Environmental risks of chemicals and genetically modified organisms: a comparison. Part II: Sustainability and precaution in risk assessment and risk management

The principles of precaution and sustainability require more consideration in the assessment of environmental risks posed by chemicals and genetically modified organisms. Instead of applying risk reduction measures when there are serious indications for damage, full scientific certainty is often waited for before taking action. The precautionary principle particularly should be applied in those cases in which the extent and probability of damage are uncertain, e.g. in the case of persistent chemicals which are additionally bioaccumulative or highly mobile. Based on these principles, environmental action targets for risks associated with GMOs and chemicals can be developed. Risk management not only includes statutory measures but also instruments designed to influence behaviour indirectly are important to achieve the goals. Particularly for risks of GMOs which provoke fear, risk communication is important. Some rules to which attention should be paid in communication with the public are presented.     

The precautionary principle and ecological hazards of genetically modified organisms

This paper makes three points relevant to the application of the precautionary principle to the regulation of GMOs. i) The unavoidable arbitrariness in the application of the precautionary principle reflects a deeper epistemological problem affecting scientific analyses of sustainability. This requires understanding the difference between the concepts of "risk", "uncertainty" and "ignorance". ii) When dealing with evolutionary processes it is impossible to ban uncertainty and ignorance from scientific models. Hence, traditional risk analysis (probability distributions and exact numerical models) becomes powerless. Other forms of scientific knowledge (general principles or metaphors) may be useful alternatives. iii) The existence of ecological hazards per se should not be used as a reason to stop innovations altogether. However, the precautionary principle entails that scientists move away from the concept of "substantive rationality" (trying to indicate to society optimal solutions) to that of "procedural rationality" (trying to help society to find "satisficing" solutions).     

Information system for monitoring environmental impacts of genetically modified organisms

Background, aim and scope  

European legislation stipulates that genetically modified organisms (GMO) have to be monitored to identify potential adverse environmental effects. A wealth of different types of monitoring data from various sources including existing environmental monitoring programmes is expected to accumulate. This requires an information system to efficiently structure, process and evaluate the monitoring data.     

Environmental risk evaluation of chemicals: achievements of the project and seeds for future--development of metrics for evaluating risks

Achievements of the research project entitled "Establishment of a scientific framework for the management of toxicity of chemicals based on environmental risk-benefit analysis" supported by the JST were introduced and reviewed, focusing on the development of the methodology for estimating risks; human health risks and ecological risks. The usefulness of loss of life expectancy as a metric for evaluating cancer and noncancer risks was demonstrated. To evaluate ecological risks, three metrics, 1/T, logT and T, developed based on the mean extinction time (T) of species were proposed. Then, their implication and feasibility were examined in terms of what ecological system should be conserved and how easily people can understand the implications of metrics. Protocols for estimating human health risks and ecological risks are illustrated.     

Bioaccumulation of hydrophobic organic chemicals by aquatic organisms: a workshop summary

Traditionally, regulatory approaches to the bioaccumulation of hydrophobic organic chemicals (HOCs) have emphasized the direct accumulation of these chemicals from solution across biological membranes, leading to the development of the bioconcentration factor as a measure of direct uptake of freely dissolved HOCs. However, an often larger fraction of the total amount of many HOCs in the water column is not freely dissolved, but is partitioned among suspended sediments and particulate matter in the water column. Partitioned HOCs are available for accumulation by organisms ingesting the contaminated particulate matter. The net accumulation of HOCs from water through consumption and direct uptake of dissolved HOC is termed bioaccumulation, quantified using a bioaccumulation factor. In order to develop recommendations designed to close the gap between current knowledge concerning bioaccumulation and regulations, the Institute of Evaluating Health Risks organized a working conference, 'The Bioaccumulation of Hydrophobic Organic Chemicals by Aquatic Organisms'. This paper reflects the view of workshop participants that the bioaccumulation paradigm can be used in a number of practical applications.     

Environmental Hazard- Assessment of chemicals and products

Part II: Persistence and Degradability of Organic Chemicals The criteria “Persistence” and “Degradability” are defined and explained, starting from the “functional” definition of the environment. In this definition, theenvironment is the counterpart of thetechnosphere, which consists of all processes controlled by man. A substance is persistent if there are no sinks (degradation processes). It is shown that persistence is the central and most important critérium of environmental hazard assessment of organic chemicals. It follows that all substances released into the environment should be degradable, preferentially into small inorganic molecules (mineralization). As examples for persistent substances, the polychlorinated biphenyls (PCB), the chlorofluorohydrocarbons (CFC), bis (2-ethylhexyl) phthalate (DEHP), and 2,3,7,8-tetrachloro-dibenzo-dioxin (TCDD) are discussed. Finally, an attempt to quantify persistence is made.     

Amphibians and agricultural chemicals: Review of the risks in a complex environment

Agricultural landscapes, although often highly altered in nature, provide habitat for many species of amphibian. However, the persistence and health of amphibian populations are likely to be compromised by the escalating use of pesticides and other agricultural chemicals. This review examines some of the issues relating to exposure of amphibian populations to these chemicals and places emphasis on mechanisms of toxicity. Several mechanisms are highlighted, including those that may disrupt thyroid activity, retinoid pathways, and sexual differentiation. Special emphasis is also placed on the various interactions that may occur between different agro-chemicals and between chemicals and other environmental factors. We also examine the indirect effects on amphibian populations that occur when their surrounding pond communities are altered by chemicals.     

Quantifying risks of toxic chemicals to aquatic populations and ecosystems

The objectives of regulatory practice have evolved from eliminating all risks of pesticides and toxic chemicals to the environment to reducing risks to acceptable levels. This change in philosophy requires the development of methods for quantifying the risks of toxicant exposure to the exposed biota. Ecological risk assessment models that are comparable those used in human health risk assessment have been developed using methods drawn from ecotoxicology, ecology, statistics, and mathematical modeling. Initial applications have shown that the regulation of pesticides and toxic chemicals can be substantially improved through the use of ecological risk assessment.     

Dynamics of trace metals in organisms and ecosystems: prediction of metal bioconcentration in different organisms and estimation of exposure risks

Metal ions interact with biological materials and their decomposition products by ligation (coordination complex-formation with certain moieties containing O, N, S, etc.). The extent of this interaction depends on the identities of both ligand and metal ion and can be described by some equation derived from perturbation theory. Uptake of metal ions - including highly toxic ones - from soils is controlled by a competition between root exudate components and soil organic matter (SOM) for the ions. SOM consists of a variety of potential ligands which evolve during humification towards more efficient binding (retention) of metals such as Cu, Ni, Cr but also of toxicants like U, Cd. The actual way of interaction can be inferred from stoichiometry of the involved compounds and the C/N ratio in the soil, providing predictions as to which metals will be most efficiently shuttled into green plants or fungi, respectively. The latter, selective process is crucial for closing nutrient cycles and sensitively depends on C/N ratio and the extent of "forcing" by onfalling leaf or needle litter. Therefore, analytical data on the soil can be used to predict possible risks of exposition to toxic metals also for human consumption of plant parts.     

Environmental risk assessment of existing chemicals

Most of the existing chemicals of high priority have been released into the environment for many years. Risk assessments for existing chemicals are now conducted within the framework of the German Existing Chemicals Program and by the EC Regulation on Existing Substances. The environmental assessment of a chemical involves:

1. exposure assessment leading to the derivation of a predicted environmental concentration (PEC) of a chemical from releases due to its production, processing, use, and disposal. The calculation of a PEC takes into account the dispersion of a chemical into different environmental compartments, elimination and dilution processes, as well as degradation. Monitoring data are also considered.
2. effects assessment. Data obtained from acute or long-term toxicity tests are used for extrapolation on environmental conditions. In order to calculate the concentration with expectedly no adverse effect on organisms (Predicted No Effect Concentration, PNEC) the effect values are divided by an assessment factor. This assessment factor depends on the quantity and quality of toxicity data available.

In the last step of the initial risk assessment, the measured or estimated PEC is compared with the PNEC. This “risk characterization” is conducted for each compartment separately (water, sediment, soil, and atmosphere). In case PEC > PNEC an attempt should be made to revise data of exposure and/or effects to conduct a refined risk characterization. In case PEC is again larger than PNEC risk reduction measures have to be considered.     

Environmental chemicals and biomembranes 1. Nitrilotriacetic acid

Nitrilotriacetic acid (NTA) is readily taken up by yeast cells through simple diffusion and is metabolized. Concentrations of NTA in the millimolar range do not interfere with various membrane functions of yeast and bacteria.     

Environmental and biological monitoring of endocrine disrupting chemicals.

Trends toward an increase of adverse health effects on reproductive organs have been reviewed. An urgent need has been recognised to establish validated in vivo and in vitro screening assays to test for hormonal activities of chemicals. Relevant existing OECD guidelines have been reviewed and enhancements of some of these have been identified, mainly to test for estrogenic and androgenic activity of chemicals. The problems connected to monitoring activities are outlined, particularly for ambient and biological monitoring. Indeed, the problem of assessing human exposure to endocrine disrupting chemicals through environmental chemical analysis tends to a very high level of complexity. This has been illustrated through the example of one single subclass of endocrine disrupting compounds (EDCs), the organohalogen compounds. Valid biological markers are also needed to be effectively used in epidemiological studies and risk assessment. A multidisciplinary approach and the collaboration among experts in the field of clinical biochemistry, toxicology, and epidemiology is required.     

Environmental toxicology and associated human health risks

Environmental Science and Pollution Research -     

A comparison of octanol-water partitioning between organic chemicals and their metabolites in mammals

Bioaccumulation models take various elimination and uptake processes into account, estimating rates from chemical lipophilicity, expressed as the octanol-water partition ratio (K_ow). Here, we focussed on metabolism, which transforms parent compounds into usually more polar metabolites, thus enhancing elimination. The aim of this study was to quantify the change in lipophilicity of relevant organic pollutants undergoing various biotransformation reactions in mammals. We considered oxidation reactions catalyzed by three enzyme groups: cytochrome P450 (CYP), alcohol dehydrogenase (ADH), and aldehyde dehydrogenase (ALDH). Estimated log K_ow values of a selected dataset of parent compounds were compared with the log K_ow of their first metabolites. The log K_ow decreased by a factor that varies between 0 and −2, depending on the metabolic pathway. For reactions mediated by CYP, the decrease in K_ow was one order of magnitude for hydroxylated and epoxidated compounds and two orders of magnitude for dihydroxylated and sulphoxidated xenobiotics. On the other hand, no significant change in lipophilicity was observed for compounds N-hydroxylated by CYP and for alcohols and aldehydes metabolized by ADH and ALDH. These trends could be anticipated by the calculus method of log K_ow. Yet, they were validated using experimental log K_ow values, when available. These relationships estimate the extent to which the elimination of pollutants is increased by biotransformation. Thus, the quantification of the K_ow reduction can be considered as a first necessary step in an alternative approach to anticipate biotransformation rates, which are hard to estimate with existing methods.     

Seed bank persistence of genetically modified canola in California

Introduction

Canola, which is genetically modified (GM) for tolerance to glyphosate, has the potential to become established as a new glyphosate resistant weed, thus reducing the effectiveness of glyphosate.

Methods

Volunteer from dormant canola seeds produced thousands of plants per hectare in the fourth year (2011) following a 2007 crop harvest. This occurred with no additional canola seed production since the 2007 harvest.

Results

Volunteer plants following harvests of annual crops are typically only a problem for the first year after harvest. In California, glyphosate is the core herbicide on over a million hectares of high value row, tree, and vine crops and new glyphosate resistant weeds reduce the effectiveness of glyphosate.

Conclusions

The combination of dormant seed and herbicide resistance makes GM glyphosate-resistant canola a new and difficult California weed which was first observed in the winter of 2009.     

Monitoring of genetically modified Escherichia coli in laboratory wastewater

Containment of genetically modified (GM) microorganisms such as Escherichia coli is a legal requirement to protect the environment from an unintended release and to avoid horizontal gene transfer (HGT) of recombinant DNA to native bacteria. In this study, we sampled the laboratory wastewater (LWW) at a large Swiss university from three sources over 2 years and cultured ampicillin-resistant, presumptive GM E. coli. From a total of 285 samples, 127 contained presumptive GM E. coli (45%) at a mean concentration of 2.8 × 10² CFU/ml. Plasmid DNA of 11 unique clones was partially or entirely sequenced. All consisted of cloning vectors harboring research-specific inserts. To estimate the chance of HGT between GM E. coli and native bacteria in LWW, we identified taxa representative for the bacterial community in LWW using 16S rRNA amplicon sequencing and measured conjugation frequencies of E. coli with five LWW isolates. At optimal conjugation conditions, frequencies were between 3.4 × 10⁻³ and 2.4 × 10⁻⁵. Given the absence of transferable broad-host range plasmids and suboptimal conjugation conditions in the LWW system, we conclude that the chance of HGT is relatively low. Still, this study shows that the implementation of robust containment measures is key to avoid the escape of GM microorganisms.

     

Dispersal and persistence of genetically modified oilseed rape around Japanese harbors

Background, aim, and scope

The possibility of gene transfer from genetically modified oilseed rape (OSR) to its cultivated or wild relatives is of concern since its commercial cultivation, because of its potential weediness and impact on the environment. Introgression of modified genes can affect conservation of agricultural crops, because there are many cultivars and wild Brassicaceae that may cross with genetically modified OSR (Brassica napus) in Japan. Japan imports more than 2 million tons of OSR a year from Canada and other countries. Since volunteers of GM OSR were found around harbors in 2004, a lot of feral GM OSR was discovered in Japan. To consider the way how to keep domestic Brassicaceae from GM contamination, we surveyed and analyzed the dispersal and persistence of GM OSR around Japanese harbors. We present the cause and abundance of GM OSR in Japan by this paper.

Materials and methods

Survey of the feral OSR was performed several times a year at different seasons when domestic OSR either grows or does not around port areas. Detection of herbicide tolerance in feral B. napus was done by test papers that cross react with the modified gene product. Two kinds of herbicide tolerance (glyphosate and glufosinate) were tested.

Results

The feral B. napus were discovered around all 13 harbors that import rapeseeds from foreign countries. Genetically modified, herbicide-tolerant OSR were frequently found in the surveyed populations. Two kinds of herbicide-tolerant OSR (glyphosate- and glufosinate-tolerant) were discovered in a natural condition 40 km from port to an oil factory where 60,000 tons of OSR seed are processed a year. The cause of voluntary growth of OSR is seed spillage during transportation by trucks from harbors to oil factories and other processing facilities. Some of the feral OSR growing along the roadsides of transport paths exhibited perennial growth spilling their seeds around the places. Alteration of the generation of feral GM OSR was discovered for the first time in Japan as a result of this study. We studied the yearly change of feral OSR abundances focusing on Yokkaichi port over the 4 years since 2004. The rate of GM OSR increases year to year, and reaches nearly 90% in 2008.

Discussion

The possibility and consequences of gene transfer from the genetically modified OSR to domestic species (B. rapa and B. juncea) were discussed in relation to impact on domestic agriculture and on environments. Evolutional meaning of the gene transfer was also discussed with respect to the gene construct of GM OSR. This study shows the importance of another pathway of modified gene transfer to non-GM relative species by seed transportation in addition to pollen transfer from commercial cultivation of genetically modified OSR.

Conclusions and recommendations

We identified unintended dispersal and persistence of GM OSR around Japanese harbors that import OSR from Canada and other countries. Both glyphosate- and glufosinate-tolerant feral B. napus were discovered. The cause of volunteer OSR is spillage of the seeds during transportation by truck to oil factory. The feral GM OSR sometimes showed perennial growth in Japanese phonological conditions which are not observed for domestic Brassicaceae. In addition, we confirmed an alteration of generations by feral GM OSR in Japan. The possibility of cross pollination and GM gene introgression to domestic varieties can occur in these environments. To improve the situation, each responsible organization, company, administration, or government should establish measures how to stop the dispersal and persistence of GM OSR in nature. Also, the GM plant developers are responsible for revising this situation.     

A comparison of acute toxicity of biodiesel, biodiesel blends, and diesel on aquatic organisms

The increased demand of alternative energy sources has created interest in biodiesel and biodiesel blends; biodiesel is promoted as a diesel substitute that is safer, produces less harmful combustion emissions, and biodegrades more easily. Like diesel spills, biodiesel can have deleterious effects on the aquatic environments. The effect of neat biodiesel, biodiesel blends, and diesel on Oncorhynchus mykiss and Daphnia magna was evaluated using acute toxicity testing. Static nonrenewal bioassays of freshwater organisms containing B100, B50, B20, B5, and conventional diesel fuel were used to compare the acute effects of biodiesel to diesel. Mortality was the significant end point measured in this study; percent mortality and lethal concentration (LC50) at different exposure times were determined from the acute toxicity tests performed. Trials were considered valid if the controls exhibited > 90% survival. Based on percentage of mortality and LC50 values, a toxicity ranking of fuels was developed.     

改性生物质炭与聚磷菌联合去除废水中的磷

为了探索改性生物质炭与聚磷菌联合去除废水中磷的效果,将铁改性生物质炭以及聚磷菌投加入序批式废水处理装置中,间隙进水,间隔一定时间测定水中磷浓度随时间变化,并探讨不同水力停留时间、进水COD浓度以及初始磷浓度对联合除磷的影响。研究结果表明,铁改性生物质炭和聚磷菌联用能高效去除废水中磷,在30℃、水力停留时间6 h、COD浓度280 mg·L-1、初始磷浓度5 mg·L-1并且持续曝气条件下,联合除磷效果最优,其磷去除率可达97.94% 。铁改性生物质炭和聚磷菌联合能有效去除废水中磷,为废水除磷提供了新技术。     

Statistical evaluation of chronic toxicity data on aquatic organisms for the hazard identification: the chemicals toxicity distribution approach

Presently, in the Globally Harmonised System of Classification and Labelling of Chemicals the classification of substances for long-term effects to aquatic life is based on acute toxicity in combination with degradation and/or bioaccumulation potential. Recently an OECD Working Group was created to develop the classification scheme to accommodate chronic toxicity data related to aquatic organisms for assigning a chronic hazard category. This study focuses on a new approach for setting chronic toxicity cut-off values based on Chemicals Toxicity Distributions (CTDs). A CTD is obtained through statistical fitting of the data used by regulatory bodies for setting hazard-based classifications. The CTDs were made using the lowest aquatic NOEC value of each chemical. A review of different toxicological sources reporting acute aquatic toxicities was carried out. Initially, the data were arranged according to the specific source and distributions for key taxonomic groups (i.e. fishes, crustaceans and algae) were evaluated separately. In most cases, no significant departures from normality were observed. Thereafter, a compiled database containing >900 values was developed and the CTDs were constructed for each taxonomic group. Significant deviation from normality (P < 0.05) was observed in the fishes and crustaceans' CTDs. However, this deviation was apparently produced by the presence of only seven values with NOECs <1 x 10(-5) mg l(-1), while high correlation between the data and the normal scores (r-values>or= 0.989) indicated that the data were samples from normal distributions. From these observations, potential cut-off values would allow quantitative estimations of the percentage of chemicals falling into each specific category. This approach results in a simple classification hazard scheme where most chemicals are covered in one of the categories, allowing a clear distribution of the chemicals among three categories for chronic toxicity.