Persistent substance

Until recently, the NRA has not participated during the approval process in assessing the potential environmental impact of pesticides. However, the NRA does supply monitoring data to MAFF and HSE for pesticide reviews. These occur once a pesticide has been approved for use for a certain length of time, or when further information is needed on an approved pesticide. In supplying these data, the NRA comments on any areas of concern. This contributed to the 1993 ban on the use of atrazine and simazine on non-cropped land. In January 1995 the NRA s National Centre for Toxic and Persistent Substances (TAPS) was made advisor to the DoF, on the potential impact on the aquatic environment of... 

A.D. Barnden, National Rivers Authority, National Centre for Toxic and Persistent Substances, Kingfisher House, Goldhay Way, Orton Goldhay, Peterborough PE2 5ZR, UK... 

Persistent substances produced by society e.g. DDT, CFCs) must not systematically increase. 

CW agents can be classified in many different ways. There are, for example, volatile substances, which mainly contaminate the air, or persistent substances, which are involatile and therefore mainly cover surfaces. 

VX (O-ethyl S-diisopropylaminomethyl methylphosphonothiolate) is a persistent substance with the ability to remain on material, terrain, and equipment for long periods of time. Exposure is mainly through the skin but also by inhalation of VX as a gas or aerosol. 

The substitution of chemical solvents by water in paint and coating systems and also in cleaning processes creates complex evaluation issues, as the number of the various chemical components contained in the corresponding products generally increases. In addition, the release of persistent substances into the aquatic environment tends to be favoured by this. This therefore raises the question for assessing two suitable strategies containment of known hazardous substances in closed systems or substitution of the mobile solvent by complex water-based systems that are scarcely evaluable from a toxicological aspect. 

To finalize this review, we have to consider that the accumulation of toxic and persistent substances in the marine environment continuously... 

The structural features associated with degradable and persistent substances could... 

At the present time, a geologic repository is the intended disposal system for most radioactive waste that is not acceptable for nearsurface disposal. Alternatives to near-surface disposal facilities have not been considered for hazardous chemical waste that contains unusually high concentrations of persistent substances (e.g., heavy metals). 

A persistent substance undergoes very slow rates of degradation in environmental media and/or metabolism in biological systems. The term therefore refers to the ability of a substance to remain unchanged in the wider environment. 

Measures such as these, which give manufacturers direct fiscal responsibility for managing the waste generated by their products, may well create an added incentive for removing hazardous and persistent substances from the products in question, as well as encourage ingenious reuse strategies that can turn potential wastes into raw materials for future products. Ericsson Electronics, for example, has already communicated to vendors the names of chemicals it will not accept as constituents of the products it buys (Fishbein, 2002). 

An example may help to understand this. We may have five objects (A, B, C, D, E characterized by e.g. their environmental persistence P and by their ability to bioaccumulate B . As often is the case both attributes do not behave parallel, i.e. it is not automatically given that a persistent substance also is the most bioaccumulating. 

SCCPs are persistent and bioaccumulative, and thus concentrations in the environment and biota are expected to increase with continued release to the environment. Standard risk assessment methods comparing effect levels to environmental concentrations may underestimate the risk of persistent and bioaccumulative substances, such as SCCPs. Persistent substances can take decades to reach a maximum steady state concentration in the environment, resulting in an underestimation of the potential exposure to these compounds if steady-state has not been achieved, and releases into the environment continue. Similarly, it can take a long time for persistent and bioaccumulative substances to reach a maximum steady-state concentration within an organism this is supported by the observations of Sochova et al., [62] who noted an increase in toxicity of SCCPs for longer exposure duration with nematodes. The durations of standard toxicity tests may be insufficient to achieve the maximum tissue concentration, resulting in an underestimation of the effect threshold. 

The substances have to have such characteristics that allow them to move relatively easily among different environmental compartments - air, water and soil. These compounds are not polar i.e. they are sparingly soluble in water and have low to intermediate volatility. Substances with such characteristics cannot be present exclusively neither in water nor in air, i.e. they are not exclusively water or air pollutants. Because of their properties to be presented simultaneously in different environmental media they are often referred to as intermedia pollutants. The Long Range Transport (LRT) of persistent substances could be realized in different ways ... 

Pesticides containing metals and chlorinated hydrocarbons such as DDT and aldrin belong to the highly persistent substances persistent ones are urea and triazin pesticides medium persistent ones include amides and derivatives of benzoic acid less persistent pesticides are based on phenoxy-... 

Ideally, sustainable materials should match or exceed the physical and mechanical properties of the replaced polymer, be available at a competitive price, be issued from renewable resources, and be environmentally friendly, i.e., entirely recyclable without the release of hazardous and persistent substances [45, 46]. 

Environment Environmentally hazardous substance. Very persistent substance. Will bioaccumulate and biomagnify in the food chain. 

The mechanism by which pesticides exert their toxic effects on mammals has been characterized for only a few groups of compounds [17,18]. For example, the mechanism for organophosphorus and carbamate insecticides involves inhibition of cholinesterase also, nitrophenols and higher chlorinated phenols are inhibitors for oxidative phosphorylation [10]. Fat-soluble substances (e.g., organochlorines such as DDT, HCH, and other persistent substances) accumulate in the body and, when stored in fatty tissues, cannot be... 

The problem was that a benign, persistent substance, such as titanium dioxide, would score at least a 5 and in most cases a 6. This is because these benign substances persist and received a maximum score for persistence, together with the minimum scores for bioaccumulation and toxicity (which also contain a persistence sub-parameter). A minimum score in each category was still a score, not a zero. 

Table 12.25 briefly summarises the basic criteria that must be met by contaminants to be classified as POPs. Table 12.26 lists the original POPs included in the Convention, along with other high-risk pollutants, which were included in 2009 in the light of the (then) latest information. Also linked with efforts to restrict the movement of persistent substances in the environment is the implementation of the new EU policy REACH (Registration, Evaluation and Authorisation of CHemicals), which represents a new chemical control system to ensure that, by 2020 at the latest, only compounds with known properties are used in a manner that protects the environment and human health. 

Lammel, G., Klopffer, W., Semeena, V.S., Schmidt, E., and Leip, A. 2007. Multicompart-mental fate of persistent substances Comparison of predictions from mulimedia box models and a multicompartment chemistry—atmospheric transport model. Environ. Sci. Pollution Res. 14 153-165. 

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