A summary of environmental legislation targeting disposable diapers and review of related literature

In recent years state and local governments, as well as private citizens, have become very concerned about the mounting solid waste disposal problem facing our nation. Special concern has been expressed over the presence of disposable diapers in the solid waste stream. Responding to the concerns, legislators in at least 25 states proposed actions regarding disposable diapers between 1990 and 1992. Several factors contributed to the number of legislative proposals regarding disposable diapers over the past few years. First was the public's and legislators' misconception about the contribution of disposable diapers to the solid waste stream. Second was an erroneous assumption held by the public and some legislators that biodegradation readily occurs in landfills. Third was the desire to increase demand for agricultural products by requiring the use of degradable products. These contributing factors and other issues surrounding the proposal and passage of environmental legislation pertaining to disposable diapers are presented in this paper and the relevant literature is summarized. To provide the necessary context, the paper contains a review of the literature concerning disposable diapers, their composition and usage; and their environmental impact and fate and a comparison of their performance and cost to those of cloth diapers.     

Latitudinal variation in the Dungeness crab,Cancer magister: zoeal morphology explained by incubation temperature

The difference in morphology between zoeae of Cancer magister Dana from Alaskan and Californian waters was documented to determine if the morphological variation is attributable to environmental influences. First-stage zoeae from Alaska have significantly longer carapace spines than zoeae from central California. The dorsal, rostral and lateral carapace spines were 14, 14 and 29% longer, respectively, in the Alaskan zoeae. The effect of temperature was tested on zoeal morphology as it is an obvious environmental difference between Alaskan and Californian waters. Ovigerous female crabs collected in southeastern Alaska in 1984 were held at 1°, 5°, 10° and 15° C until hatching occurred. Eggs were sampled seven times during the incubation period, and relative mortality, egg diameter and development stage were measured. All of the crabs and eggs at 1° C died before hatching occurred. Egg mortality averaged less than 2% in the other temperature treatments. Egg diameter increased significantly over the incubation period for all temperatures. Developmental rate of the embryos was inversely related to temperature. Hatching first occurred in 42 d at 15° C, 60 at 10° C and 160 d at 5° C. Newly hatched zoeae were collected and body length, dorsal, rostral and lateral carapace spines were measured. Significant differences existed between all temperatures for all spine lengths, with longer spines occurring at lower temperatures. Zoeal body lengths were also significantly different between the three temperatures. The results of this study question the use of spine lengths to distinguish similar larval species.     

Building a better methane generation model: Validating models with methane recovery rates from 35 Canadian landfills

The German EPER, TNO, Belgium, LandGEM, and Scholl Canyon models for estimating methane production were compared to methane recovery rates for 35 Canadian landfills, assuming that 20% of emissions were not recovered. Two different fractions of degradable organic carbon (DOC_f) were applied in all models. Most models performed better when the DOC_f was 0.5 compared to 0.77. The Belgium, Scholl Canyon, and LandGEM version 2.01 models produced the best results of the existing models with respective mean absolute errors compared to methane generation rates (recovery rates + 20%) of 91%, 71%, and 89% at 0.50 DOC_f and 171%, 115%, and 81% at 0.77 DOC_f. The Scholl Canyon model typically overestimated methane recovery rates and the LandGEM version 2.01 model, which modifies the Scholl Canyon model by dividing waste by 10, consistently underestimated methane recovery rates; this comparison suggested that modifying the divisor for waste in the Scholl Canyon model between one and ten could improve its accuracy. At 0.50 DOC_f and 0.77 DOC_f the modified model had the lowest absolute mean error when divided by 1.5 yielding 63 ± 45% and 2.3 yielding 57 ± 47%, respectively. These modified models reduced error and variability substantially and both have a strong correlation of r = 0.92.     

Concentrations of cyclic volatile methylsiloxanes in biosolid amended soil,influent, effluent,receiving water,and sediment of wastewater treatment plants in Canada

A comprehensive surveillance program was conducted to determine the occurrence of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in environmental compartments impacted by wastewater effluent discharges. Eleven wastewater treatment plants (WWTPs), representative of those found in Southern Ontario and Southern Quebec, Canada, were investigated to determine levels of cVMS in their influents and effluents. In addition, receiving water and sediment impacted by WWTP effluents, and biosolid-amended soil from agricultural fields were also analyzed for a preliminary evaluation of the environmental exposure of cVMS in media impacted by wastewater effluent and solids. A newly-developed large volume injection (septumless head adapter and cooled injection system) gas chromatography – mass spectrometry method was used to avoid contamination originating from instrumental analysis. Concentrations of D4, D5, and D6 in influents to the 11 WWTPs were in the range 0.282–6.69 μg L⁻¹, 7.75–135 μg L⁻¹, and 1.53–26.9 μg L⁻¹, respectively. In general, wastewater treatment showed cVMS removal rates of greater than 92%, regardless of treatment type. The D4, D5, and D6 concentration ranges in effluent were <0.009–0.045 μg L⁻¹, <0.027–1.56 μg L⁻¹, and <0.022–0.093 μg L⁻¹, respectively. The concentrations in receiving water influenced by effluent, were lower compared to those in effluent in most cases, with the ranges <0.009–0.023 μg L⁻¹, <0.027–1.48 μg L⁻¹, and <0.022–0.151 μg L⁻¹ for D4, D5, and D6, respectively. Sediment concentrations ranged from <0.003–0.049 μg g⁻¹ dw, 0.011–5.84 μg g⁻¹ dw, and 0.004–0.371 μg g⁻¹ dw for D4, D5, and D6, respectively. The concentrations in biosolid-amended soil, having values of <0.008–0.017 μg g⁻¹ dw, <0.007–0.221 μg g⁻¹ dw, and <0.009–0.711 μg g⁻¹ dw for D4, D5, and D6, respectively, were lower than those in sediment impacted by wastewater effluent in most cases. In comparison with the no-observed-effected concentrations (NOEC) and IC50 (concentration that causes 50% inhibition of the response) values, the potential risks to aquatic, sediment-dwelling, and terrestrial organisms from these reported concentrations are low.     

Dissociation of Sulfur Hexafluoride Tracer Gas in the Presence of an Indoor Combustion Source

ABSTRACT

As an odorless, nontoxic, and inert compound, sulfur hexafluoride (SF₆) is one of the most widely used tracer gases in indoor air quality studies in both controlled and uncontrolled environments. This compound may be subject to reactions with water vapor under elevated temperature to form acidic inorganic compounds such as HF and H₂SO₄. Thus, in the presence of unvented combustion sources such as kerosene heaters, natural gas heaters, gas log fireplaces, candles, and lamps, the SF₆ dissociation may interfere with measurements of the emissions from these sources. Tests were conducted in a research house with a vent-free natural gas heater to investigate these potential interferences. It was observed that the heater operation caused about a 5% reduction of SF₆ concentration, which can be an error source for the ventilation rate measurement and consequently the estimated pollutant emission rates. Further analysis indicates that this error can be much greater than the observed 5% under certain test conditions because it is a function of the ventilation flow rate. Reducing the tracer gas concentration has no effect on this error. A simple theoretical model is proposed to estimate the magnitude of this error.

The second type of interference comes from the primary and secondary products of the SF₆ dissociation, mainly H₂SO₄, SO₂, HF, and fine particulate matter (PM). In the presence of ~5 ppm SF₆, the total airborne concentrations of these species increased by a factor of 4-10. The tests were performed at relatively high SF₆ concentrations, which is necessary to determine the interferences quantitatively. The second type of interference can be significantly reduced if the SF₆ concentration is kept at a low ppb level.     

Policy options to reduce consumer waste to zero: comparing product stewardship and extended producer responsibility for refrigerator waste.

Today, over-consumption, pollution and resource depletion threaten sustainability. Waste management policies frequently fail to reduce consumption, prevent pollution, conserve resources and foster sustainable products. However, waste policies are changing to focus on lifecycle impacts of products from the cradle to the grave by extending the responsibilities of stakeholders to post-consumer management. Product stewardship and extended producer responsibility are two policies in use, with radically different results when compared for one consumer product, refrigerators. North America has enacted product stewardship policies that fail to require producers to take physical or financial responsibility for recycling or for environmentally sound disposal, so that releases of ozone depleting substances routinely occur, which contribute to the expanding the ozone hole. Conversely, Europe's Waste Electrical and Electronic Equipment (WEEE) Directive requires extended producer responsibility, whereby producers collect and manage their own post-consumer waste products. WEEE has resulted in high recycling rates of greater than 85%, reduced emissions of ozone-depleting substances and other toxins, greener production methods, such as replacing greenhouse gas refrigerants with environmentally friendly hydrocarbons and more reuse of refrigerators in the EU in comparison with North America.     

Manganese toxicity in Drosophila melanogaster: extension of the life span by resveratrol

The effect of resveratrol was studied on the life span and motor activity of Drosophila melanogaster treated with manganese (Mn). Two days after emerging from the pupa, male wild type D. melanogaster were fed for 13 days with corn media containing 15?mM Mn. Thereafter, Drosophila were divided into six groups of 300 flies each: (1) the flies remained treated with Mn; (2) began treatment with 0.43?mM resveratrol (Mn-resveratrol group); (3) received no additional treatment (Mn-no treatment group); (4) simultaneously fed with Mn and resveratrol (Mn?+?resveratrol group). In addition, a control (5) with no treatment and another group (6) fed only with resveratrol after emerging from the pupa were included. All Mn-treated flies (group 1) were dead on the 25th day. The life span in the resveratrol group was 91?±?0.33 days (mean?±?S.E.M.) and in Mn-resveratrol flies was 83?±?2 days. These two values were significantly higher than those detected in the control (5) and Mn-no treatment (group 3) flies whose life span were 68?±?0.33 and 67?±?2.31 days, respectively. The Mn?+?resveratrol-fed flies had a markedly higher life span (31?±?1.53 days) than Mn-fed flies (23?±?0.88 days). In the flies that received Mn (Mn and Mn?+?resveratrol groups), the motor activity decreased significantly with respect to control (groups 5) and the Mn–resveratrol and resveratrol groups. In conclusion, resveratrol increased significantly the life span of Mn-treated D. melanogaster.