Application of Uncertainty Factors in the Priority Substances Program and International Harmonization

The Canadian Environmental Protection Act (CEPA) authorizes the Ministers of the Environment and of Health in Canada to investigate a wide variety of substances that may contaminate the environment and cause adverse effects on the environment and/or on human health. Under the Act, assessments have been completed for 44 environmental contaminants on the first Priority Substances List (PSL) and are relatively advanced for 25 compounds on the second PSL. The principles developed for the application of uncertainty factors in assessment of risks to human health for Priority Substances under CEPA are outlined, with emphasis on those aspects which are somewhat unique and/or evolving. The interface of developments in the Priority Substances program with an initiative of the International Programme on Chemical Safety in this area to effect greater harmonization of approaches is also described.     

A Review of the Legal and Policy Framework for Vessel Source Pollution in Hong Kong

Vessel source marine pollution is an increasingly major concern at both the national and international levels. Hong Kong, as an important maritime center, is naturally concerned with vessel source pollution. To meet the challenges, Hong Kong has formulated policies and measures that emphasize “green shipping” as part of an overall planning strategy that promotes a “green economy.” This article provides a review and analysis of Hong Kong's marine pollution laws, with a view toward making policy suggestions. It argues that the general perception of the adequacy of Hong Kong's marine laws in combating vessel source pollution is flawed. It suggests that Hong Kong should adopt a more forward-looking perspective in the formulation of legal measures to control vessel source pollution.     

Risk Analysis,Uncertainty Factors,and the Susceptibilities of Children

This article examines the use of uncertainty factors (UFs) by the Agency for Toxic Substances and Disease Registry (ATSDR) when developing health guidance values known as minimal risk levels (MRLs) in environmental risk analysis as it applies to children. Improvements in the chemical-specific databases often reveal new information and thereby reduce uncertainty or alternatively raise new concerns. As a result, MRLs can and will change. Children, in particular, are not “small adults” and in some instances demonstrate greater risks of exposure to environmental toxicants and greater susceptibility for adverse health effects once exposed. Recent experience with risk analysis for three toxicants (organic mercury, dioxin, and manganese) is recounted to demonstrate how ATSDR has revised MRLs as the emerging science generates greater knowledge and awareness of children's special vulnerabilities to toxic substances in the environment.     

Sentinel Human Health Indicators: A Model for Assessing Human Health Status of Vulnerable Communities

The presence of toxic substances in the Great Lakes (GL) continues to be a significant concern. Eleven of the most persistent and ubiquitous substances were identified as “critical Great Lakes pollutants” by the International Joint Commission (IJC). In some areas of the GL these toxic substances bioaccumulate in sediment and organisms, biomagnify in food webs, and persist at high levels. The Agency for Toxic Substances and Disease Registry (ATSDR) Great Lakes Human Health Effects Research Program (GLHHERP) characterizes contaminant exposures via GL fish consumption and investigates the potential for short- and long-term adverse health effects. The program has identified a set of eight indicators to determine risk. The GLHHERP findings indicate: (1) vulnerable populations are still being exposed to persistent toxic substances (2) body burden levels are two to four times higher than in the general U.S. population, (3) women and minorities are less knowledgeable about fish advisories than other segments of the population, (4) the presence of neurodevelopmental deficits in newborns, and cognitive deficits in children and adults, and (5) disturbances in reproductive parameters have been demonstrated in adults. The public health implications of these findings and the need for intervention strategies are discussed.     

Considering human toxicity as an impact category in life cycle assessment

Characterization of toxic chemicals with relevance to human exposure does normally not belong to Life Cycle Assessments (LCA) and is still a topic of research. The concept of hazard potential classes proposed in this paper is primarily based on threshold limit values that are considered to be a measure of the severity of potential effects. In the absence of threshold limit values the R-phrases of the ordinance of dangerous substances are used. Substances are assigned to five hazard potential classes (A to E). Potentially dangerous chemicals are identified and substances of low toxicological relevance are excluded from further evaluation. The location where a probable exposure might occur (indoor versus outdoor) and inter-media transport of substances is considered. The product comparison is based both on the results of the proposed “semi-quantitative screening method” and on toxicological expert knowledge.     

Harnessing microbial activities for environmental cleanup

Human activities have released large amounts of toxic organic and inorganic chemicals into the environment. Toxic waste streams threaten dwindling drinking water supplies and impact terrestrial, estuarine and marine ecosystems. Cleanup is technically challenging and the costs based on traditional technologies are exceeding the economic capabilities of even the richest countries. Recent advances in our understanding of the microbiology contributing to contaminant transformation and detoxification has led to successful field demonstrations. Hence, harnessing the activity of naturally occurring bacteria, particularly the power of anaerobic reductive processes, is a promising approach to restore contaminated subsurface environments, protect drinking water reservoirs and to safeguard ecosystem health.     

运用分子生物学技术监测水环境中产毒蓝藻

有毒蓝藻在形成水华破坏水体环境的同时,也对人畜产生危害。运用分子生物学技术对水环境中产毒蓝藻进行监测,由于其简单、快速和经济等优点,逐渐成为各国学者关注的热点。本文从以下3个方面对其进行了综述:1)早期分子生物学技术在产毒蓝藻诊断中的运用;2)以产毒基因为靶标进行的产毒蓝藻诊断;3)运用基因芯片技术对产毒蓝藻进行检测。与传统的分子生物学技术相比,生物芯片技术具有体积小、重量轻、便于携带、分析自动快速、高通量等许多传统方法所不能比拟的优势。因此,该技术在蓝藻毒素检测中的运用必将给目前的产毒蓝藻的检测带来一场新的革命。     

Risk Assessment Using EUSES; Refinement Options to Estimate Atmospheric Transportation by its Operational Priority Substances Model (OPS)

The Operational Priority Substances (OPS) model is part of the European Union System for the Evaluation of Substances (EUSES) and is used to estimate air concentrations and atmospheric depositions for risk assessment of chemicals. Traditionally, EUSES assesses environmental exposure using a standardized scenario based on explicit assumptions and default parameter settings. Under the new European Union REACH legislation—which stands for Registration, Evaluation, Authorisation, and restriction of Chemicals—industry is responsible for the risk assessment of chemicals. The current work investigates the potential impact and importance of source parameter refinement on the emission distribution and environmental fate of chemicals as modelled by OPS. In total, 60 scenarios with different combinations of (non) default values for emission heat content, emission source height, and emission source radius, were run for a typical particle-bound substance. Increasing heat content and emission source height reduced the modelled air concentrations and depositions and caused maximum air concentrations to occur further away from the emission source. Results show that estimated air concentrations and total depositions used for risk assessment can become more realistic by using more site-specific emission source parameters. This article proposes risk assessment refinement options and provides recommendations on future updates of EUSES.     

Influence of Criconemella xenoplax and Pruning Time on Short Life of Peach Trees

Influences of Criconemella xenoplax and pruning dates were studied in field microplots with ''Nemaguard'' peach cuttings on a site not previously planted to peaches. Trees with or without C. xenoplax were pruned beginning in December 1984 or March 1985. Peach tree short life (PTSL) did not occur in the absence of C. xenoplax. PTSL occurred earlier in December-pruned than in March-pruned inoculated trees. Results confirm that "old" peach sites are not required for PTSL to occur. Pruning Nemaguard and ''Lovell'' greenhouse-grown seedlings reduced the root mass of both stocks and stimulated Nemaguard, but not Lovell, shoot regrowth. Numbers of C. xenoplax per gram of dry root were greater on pruned than on unpruned seedlings.     

Leveraging high-throughput screening data,deep neural networks,and conditional generative adversarial networks to advance predictive toxicology

There are currently 85,000 chemicals registered with the Environmental Protection Agency (EPA) under the Toxic Substances Control Act, but only a small fraction have measured toxicological data. To address this gap, high-throughput screening (HTS) and computational methods are vital. As part of one such HTS effort, embryonic zebrafish were used to examine a suite of morphological and mortality endpoints at six concentrations from over 1,000 unique chemicals found in the ToxCast library (phase 1 and 2). We hypothesized that by using a conditional generative adversarial network (cGAN) or deep neural networks (DNN), and leveraging this large set of toxicity data we could efficiently predict toxic outcomes of untested chemicals. Utilizing a novel method in this space, we converted the 3D structural information into a weighted set of points while retaining all information about the structure. In vivo toxicity and chemical data were used to train two neural network generators. The first was a DNN (Go-ZT) while the second utilized cGAN architecture (GAN-ZT) to train generators to produce toxicity data. Our results showed that Go-ZT significantly outperformed the cGAN, support vector machine, random forest and multilayer perceptron models in cross-validation, and when tested against an external test dataset. By combining both Go-ZT and GAN-ZT, our consensus model improved the SE, SP, PPV, and Kappa, to 71.4%, 95.9%, 71.4% and 0.673, respectively, resulting in an area under the receiver operating characteristic (AUROC) of 0.837. Considering their potential use as prescreening tools, these models could provide in vivo toxicity predictions and insight into the hundreds of thousands of untested chemicals to prioritize compounds for HT testing.     

Chinatown UK v. Colonial Hong Kong: An early exercise in transnational militancy and manipulation, 1967–1969

In the late 1960s, Hong Kong was hit by a wave of social and political unrest, an echo in the colony of China's Cultural Revolution of 1966–69. The unrest spread to parts of Britain's Chinatown, where a leftist movement emerged in sympathy with the Hong Kong agitation. Among the Chinatown leftists were former supporters of the Communist anti-Japanese guerrillas in Hong Kong's rural New Territories. The colonial authorities reacted to these developments in Britain by drawing up plans to protect and assist overseas Hong Kong residents in an attempt to win their political approval and stymie the pro-Communists. The Hong Kong Government Office [HKGO] in London started providing materials for Chinese-language schools and set up various other communal services. Later, it launched a campaign to foster the emigrants’ “Hong Kong identity”. The scheme was in many ways successful. Chinatowners were usually happy to make use of the facilities on offer. However, there is little evidence that the HKGO succeeded in winning their political allegiance.     

Human Health Impact as a Boundary Selection Criterion in the Life Cycle Assessment of Pultruded Fiber Reinforced Polymer Composite Materials

The human health impact of fiber reinforced polymer (FRP) composite materials manufactured by the pultrusion industry is not fully understood. In particular, it is unclear whether the human health impact of toxic chemicals present in low concentrations in fire retardant pultruded FRP materials is disproportionately high. This impact may be an important criterion when making boundary selection decisions in the life cycle assessment (LCA) of these materials. The North American pultrusion industry was surveyed to determine resin mix concentration levels and workplace inhalation toxicity exposure levels. LCAs were then conducted on three building panel resin mixes to determine whether the human health impact of toxic chemicals used in the mixes was low enough to exclude the chemicals from the life cycle inventory (LCI) boundary. The first resin mix represented a typical pultruded product, the second mix removed toxic chemicals present in small concentrations, and the third mix replaced toxic chemicals present in small concentrations with a nontoxic chemical. Results showed that toxicity levels fell below exposure limits and no significant difference in human health impact existed among the LCAs. The research concludes that human health impact is a useful criterion when defining an LCI boundary. Toxic chemicals present in small concentrations in pultruded FRP materials may be excluded from the LCI boundary, as their human health impacts are low. Because these levels are marginal in North American pultrusion factories, no changes in resin mixes are recommended for the pultrusion industry.     

Three Primary Color Wheel

This longitudinal study (2001–09) of two Hong Kong secondary schools highlights six issues with an integrated arts curriculum: first, integration of knowledge and skills negatively precedes the integration of learners’ construction of meaning; second, integration is perceived as challenging the profession's status; third, teachers are unaccustomed to co-teaching; fourth, teachers have little prior experience conceptualizing cross-discipline teaching and learning; fifth, Hong Kong's current systemwide education reform places arts integration as a relatively low priority; and sixth, because integrated arts curriculum implementation is not mandatory, the vagaries of individual school management create a plethora of integration approaches that confound the task of forging a common definition. Remedial recommendations include cascading “seed projects” to broaden teachers’ views of integrated arts and teaching, facilitating supportive school timetabling, and sharing integrated learning outcomes in the individual schools.     

Chemical Contamination of California Drinking Water

Drinking water contamination by toxic chemicals has become widely recognized as a public health concern since the discovery of 1,2-dibromo-3-chloropropane in California''s Central Valley in 1979. Increased monitoring since then has shown that other pesticides and industrial chemicals are present in drinking water. Contaminants of drinking water also include naturally occurring substances such as asbestos and even the by-products of water chlorination. Public water systems, commercially bottled and vended water and mineral water are regulated, and California is also taking measures to prevent water pollution by chemicals through various new laws and programs.     

Mercury in traditional medicines: is cinnabar toxicologically similar to common mercurials?

Mercury is a major toxic metal ranked top in the Toxic Substances List. Cinnabar, which contains mercury sulfide, has been used in Chinese traditional medicines for thousands of years as an ingredient in various remedies, and 40 cinnabar-containing traditional medicines are still used today. Little is known about toxicology profiles or toxicokinetics of cinnabar and cinnabar-containing traditional medicines, and the high mercury content in these Chinese medicines raises justifiably escalations of public concern. This minireview, by searching the available database of cinnabar and by comparing cinnabar with common mercurials, discusses differences in their bioavailability, disposition, and toxicity. The analysis showed that cinnabar is insoluble and poorly absorbed from the gastrointestinal tract. Absorbed mercury from cinnabar is mainly accumulated in the kidneys, resembling the disposition pattern of inorganic mercury. Heating cinnabar results in release of mercury vapor, which in turn can produce toxicity similar to inhalation of these vapors. The doses of cinnabar required to produce neurotoxicity are 1000 times higher than methyl mercury. Following long-term use of cinnabar, renal dysfunction may occur. Dimercaprol and succimer are effective chelation therapies for general mercury intoxication including cinnabar. Pharmacological studies of cinnabar suggest sedative and hypnotic effects, but the therapeutic basis of cinnabar is still not clear. In summary, cinnabar is chemically inert with a relatively low toxic potential when taken orally. In risk assessment, cinnabar is less toxic than many other forms of mercury, but the rationale for its inclusion in traditional Chinese medicines remains to be fully justified.     

Hazards from chemicals: scientific questions and conflicts of interest.

All substances are toxic when the dose is large enough. In order to regulate the use of chemicals, we need to measure the level at which toxic effects are found. Epidemiological evidence suggests that present levels of chemical use do not lead to widespread harmful contamination of the human environment. For chemicals, most of the problems of toxicity are found in the workplace, while the population at large gets most of its toxic effects from voluntary exposure to substances such as tobacco smoke and ethanol. The prevention and control of toxic effects depends on a series of steps. This begins with measurement of toxicity in model systems, such as laboratory animals, and the estimation of the likely exposure of workers or consumers. Reliable extrapolation of information gathered from animals to the diverse and biochemically differing human population depends on understanding mechanisms of toxic effects. The toxic effect and mechanisms of action of substances such as carbon tetrachloride or paracetamol have been extensively investigated, and our ability to predict toxicity or develop antidotes to poisoning has had some success, but epidemiology is still an essential part of assessment of toxic effects of new chemicals. The example of phenobarbitone shows how animal experiments may well lead to conclusions which do not apply to man. After measurement of toxicity and assessment of likely hazards in use comes the final evaluation of the use of a chemical. This depends not only on its toxicity, but also on its usefulness. The direct effects on health may be small in comparison with the indirect advantageous effects which a useful substance such as vinyl chloride may bring. The assessment of risks and benefits of new chemicals can be partly removed from a political style of discourse, but the evaluation of the relative weight to be attached to these risks and benefits is inescapably political. The scientific contribution must be to allow the debate to take place in the light of maximum clarity of information about the consequences of use of chemicals.     

Release of ethane from immobilised plant cell protoplasts in response to chemical treatment

In isolated protoplasts of Vicia faba L. (cv. Weißkernige Hangdown) which were immobilised in a cross-linked alginate matrix, ethane production and ribulose bisphosphate carboxylase (RuBP carboxylase) aetivity were determined after treatment of the alginate strips with various chemical substances.
The stimulation of ethane formation and the inhibition of RuBP carboxylase activity by the toxic materials might provide the basis for a simple, rapid and sensitive system for the determination of chemicals in the environment.     

Shifting tides of world-making in the UNESCO World Heritage Convention: cosmopolitanisms colliding

The success of UNESCO's 1972 World Heritage Convention has made an entry into the World Heritage List a coveted distinction for tourism, nation-building and economic development. This article traces the evolution of the treaty from sharing responsibility for humanity's most prized sites to sharing the World Heritage List as an exercise in global representation. Growing North–South tensions within the World Heritage Committee are currently producing yet another shift, towards sharing the right among treaty states to have their candidate sites listed and wishes fulfilled. While formerly an especially cosmopolitan section of normally often nationally oriented heritage experts was in command, the new turn coincides with the ascendancy of career diplomats, that is people with cosmopolitan aspirations who, conversely, strive to serve national interests. They too are cosmopolitan at times, but typically for broader concerns such as world peace or global equity that transcend the focus of the Convention.     

Role of two toxin-producing plankton and their effect on phytoplankton-zooplankton system--a mathematical study supported by experimental findings

Plankton is the basis of the entire aquatic food chain. Phytoplankton, in particular, occupies the first trophic level. Plankton performs services for the Earth: it serves as food for marine life, gives off oxygen and also absorbs half of the carbon dioxide from the Earth's atmosphere. The dynamics of a rapid (or massive) increase or decrease of plankton populations is an important subject in marine plankton ecology and generally termed as a 'bloom'. Harmful algal blooms (HABs) have adverse effects on human health, fishery, tourism, and the environment. In recent years, considerable scientific attention has been given to HABs. Toxic substances released by harmful plankton play an important role in this context. In this paper, a mathematical model consisting of two harmful phytoplankton and zooplankton system will be discussed. The analytical findings will be verified through our experimental observations which were carried out on the eastern part of Bay of Bengal for the last three years.     

Inhibition of biofouling by marine microorganisms and their metabolites

Development of microbial biofilms and the recruitment of propagules on the surfaces of man-made structures in the marine environment cause serious problems for the navies and for marine industries around the world. Current antifouling technology is based on the application of toxic substances that can be harmful to the natural environment. For this reason and the global ban of tributyl tin (TBT), there is a need for the development of "environmentally-friendly" antifoulants. Marine microbes are promising potential sources of non-toxic or less-toxic antifouling compounds as they can produce substances that inhibit not only the attachment and/or growth of microorganisms but also the settlement of invertebrate larvae and macroalgal spores. However, so far only few antilarval settlement compounds have been isolated and identified from bacteria. In this review knowledge about antifouling compounds produced by marine bacteria and diatoms are summarised and evaluated and future research directions are highlighted.