Pesticide risk assessment: A study on inhalation and dermal exposure to 2,4-D and paraquat among Malaysian paddy farmers

A cross-section analytical study was conducted to evaluate the risk of pesticide exposure to those applying the Class II pesticides 2,4-D and paraquat in the paddy-growing areas of Kerian, Perak, Malaysia. It investigated the influence of weather on exposure as well as documented health problems commonly related to pesticide exposure. Potential inhalation and dermal exposure for 140 paddy farmers (handlers of pesticides) were assessed. Results showed that while temperature and humidity affected exposure, windspeed had the strongest impact on pesticide exposure via inhalation. However, the degree of exposure to both herbicides via inhalation was below the permissible exposure limits set by United States National Institute of Occupational Safety and Health (NIOSH). Dermal Exposure Assessment Method (DREAM) readings showed that dermal exposure with manual spraying ranged from moderate to high. With motorized sprayers, however, the level of dermal exposure ranged from low to moderate. Dermal exposure was significantly negatively correlated with the usage of protective clothing. Various types of deleterious health effects were detected among users of manual knapsack sprayers. Long-term spraying activities were positively correlated with increasing levels of the gamma-glutamyl transpeptidase (GGT) liver enzyme. The type of spraying equipment, usage of proper protective clothing and adherence to correct spraying practices were found to be the most important factors influencing the degree of pesticide exposure among those applying pesticides.     

Matrix effects in analysis of dialkyl phosphate metabolites of organophosphate pesticides in urine by gas chromatography/tandem mass spectrometer

Urinary dialkyl phosphate metabolites (DAPs) are used as biomarkers to evaluate human exposure to organophosphate pesticides. The objective was to evaluate potential artifacts in urinary DAPs analysis during sample preparation and method calibration. Diluted urine pools were commonly used to prepare calibration standards to minimize the effects due to the complexity of urine matrix. Matrix effects on measurements of DAPs were evaluated by spiking known amount of standards into distilled water, synthetic urine and diluted urine pool. Different matrices resulted in similar concentrations detected for all target compounds, except dimethylphosphate (DMP) with the deviation of measurement as large as eight times the spiked amount. In this study, we also found that urinary particles, which usually appeared after thawing frozen human urine samples, could affect the measurements of DAPs, especially DMP and diethylthiophosphate (DETP). Results of DAPs measurements in three types of sample matrices, i.e. urine without particles, urine with particles and particles only were compared. DETP could be subject to large error during this preparation step. The use of deuterated and ¹³C₁₂-labeled DAPs as internal standards is also evaluated. Overall, these issues can cause misidentification and inaccuracies, which may significantly affect the data quality.     

Nutrient Export from Watersheds on Mt. Desert Island, Maine, as a Function of Land Use and Fire History

A study of 13 small (less than 7.5 km²) watersheds on Mt. Desert Island, Maine, was conducted from January 1999 to September 2000 to determine nutrient export delivery to coastal waters around the island, and to determine whether a series of wildfires in 1947 have affected nutrient export in burned watersheds. Nutrient export (nitrate–nitrogen, total nitrogen, total phosphorus) was determined for each watershed during the study period, and was normalized by watershed area. The yield of nitrate–nitrogen (N) ranged from 10 to 140 kg/km²/year. Total N yield ranged from 42 to 250 kg/km²/year. Total phosphorus (P) yield ranged from 1.4 to 7.9 kg/km²/year. Watersheds entirely within Acadia National Park (lacking human land-based nutrient sources) exported significantly less total N and total P than watersheds that were partly or entirely outside the park boundary. Nitrate–N export was not significantly different in these two groups of watersheds, perhaps because atmospheric deposition is a dominant source of nitrate in the study area. No relation was observed between burn history and nutrient export. Any effect of burn history may be masked by other landscape-level factors related to nutrient export.     

The Contribution of Acadia PRIMENet Research to Science and Resource Management in the National Park Service

Acadia National Park was one of the 14 sites included in the Park Research and Intensive Monitoring of Ecosystems network (PRIMENet). For eight years the EPA monitored ultraviolet (UV) radiation at this site, with the National Park Service (NPS) sponsoring a total climate and air monitoring station. Under the auspices of PRIMENet, research projects were initiated that investigated the effects of UV on amphibians, determined watershed mass balances, and developed a model of deposition along an elevational gradient. The monitoring data and research results have been used by park management to protect vegetation and water resources from ozone and deposition. These data are now being used to develop a “vital signs” monitoring program under the NPS’ Inventory and Monitoring Program. These data sets have been used in regional, national and international programs to protect human health and resources from air pollution. Public outreach has been accomplished through web site resources and via the Schoodic Education and Research Center.     

东江水库对耒水中下游原生动物的影响

为评价东江水库建成对耒水中下游水生生物的影响,１９９３年作者对东江水库坝下耒水中下游原生动物进行了两次调查。结果四个断面共发现原生动物８４种,其中丰水季（８月）５９种,多于枯水季（１０月底）的４６种,但丰水季数量（４３５个／Ｌ）和生物量（０．０３６ｍｇ／Ｌ）都低于枯水季（３．２４４个／Ｌ,０．３３５ｍｇ／Ｌ）;多样性指数与种种类数一样,多是丰水季大于枯水季。建库后,从中游到下游原生动物种类数,数量     

Modeling and risk assessment for soil temperatures beneath prescribed forest fires

Prescribed fire is a management tool used by wildland resource management organizations in many ecosystems to reduce hazardous fuels and to achieve a host of other objectives. To study the effects of fire in naturally accumulating fuel conditions, the ambient soil temperature is monitored beneath prescribed burns. In this study we developed a stochastic model for temperature profiles (values at 15 minute intervals) recorded at four depths beneath the soil during a large prescribed burn study. The model was used to assess the temporal fit of the data to particular solutions of the heat equation. We used a random effects model to assess the effects of observed site characteristics on maximum temperatures and to estimate risks of temperatures exceeding critical levels in future similar prescribed fires. Contour plots of estimated risks of temperatures exceeding 60°C for a range of fuel levels and soil depths indicated high risks of occurrence, especially when the moisture levels are low. However, the natural variability among sites seems to be large, even after controlling fuel and moisture levels, resulting in large standard errors of predicted risks.     

The acceptability, personal outcome expectations, and expected effects of transport pricing policies

Acceptability and personal outcome expectations (i.e., the extent to which one expects to be better or worse off) of transport pricing policies were examined in relation to the expected effects of these policies on one’s own car use, congestion and environmental problems. Car users who commuted frequently by car and experienced congestion on a regular basis evaluated two pricing measures, which were mainly aimed at either decreasing congestion (by tolling at congested areas) or environmental problems (by a differential kilometre charge based on car mass). For the policy mainly aimed to reduce congestion, acceptability was higher and personal outcome expectations were more positive when respondents expected reductions in congestion when the policy was implemented. The policy aimed to reduce environmental problems was more acceptable and respondents expected to be better off in general when they expected reductions in environmental problems after its implementation. Expectations, both about a decrease in congestion and environmental problems were related to respondents’ personal outcome expectations of the policy mainly aimed to decrease environmental problems. We conclude that the acceptability of transport pricing policies are not necessarily low because car users expect negative effects on their car use, but rather because they are not be convinced that transport pricing policies will reduce congestion and environmental problems.     

The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams1

Dosskey, Michael G., Philippe Vidon, Noel P. Gurwick, Craig J. Allan, Tim P. Duval, and Richard Lowrance, 2010. The Role of Riparian Vegetation in Protecting and Improving Chemical Water Quality in Streams. Journal of the American Water Resources Association (JAWRA) 46(2):261-277. DOI: 10.1111/j.1752-1688.2010.00419.x Abstract: We review the research literature and summarize the major processes by which riparian vegetation influences chemical water quality in streams, as well as how these processes vary among vegetation types, and discuss how these processes respond to removal and restoration of riparian vegetation and thereby determine the timing and level of response in stream water quality. Our emphasis is on the role that riparian vegetation plays in protecting streams from nonpoint source pollutants and in improving the quality of degraded stream water. Riparian vegetation influences stream water chemistry through diverse processes including direct chemical uptake and indirect influences such as by supply of organic matter to soils and channels, modification of water movement, and stabilization of soil. Some processes are more strongly expressed under certain site conditions, such as denitrification where groundwater is shallow, and by certain kinds of vegetation, such as channel stabilization by large wood and nutrient uptake by faster-growing species. Whether stream chemistry can be managed effectively through deliberate selection and management of vegetation type, however, remains uncertain because few studies have been conducted on broad suites of processes that may include compensating or reinforcing interactions. Scant research has focused directly on the response of stream water chemistry to the loss of riparian vegetation or its restoration. Our analysis suggests that the level and time frame of a response to restoration depends strongly on the degree and time frame of vegetation loss. Legacy effects of past vegetation can continue to influence water quality for many years or decades and control the potential level and timing of water quality improvement after vegetation is restored. Through the collective action of many processes, vegetation exerts substantial influence over the well-documented effect that riparian zones have on stream water quality. However, the degree to which stream water quality can be managed through the management of riparian vegetation remains to be clarified. An understanding of the underlying processes is important for effectively using vegetation condition as an indicator of water quality protection and for accurately gauging prospects for water quality improvement through restoration of permanent vegetation.     

Measuring the gains from improved air quality in the San Joaquin Valley

Many regions worldwide are experiencing rapid urbanization, and often along with growth in the local economy and population comes worsening air quality. Such regions typically find that addressing the additional challenge of polluted air is difficult. This paper reports the results of an assessment of the present health and related economic costs of poor air quality in the San Joaquin Valley of California. Further, it suggests how such assessments can support strategies to pursue pollution reductions that offer the largest near-term gains, by rigorously modeling the associations between pollution levels, demographic groups, and recognized adverse health effects.