Cynthia A. de Wit

A safe operating space for humanity

Identifying and quantifying planetary boundaries that must not be transgressed could help prevent human activities from causing unacceptable environmental change, argue Johan Rockstrom and colleagues.

An overview of brominated flame retardants in the environment

The presence of brominated flame retardant (BFR) chemicals, and particularly polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD), has become of increasing concern to scientists over the past decade. Environmental studies conducted primarily in Europe, Japan and North America indicate that these chemicals are ubiquitous in sediment and biota. The levels of PBDEs seem to be increasing, and several trends, including in humans, indicate that this increase may be rapid. The occurrence of high concentrations of certain PBDE isomers may be sufficient to elicit adverse effects in some wildlife. There is also concern that levels could cause adverse effects in sensitive human populations such as young children, indigenous peoples, and fish consumers. However, our knowledge about these chemicals, their sources, environmental behavior, and toxicity is limited, making risk assessment difficult. In this paper, the current state of knowledge is reviewed and areas for further research recommended to improve future monitoring and risk assessment efforts.

Planetary boundaries: Guiding human development on a changing planet

Crossing the boundaries in global sustainability The planetary boundary (PB) concept, introduced in 2009, aimed to define the environmental limits within which humanity can safely operate. This approach has proved influential in global sustainability policy development. Steffen et al. provide an updated and extended analysis of the PB framework. Of the original nine proposed boundaries, they identify three (including climate change) that might push the Earth system into a new state if crossed and that also have a pervasive influence on the remaining boundaries. They also develop the PB framework so that it can be applied usefully in a regional context. Science, this issue 10.1126/science.1259855 Developments in the planetary boundaries concept provide a framework to support global sustainability. INTRODUCTION There is an urgent need for a new paradigm that integrates the continued development of human societies and the maintenance of the Earth system (ES) in a resilient and accommodating state. The planetary boundary (PB) framework contributes to such a paradigm by providing a science-based analysis of the risk that human perturbations will destabilize the ES at the planetary scale. Here, the scientific underpinnings of the PB framework are updated and strengthened. RATIONALE The relatively stable, 11,700-year-long Holocene epoch is the only state of the ES that we know for certain can support contemporary human societies. There is increasing evidence that human activities are affecting ES functioning to a degree that threatens the resilience of the ES—its ability to persist in a Holocene-like state in the face of increasing human pressures and shocks. The PB framework is based on critical processes that regulate ES functioning. By combining improved scientific understanding of ES functioning with the precautionary principle, the PB framework identifies levels of anthropogenic perturbations below which the risk of destabilization of the ES is likely to remain low—a “safe operating space” for global societal development. A zone of uncertainty for each PB highlights the area of increasing risk. The current level of anthropogenic impact on the ES, and thus the risk to the stability of the ES, is assessed by comparison with the proposed PB (see the figure). RESULTS Three of the PBs (climate change, stratospheric ozone depletion, and ocean acidification) remain essentially unchanged from the earlier analysis. Regional-level boundaries as well as globally aggregated PBs have now been developed for biosphere integrity (earlier “biodiversity loss”), biogeochemical flows, land-system change, and freshwater use. At present, only one regional boundary (south Asian monsoon) can be established for atmospheric aerosol loading. Although we cannot identify a single PB for novel entities (here defined as new substances, new forms of existing substances, and modified life forms that have the potential for unwanted geophysical and/or biological effects), they are included in the PB framework, given their potential to change the state of the ES. Two of the PBs—climate change and biosphere integrity—are recognized as “core” PBs based on their fundamental importance for the ES. The climate system is a manifestation of the amount, distribution, and net balance of energy at Earth’s surface; the biosphere regulates material and energy flows in the ES and increases its resilience to abrupt and gradual change. Anthropogenic perturbation levels of four of the ES processes/features (climate change, biosphere integrity, biogeochemical flows, and land-system change) exceed the proposed PB (see the figure). CONCLUSIONS PBs are scientifically based levels of human perturbation of the ES beyond which ES functioning may be substantially altered. Transgression of the PBs thus creates substantial risk of destabilizing the Holocene state of the ES in which modern societies have evolved. The PB framework does not dictate how societies should develop. These are political decisions that must include consideration of the human dimensions, including equity, not incorporated in the PB framework. Nevertheless, by identifying a safe operating space for humanity on Earth, the PB framework can make a valuable contribution to decision-makers in charting desirable courses for societal development. Current status of the control variables for seven of the planetary boundaries. The green zone is the safe operating space, the yellow represents the zone of uncertainty (increasing risk), and the red is a high-risk zone. The planetary boundary itself lies at the intersection of the green and yellow zones. The control variables have been normalized for the zone of uncertainty; the center of the figure therefore does not represent values of 0 for the control variables. The control variable shown for climate change is atmospheric CO2 concentration. Processes for which global-level boundaries cannot yet be quantified are represented by gray wedges; these are atmospheric aerosol loading, novel entities, and the functional role of biosphere integrity. The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed.

Brominated flame retardants in the Arctic environment - trends and new candidates.

Polybrominated diphenyl ethers (PBDEs) containing two to 10 bromines are ubiquitous in the Arctic, in both abiotic and biotic samples. Hexabromocyclododecane (HBCD) is also ubiquitous in the Arctic, with the gamma-HBCD isomer predominating in air, the alpha-HBCD isomer predominating in biota and similar concentrations of alpha-, beta- and gamma-HBCD found in marine sediments. Other brominated flame retardants (BFRs) found in some Arctic samples are polybrominated biphenyls (PBBs), tetrabromobisphenol A (TBBPA), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), hexabromobenzene (HxBBz), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH). Temporal trends of tetra- to heptaBDEs and HBCD show increasing concentrations or a tendency to levelling off depending on the matrix (air, sediment, biota) and location, but no uniform picture for the Arctic emerges. BDE-209 concentrations are increasing in air. PBDEs and HBCD spatial trends in seabirds and marine mammals are similar to those seen previously for polychlorinated biphenyls (PCBs), with highest concentrations found in organisms from East Greenland and Svalbard. These trends indicate western Europe and eastern North America as important source regions of these compounds via long range atmospheric transport and ocean currents. Latitudinal trends showed lower concentrations and fluxes of PBDEs at higher latitudes. The tetra-hexaBDEs and alpha-HBCD biomagnify in Arctic food webs. Results for BDE-209 are more conflicting, showing either only low or no biomagnification potential. PBDE and HBCD concentrations are lower in terrestrial organisms and higher in marine top predators such as some killer whale populations in Alaska and glaucous gulls from the Barents Sea area. Higher concentrations are seen near populated areas indicating local sources. Findings of BTBPE, HxBBz, PBEB, PBT and TBECH in seabirds and/or marine mammals indicate that these compounds reach the Arctic, most probably by long range atmospheric transport and accumulate in higher trophic level organisms and that increasing use as PBDE replacements will lead to increasing concentrations.

Polybrominated diphenyl ethers (PBDE) in biological samples from the Swedish environment

Abstract Polybrominated diphenyl ethers, PBDE, are widespread contaminants in the Swedish environment and are present in both background and industrialised areas. This study presents results from analyses of a variety of species from different sampling sites in Sweden. The spatial trend along the Swedish coast is similar to that of polychlorinated biphenyls (PCB) and the DDTs. PBDE seem to bio-magnify in fish consumers like grey seal and guillemot (egg). The relative amounts of the investigated tetra- and pentabrominated PBDE congeners are different in different species and in different areas. The importance of a sampling strategy when doing time-trend studies is demonstrated for guillemot eggs.

Trends of legacy and new persistent organic pollutants in the circumpolar arctic: Overview, conclusions, and recommendations☆

This article provides an overview of key findings in the reviews in this special issue on the assessment of persistent organic pollutants (POPs) under the Arctic Monitoring and Assessment Program (AMAP), identifies knowledge gaps, and presents conclusions and recommendations for future work. The articles in this special issue summarize the peer reviewed literature and selected technical reports on trends of concentrations and possible biological effects of POPs in the Arctic published up to early 2009.

Tri-decabrominated diphenyl ethers and hexabromocyclododecane in indoor air and dust from Stockholm microenvironments 1: levels and profiles.

Indoor air (gas and particle phase) and dust samples were collected from 10 houses, 44 apartments, 10 day care centers, 10 offices, 17 new cars and two car dealership halls from Stockholm, Sweden, and analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). Median ΣPBDE concentrations in air were 330, 58, 4000, 14000 and 510 pg/m(3) in houses, apartments, day care centers, offices and cars, respectively. Median ΣPBDE concentrations in dust were 510, 1400, 1200, 1200 and 1400 ng/g in houses, apartments, day care centers, offices and cars, respectively. HBCD was detected in most dust samples (median range, 45-340 ng/g) but only in a few air samples (median range, <1.6-2.0 pg/m(3)). For all microenvironments, the brominated flame retardant (BFR) found in highest concentration in air was ΣDecaBDE, primarily BDE-209, followed by ΣPentaBDE, and in dust, ΣDecaBDE, followed by HBCD (offices, day care centers, cars) or ΣPentaBDE (houses, apartments). Positive correlations were found between matched air and dust samples for ΣPentaBDE, but not for ΣDecaBDE.

Tri-decabrominated diphenyl ethers and hexabromocyclododecane in indoor air and dust from Stockholm microenvironments 2: Indoor sources and human exposure

Data on polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) concentrations from Stockholm, Sweden, indoor microenvironments were combined with information from detailed questionnaires regarding the sampling location characteristics, including furnishing and equipment present. These were used to elucidate relationships between possible flame-retarded sources and the contaminant concentrations found in air and dust. Median concentration ranges of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD from all microenvironments were 19-570, 1.7-280, 29-3200 and <1.6-2 pg/m(3) in air and 22-240, 6.1-80, 330-1400 and 45-340 ng/g in dust, respectively. Significant correlations were found between concentrations of some PBDEs and HBCD in air and/or dust and the presence of electronic/electrical devices, foam furniture, PUF mattresses and synthetic bed pillows in, as well as floor area and construction year of the microenvironment. Car interiors were a source to indoor air in dealership halls. Using median and maximum concentrations of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD in air and dust, adult and toddler (12-24 months) intakes from inhalation and dust ingestion were estimated. Toddlers had higher estimated intakes of ΣPenta-, ΣDecaBDE and HBCD (7.8, 43, 7.6 ng/d, respectively) from dust ingestion than adults (5.8, 38, 6.0 ng/d, respectively). Air inhalation in offices was also an important exposure pathway for ΣPenta-, ΣOcta- and ΣDecaBDE in adults. For ΣPentaBDE and HBCD, air inhalation and dust ingestion play minor roles when compared to previously published Swedish dietary intakes (median exposures). However, in worst case scenarios using maximum concentrations, dust ingestion may represent 77 and 95% of toddler intake for ΣPentaBDE and HBCD, respectively.

San Antonio Statement on Brominated and Chlorinated Flame Retardants

We, scientists from a variety of disciplines, declare the following: Parties to the Stockholm Convention have taken action on three brominated flame retardants that have been listed in the treaty for global elimination. These substances include components of commercial penta-bromodiphenyl ether and commercial octa-bromodiphenyl ether, along with hexabromobiphenyl. Another brominated flame retardant, hexabromocyclododecane, is under evaluation. Many commonly used brominated and chlorinated flame retardants can undergo long-range environmental transport. Many brominated and chlorinated flame retardants appear to be persistent and bioaccumulative, resulting in food chain contamination, including human milk. Many brominated and chlorinated flame retardants lack adequate toxicity information, but the available data raises concerns. Many different types of brominated and chlorinated flame retardants have been incorporated into products even though comprehensive toxicological information is lacking. Brominated and chlorinated flame retardants present in a variety of products are released to the indoor and outdoor environments. Near-end-of-life and end-of-life electrical and electronic products are a growing concern as a result of dumping in developing countries, which results in the illegal transboundary movement of their hazardous constituents. These include brominated and chlorinated flame retardants. There is a lack of capacity to handle electronic waste in an environ-mentally sound manner in almost all developing countries and countries with economies in transition, leading to the release of hazardous substances that cause harm to human health and the environment. These substances include brominated and chlorinated flame retardants. Brominated and chlorinated flame retardants can increase fire toxicity, but their overall benefit in improving fire safety has not been proven. When brominated and chlorinated flame retardants burn, highly toxic dioxins and furans are formed. Therefore, these data support the following: Brominated and chlorinated flame retardants as classes of substances are a concern for persistence, bioaccumulation, long-range transport, and toxicity. There is a need to improve the availability of and access to information on brominated and chlorinated flame retardants and other chemicals in products in the supply chain and throughout each product’s life cycle. Consumers can play a role in the adoption of alternatives to harmful flame retardants if they are made aware of the presence of the substances, for example, through product labeling. The process of identifying alternatives to flame retardants should include not only alternative chemicals but also innovative changes in the design of products, industrial processes, and other practices that do not require the use of any flame retardant. Efforts should be made to ensure that current and alternative chemical flame retardants do not have hazardous properties, such as mutagenicity and carcinogenicity, or adverse effects on the reproductive, developmental, endocrine, immune, or nervous systems. When seeking exemptions for certain applications of flame retardants, the party requesting the exemption should supply some information indicating why the exemption is technically or scien-tifically necessary and why potential alternatives are not technically or scientifically viable; a description of potential alternative processes, products, materials, or systems that eliminate the need for the chemical; and a list of sources researched. Wastes containing flame retardants with persistent organic pollutant (POP) characteristics, including products and articles, should be disposed of in such a way that the POP content is destroyed or irreversibly transformed so that they do not exhibit the charac-teristics of POPs. Flame retardants with POP characteristics should not be permitted to be subjected to disposal operations that may lead to recovery, recycling, reclamation, direct reuse, or alternative uses of the substances. Wastes containing flame retardants with POP properties should not be transported across international boundaries unless it is for disposal in such a way that the POP content is destroyed or irreversibly transformed. It is important to consider product stewardship and extended producer responsibility aspects in the life-cycle management of products containing flame retardants with POP properties, including electronic and electrical products.

Polybrominated diphenyl ether congener patterns, hexabromocyclododecane, and brominated biphenyl 153 in eggs of peregrine falcons (Falco peregrinus) breeding in Sweden

Previous analyses of 52 peregrine falcon (Falco peregrinus) eggs collected from two wild and one captive population in Sweden 1987 through 1999 were complemented by including additional polybrominated diphenyl ether (PBDE) congeners (BDE-35, -183, -184, -185, -196, -197, -203, and -207). In addition, 31 eggs not previously analyzed for hexabromocyclododecane (HBCD) and BDE-209 were analyzed for these. Geometric mean concentrations of BPBDEs, HBCD, and the hexabrominated biphenyl (BB-153) were 3,100, 140, and 81 ng/g of lipid weight for the southern population; 2,500, 110, and 84 ng/g of lipid weight for the northern population; and 47, not detected, and 8 ng/g of lipid weight for the captive population. The BDE congener pattern was dominated by BDE-153, -99, and -100. The results were used to investigate whether a difference in PBDE congener pattern could be distinguished between the two wild populations of peregrine falcons due to different diets, as the southern population preys mainly on birds belonging to the terrestrial food chain while the northern population preys more on aquatic birds. A multivariate t-test showed a subtle but significant (p < 0.001) difference in PBDE congener pattern between the two populations. However, our hypothesis that higher-brominated congeners of PBDEs would be present to a greater extent in the terrestrial food chain was not supported by principal component analysis. The average brood size for individual females from the southern population decreased with increasing concentrations of IPBDE in the eggs (log-linear regression p < 0.01).