrations in rural areas, and the highest concentrations in areas other than major urban centers. Although AOD is a highly significant predictor of PM_2.5, meteorologic parameters are major contributors to the better performance of the AOD model.

Conclusions

GOES aerosol/smoke product (GASP) AOD is able to summarize a set of weather and land use conditions that stratify PM_2.5 concentrations into two different spatial patterns. Even if land use regression models do not include AOD as a predictor variable, two separate models should be fitted to account for different PM_2.5 spatial patterns related to AOD availability.     

Anti-oxidative Responses on Hepatic Tissue of Zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) in a Short Duration of Sub-lethal Concentrations of Cadmium Exposure

The aim of the present study was to identify whether the responses of oxidative stress in zebrafish liver are similar to those in mammalians upon low doses of Cd²⁺ exposure in short durations. Fish were exposed to 1.78 μM Cd²⁺ (treatment) and 0.0 μM Cd²⁺ (control) for 0, 1, 3, and 6 h. The reactive oxygen species (ROS) and lipid peroxidation (LPO) of hepatic tissues significantly increased after 3 and 6 h of Cd²⁺ exposure, respectively. Antioxidants glutathione peroxidase (gpx1a), superoxide dismutase (sod), and catalase (cat) were up regulated after 1–3 h, and metallothionein isoforms (smtB and mt2) increased after 3–6 h of Cd²⁺ exposure. The caspase-3 and p53 mRNA expressions significantly increased threefolds after 1 h of Cd²⁺ exposure. Results confirmed that oxidative stress in the hepatic tissue was induced by Cd²⁺ within 3 h. However, anti-oxidative functions immediately up regulated, causing cell apoptosis levels to decrease after 6 h of Cd²⁺ exposure.     

Effects on ionic composition of blood and tissues ofAnodonta grandis grandis (Bivalvia) of an addition of aluminum and acid to a lake

To test the hypothesis that summer low pH, episodic events cause stress and mortality in aquatic organisms including mussels, alum (aluminum sulfate) was added near the point of inflow to Lake 114 in the Experimental Lakes Area, northwestern Ontario from 3 to 5 July 1984. Lake 114 was at pH 5.9 before the alum addition. The alum produced measured extremes of pH 4.5 and [Al] of 2,237 g/L near the point of addition. This study examined the effects of the alum addition on ionic concentrations of blood and tissue (gills, adductor muscle, foot and visceral mass) of the floater mussel,Anodonta grandis grandis. Mussels were collected from a second lake, 377, and introduced into Lake 114 at five locations five days before the alum addition. In response to transfer from the oligotrophic, unmanipulated Lake 377 to acidified Lake 114 (pH 5.9), blood of mussels showed a marked elevation of [Ca⁺⁺], decline in [Mg⁺⁺] and a temporary increase in [Cl^–] but no change in [Na⁺], [K⁺] or [SO₄ ⁼]. During the alum addition, in mussels near the point source of the alum addition, blood [Na⁺] and [Cl^–] declined and [Ca⁺⁺] became still more elevated. Mussels suffered no mortality associated with the alum addition and almost no mortality during 26 days in Lake 114. Gill increased in [Al], [Ca], [Mn], declined in [Na] and showed no change in [Cd] in mussels near the alum addition. Visceral mass and adductor muscle also had lower [Na] in mussels near the point of alum addition. We attribute the increase in blood [Ca⁺⁺] to the dissolution of the Ca stores in the shell and/or mantle of mussels. This would provide protection to the mussels during short-term declines in pH such as spring or summer episodic events. Never-theless, chronic exposure to small decreases in pH by mussels, already near the limits for obtaining sufficient Ca⁺⁺, might be intolerable. It follows that acidification to the pH of 5.9 of soft water lakes containing mussels would be expected to lead to the loss of A.g. grandis from these waters.     

Global Estimates of Ambient Fine Particulate Matter Concentrations from Satellite-Based Aerosol Optical Depth: Development and Application

Background

Epidemiologic and health impact studies of fine particulate matter with diameter < 2.5 μm (PM_2.5) are limited by the lack of monitoring data, especially in developing countries. Satellite observations offer valuable global information about PM_2.5 concentrations.

Objective

In this study, we developed a technique for estimating surface PM_2.5 concentrations from satellite observations.

Methods

We mapped global ground-level PM_2.5 concentrations using total column aerosol optical depth (AOD) from the MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multiangle Imaging Spectroradiometer) satellite instruments and coincident aerosol vertical profiles from the GEOS-Chem global chemical transport model.

Results

We determined that global estimates of long-term average (1 January 2001 to 31 December 2006) PM_2.5 concentrations at approximately 10 km × 10 km resolution indicate a global population-weighted geometric mean PM_2.5 concentration of 20 μg/m³. The World Health Organization Air Quality PM_2.5 Interim Target-1 (35 μg/m³ annual average) is exceeded over central and eastern Asia for 38% and for 50% of the population, respectively. Annual mean PM_2.5 concentrations exceed 80 μg/m³ over eastern China. Our evaluation of the satellite-derived estimate with ground-based in situ measurements indicates significant spatial agreement with North American measurements (r = 0.77; slope = 1.07; n = 1057) and with noncoincident measurements elsewhere (r = 0.83; slope = 0.86; n = 244). The 1 SD of uncertainty in the satellite-derived PM_2.5 is 25%, which is inferred from the AOD retrieval and from aerosol vertical profile errors and sampling. The global population-weighted mean uncertainty is 6.7 μg/m³.

Conclusions

Satellite-derived total-column AOD, when combined with a chemical transport model, provides estimates of global long-term average PM_2.5 concentrations.     

Selenium uptake and transfer in an aquatic food chain and its effects on fathead minnow larvae

The transfer of Se (Na₂SeO₄) was followed through a laboratory food chain (wateralgae-rotifer-larval fish) and its effect on larval fathead minnows (Pimephales promelas). Selenium transfer between algae (Chlorella pyrenoidosa) and rotifers (Brachionus calyciflorus) was a function of time and food availability. Selenium concentrations in the rotifers ranged from 46 to 91g Se · g^–1 dry weight after 5 hr of feeding. Selenium concentrations (±SD) in larval fish reached 61.1±1.1 g Se · g^–1 dry weight for 9 day-old larvae and 51.7+1.6 g Se · g^–1 for 17 day-old larvae after 7 and 9 days of feeding with Se-contaminated rotifers, respectively. Final dry weights of larvae fed Se-contaminated rotifers were significantly lower than those of controls, although acute toxicity (mortality) was not demonstrated. The biological halflife of food-derived Se in the larvae was 28 days.Based on a thesis by William N. Bennett submitted in partial fulfillment for the degree of Master of Science in Zoology at the University of Wisconsin-Milwaukee.     

Oxygen and glucose consumption and lactate production of erythrocytes of workers exposed to inorganic lea

Summary Oxygen and glucose consumption and lactate production were measured at 37° C in samples of buffered suspensions of red cells from 39 subjects exposed occupationally to inorganic lead and from 24 non-exposed subjects. The same measurements were made in samples of red cells from normal blood and from suspensions or normal erythrocytes in saline, which had been incubated for 1 h at 37° C with varying amounts of added lead chloride. The haemoglobin concentration, the reticulocyte count, the stippled erythrocyte count, the concentration of coproporphyrin in urine, and the concentration of lead in blood were also determined in the workers exposed to lead.These conventional criteria indicated that the subjects were fairly heavily exposed, with some individuals in a state of mild poisoning. The washed erythrocytes from the exposed subjects, suspended in phosphate buffer, consumed more glucose during 3 h of observation (2.5 ± 0.4 M/ml (packed) cells·h[ =mean ± s. d.]) than did those from the non-exposed controls (2.2 ± 0.3 M/ml cells·h); the difference of the means was statistically highly significant (t = 3.88; p<0.001). The mean lactate production in samples of cells of the exposed workers (4.1 ± 0.5 M/ml cells·h) was slightly higher than in those of the controls (3.8 ± 0.7 M/ml cells·h), but the difference was not statistically significant. There was a statistically significant difference between the mean glycolytic quotients in the cells of the exposed people (0.85 ± 0.13) and those of the non-exposed controls (0.93 ± The oxygen consumption was identical within the experimental error in samples of both groups of subjects.There was a significant correlation between the glucose consumption in samples of erythrocytes of exposed subjects and the coproporphyrin concentration in urine of their respective donors. The findings are interpreted as likely to result from a shift towards a younger mean in the age distribution of the erythrocyte populations in samples of exposed workers as compared to those of non-exposed normal subjects, but other possible interpretations are also suggested. We conclude that (a) the previously reported deficiency in the potassium exchange of red cells from people exposed to inorganic lead is probably not due to a decreased rate of metabolic energy release in the cells; and that (b) the functional disturbance measured here in the red cells of the exposed people may reflect fairly well the overall effect of absorbed lead in the individuals' organisms.Final concentrations of 5 × 10^–9–5 × 10^–8M of lead chloride added in vitro into samples of whole blood or erythrocytes suspended in saline, which were incubated for I h at 37° C, did not affect the oxygen or glucose consumption nor the lactate production of the subsequently washed red cells resuspended in phosphate buffer at 37° C.Mrs S. Asp, M. A., drew the figures and performed the statistical calculations and Miss T. Lönnberg gave skilful technical assistance.Part of the material in this paper has been accepted for presentation at the XV International Congress of Occupational Health, Vienna, September 1966.The present work has been sponsored by a research grant from the Helena Lundqvist foundation to S. H.     

Cadmium kinetics in freshwater clams. III. Effects of zinc on uptake and distribution of cadmium inAnodonta cygnea

Freshwater clams (Anodonta cygnea) were exposed to Cd²⁺ (25 g/L) or to Cd²⁺ (25 g/L) plus Zn²⁺ (2.5 mg/L). In the presence of zinc, uptake of cadmium in whole clam was halved. In organs such as the gills, mantle, and labial palps a still larger reduction of Cd accumulation occurred. By contrast, accumulation in midgut gland and kidney was hardly affected by the presence of zinc. It is shown that in the gills zinc competes with cadmium for metal binding sites both within the particulate fraction and the high-molecular weight fraction of the cytosol. Zinc probably did not induce an enlarged synthesis of specific metal-binding, metallothionein-like, proteins. In conclusion, zinc exerts antagonistic effects on uptake of cadmium by gills, and accelerates Cd transport from the gills towards the internal organs.