A pilot study of pesticides and PCBs in the breast milk of women residing in urban and agricultural communities of California

Currently, there is no nationally representative human milk biomonitoring program in the United States (U.S.) and no studies have reported non-persistent pesticides in the milk of U.S. women. In this pilot study we developed a multiresidue laboratory method to measure non-persistent and persistent pesticides and polychlorinated biphenyl (PCB) congeners in human milk samples from women residing in the agricultural region of Salinas, CA (n = 13) and the urban San Francisco Bay Area, CA (n = 21). Samples were collected from 2002-2007. Median concentrations in pg g(-1) milk among urban and agricultural women, respectively were reported for: chlorpyrifos (24.5 and 28.0), cis-permethrin (81.9 and 103), trans-permethrin (93.1 and 176), hexachlorobenzene (191 and 223), β-hexachlorocyclohexane (220 and 443), o,p'-DDT (36.6 and 62.4), p,p'-DDT,(107 and 102), o,p'-DDE (5.65 and 5.17), p,p'-DDE (3170 and 3490), dacthal (2.79 and 3.43), PCB 118 (92.8 and 17.0), PCB 138 (183 and 38.2), PCB 153 (242 and 43.6) and PCB 180 (239 and 683). Among urban women, median concentrations were 4.02 and 4.32 pg g(-1) milk for chlorpyrifos-methyl and propoxur, respectively. These results suggest that neonates and young children may be exposed to persistent and non-persistent pesticides and PCBs via breast milk.     

Ocean fertilization for geoengineering: A review of effectiveness,environmental impacts and emerging governance

Dangerous climate change is best avoided by drastically and rapidly reducing greenhouse gas emissions. Nevertheless, geoengineering options are receiving attention on the basis that additional approaches may also be necessary. Here we review the state of knowledge on large-scale ocean fertilization by adding iron or other nutrients, either from external sources or via enhanced ocean mixing. On the basis of small-scale field experiments carried out to date and associated modelling, the maximum benefits of ocean fertilization as a negative emissions technique are likely to be modest in relation to anthropogenic climate forcing. Furthermore, it would be extremely challenging to quantify with acceptable accuracy the carbon removed from circulation on a long term basis, and to adequately monitor unintended impacts over large space and time-scales. These and other technical issues are particularly problematic for the region with greatest theoretical potential for the application of ocean fertilization, the Southern Ocean. Arrangements for the international governance of further field-based research on ocean fertilization are currently being developed, primarily under the London Convention/London Protocol.     

Kinetic modeling of bioavailability for sorbed-phase 2,4-dichlorophenoxyacetic acid

The degradation rate of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in silica-slurry systems to evaluate the bioavailability of sorbed-phase contaminant. After the silica particles were saturated with 2,4-D, the system was inoculated with the 2,4-D-degrading microorganism Flavorbacterium sp. strain FB4. The disappearance rate of 2,4-D was found to be greater than the rate predicted based upon liquid-phase 2,4-D concentrations. A kinetic formulation, termed the enhanced bioavailability model, was developed to describe the desorption and biodegradation processes in this batch system. The approach assumes that 2,4-D resides in both the liquid and solid phases and degradation occurs via both suspended and attached biomass. All biomass can degrade liquid-phase 2,4-D at one rate, while only attached biomass can degrade sorbed 2,4-D at another rate. An enhanced transformation factor (Ef) was introduced to express the increased biodegradation rate over that expected from the liquid phase only. This approach was able to account for the increased degradation rates observed experimentally. The results provide evidence that desorption to the bulk solution is not prerequisite to degradation, and that sorbed substrate may be available for degradation.     

Uptake of gamma-HCH (Lindane) by pipistrelle bats and its effect on survival

Adult pipistrelle bats were caught at two roosts in Eastern England and kept in captivity on an ad lib diet of mealworms. In Experiment 1, two groups of eight bats were each kept in identical outdoor enclosures where the bats could fly freely and where they had a choice of five roost boxes, one of which was heated. One of these groups was exposed to gamma-HCH applied to planed pine blocks which had been immersed in a hexane solution of gamma-HCH. An initial concentration, estimated from surface wood scrapings, of 9.94 +/- 1.15 mg m(-2) was used for the first 44 days, while 866 +/- 51 mg g(-2) was used for a further 44 days. Blocks were placed in the roost boxes to simulate the type of exposure experienced by wild bats. Blocks dosed with solvent alone were given to the other group of bats (controls). Six of the eight bats in the group exposed to gamma-HCH died, while all bats in the control group survived (P < 0.007). In Experiment 2, three groups of five bats were kept in identical cages. Two groups were exposed to identical wood blocks dosed with gamma-HCH, which gave a concentration of 211 mg m(-2) in surface scrapings taken 1-2 h after dosing, while the other group received a wood block treated with solvent alone (control). All bats in the groups exposed to gamma-HCH died within 17 days, while all bats in the control group survived (P < 0.001). Tissues of bats were analysed for gamma-HCH by gas chromatography. There was a critical concentration of 622 +/- 102 microg gamma-HCH g(-1) extractable lipid at which bats died. The total weight of gamma-HCH in bat carcasses was directly related to the weight of extractable lipid. On average, bats died when the gamma-HCH concentration in the whole body reached 27.9 +/- 4.8 microg g(-1), but this value increased as body weight increased. This study confirmed the results of a previous study that gamma-HCH is toxic to bats in conditions simulating exposure in the wild.     

Aging effects on the sorption-desorption characteristics of anthropogenic organic compounds in soil

Field studies have demonstrated that prolonged pesticide-soil contact times (aging) may lead to unexpected persistence of these compounds in the environment. Although this phenomenon is well documented in the field, there have been very few controlled laboratory studies that have tested the effects of long-term aging and the role of differing sorbates on contaminant sorption-desorption behavior and fate in soils. This study examines the sorption-desorption behavior of chlorobenzene, ethylene dibromide (1,2-dibromomethane), atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), and 2, 4-D (2,4-dichlorophenoxyacetic acid) on one soil type after 1 d, 30 d, and 14 mo of aging. Sorption isotherms were evaluated after each aging period to observe changes in the uptake of each compound by soil. Desorption kinetic data were generated after each aging period to observe changes in release from soil, and desorption parameters were evaluated using a three-site desorption model that includes equilibrium, nonequilibrium, and nondesorption sites. The data indicate no statistically significant increase in sorption for ethylene dibromide or chlorobenzene from 1 to 30 d, although sorption of 2,4-D increased slightly, and sorption of atrazine decreased slightly. Statistically significant increases in linear sorption coefficients (Kd), from 1 d to 14 mo of aging, were apparent for ethylene dibromide and 2,4-D. The Kd values for chlorobenzene, measured after 1 d, 30 d, and 14 mo of aging, were statistically indistinguishable. Aging affected the distribution of chemicals within sorption sites. With aging, the desorbable fraction decreased and the nondesorbable fraction, which was apparent after only 1 d of pesticide-soil contact, increased for all chemicals studied.     

Surprising cooperation despite apparently irreconcilable differences: Agricultural water use efficiency and CALFED

Much has been said about the need and benefits of consensus building for resolving disagreements about water and environmental management. Less has been said about how to better convene and facilitate those processes. This paper focuses on the latter, examining the challenges and breakthroughs encountered when decision-makers convene consensus building processes that seek an agreement among stakeholders who believe they have “apparently irreconcilable differences.” The research described here analyzes two multi-stakeholder, collaborative processes convened by the CALFED Bay-Delta Program (CALFED) on the issue of agricultural water use efficiency in the Sacramento and San Joaquin river watersheds of California. The first process made very little progress; however, stakeholder representatives in the second were able to forge an agreement that included significant innovation and surprising risk taking by all sides. Analyzing the two processes, this paper shows that the stakeholders, conveners, and facilitators in these processes had to do much more than make the discrete trades across interests envisioned in consensus building theory or reframing as described in theories about conflict and frames. Looking at the data, this paper shows how several concepts from outside consensus building—including boundary objects and interlanguage—along with less well-known concepts and issues within the consensus building literature—bricolage and representation—can provide insights into how the Steering Committee accomplished what it did. This paper introduces these additional concepts, how they mattered in this CALFED process, and suggests a complex set of interrelated insights into how future collaborative and integrative environmental programs can approach the most difficult environmental policy and management conflicts.     

Spatial and temporal occurrence of N-nitrosamines in seven drinking water supply systems

The spatiotemporal presence of eight N-nitrosamines in the water of seven supply systems in Quebec considered to be susceptible to these emerging disinfection by-products was evaluated. This is the first study on the presence of N-nitrosamines in drinking water utilities in Quebec. Seven sampling campaigns were carried out at several sampling points in each of the systems over a period of 1 year. The results show that N-nitrosamines, primarily N-nitrosodimethylamine (NDMA), were not commonly detected in the water of the facilities under study (10 % of samples). The concentrations measured were lower than those reported in recent North American studies. None of the 195 samples taken exceeded the Ontario standard of 9 ng/L for NDMA (maximum value observed of 3.3 ng/L). N-nitrosomethylethylamine and N-nitrosopiperidine were detected once, with concentrations of 3.7 and 6.0 ng/L, respectively. Chloramination was identified as being the main risk factor regarding the presence of N-nitrosamines, but water quality and some operating parameters, in particular disinfectant residual, also seem to be related to their presence. NDMA concentrations at the end of the distribution systems were generally higher than water leaving the plant. No seasonal trends were observed for the formation of N-nitrosamines in the investigated supply systems. Finally, an association between the presence of N-nitrosamines and the levels of trihalomethanes and haloacetic acids was observed in some facilities.     

2,4,6-Trinitrotoluene mineralization and bacterial production rates of natural microbial assemblages from coastal sediments

The nitrogenous energetic constituent, 2,4,6-Trinitrotoluene (TNT), is widely reported to be resistant to bacterial mineralization (conversion to CO₂); however, these studies primarily involve bacterial isolates from freshwater where bacterial production is typically limited by phosphorus. This study involved six surveys of coastal waters adjacent to three biome types: temperate broadleaf, northern coniferous, and tropical. Capacity to catabolize and mineralize TNT ring carbon to CO₂ was a common feature of natural sediment assemblages from these coastal environments (ranging to 270+/−38 μg C kg⁻¹ d⁻¹). More importantly, these mineralization rates comprised a significant proportion of total heterotrophic production. The finding that most natural assemblages surveyed from these ecosystems can mineralize TNT ring carbon to CO₂ is consistent with recent reports that assemblage components can incorporate TNT ring carbon into bacterial biomass. These data counter the widely held contention that TNT is recalcitrant to bacterial catabolism of the ring carbon in natural environments.     

Lactational transfer of mercury and polychlorinated biphenyls in polar bears

We examined concentrations of total mercury (tHg, inorganic and methylated forms) and polychlorinated biphenyls (PCBs) in blood and milk from free-ranging Southern Beaufort-Chukchi Sea polar bears (Ursus maritimus) to assess maternal transfer of contaminants during lactation and the potential health risk to nursing young. Concentrations of contaminants in the blood of dependent and juvenile animals (ages 1-5 years) ranged from 35.9 to 52.2 μg kg(-1) ww for tHg and 13.9 to 52.2 μg kg(-1) ww (3255.81-11067.79 μg kg(-1) lw) for ΣPCB(7)s, similar to those of adult females, but greater than adult males. Contaminant concentrations in milk ranged from 5.7 to 71.8 μg tHg kg(-1)ww and 160 to 690 μg ΣPCB(11)s kg(-1) ww (547-5190 μg kg(-1) lw). The daily intake levels for tHg by milk consumption estimated for dependent young were below the tolerable daily intake level (TDIL) of tHg established for adult humans. Although the daily intake levels of PCBs through milk consumption for cubs of the year exceeded the TDIL thresholds, calculated dioxin equivalents for PCBs in milk were below adverse physiological thresholds for aquatic mammals. Relatively high concentrations of non-dioxin like PCBs in polar bear milk and blood could impact endocrine function of Southern Beaufort-Chukchi Sea polar bears, but this is uncertain. Transfer of contaminants during mid to late lactation likely limits bioaccumulation of dietary contaminants in female polar bears during spring. As polar bears respond to changes in their arctic sea ice habitat, the adverse health impacts associated with nutritional stress may be exacerbated by tHg and PCBs exposure, especially in ecologically and toxicologically sensitive polar bear cohorts such as reproductive females and young.