Persistent and bioaccumulative toxics

The hazardous waste identification regulations that define the characteristics of toxicity, ignitability, corrosivity, reactivity, and the tests for these characteristics, differ from state to state. In addition, concentration limits may be set out by a state for selected persistent and bioaccumulative toxic substances that commonly occur in hazardous substances. For example, the California Hazardous Waste Control Act requires the California State Department of Health Services (CDHS) to develop and adopt by regulation criteria and guidelines for the identification of hazardous wastes and extremely hazardous wastes. 

California Administrative Code (1987) Title 22, Section 66699 "Inorganic Persistent and Bioaccumulative Toxic Substances". 

In California Code of Regulations (CCR) Title 22, the State of California imposes additional requirements for the disposal of waste containing 20 inorganic and 18 organic persistent and bioaccumulative toxic substances (CCR, 1991). Hazardous characteristics of waste streams contaminated with these substances are determined as Total Threshold Limit Concentrations (TTLQ and Soluble Threshold Limit Concentrations (STLC), shown in Appendix 4. 

In addition to the LCIA methodology, one may report substances of priority concern, such as those identified as persistent and bioaccumulative toxics (PBTs), as a separate metric. Both approaches are in fact used in companies, as illustrated in the case studies of GlaxoSmithKline (Section 6.1.2) and BASF (Section 6.1.3). 

The remaining chapters in the first section of the book cover the measurement and investigation of the fate and transport of specific chemicals in the soil, water and atmosphere and exchange among these media. Chapter 3 by West and Wilson reviews subsurface natural attenuation of contaminants. Chapters 4, 5, and 6 by Stone et ai, Soderstrom et ai, and Butler and Hayes, respectively, all relate to the movement and fate of organic chemicals in soils and sediments, while Chaper 9 by Pedersen and Suffet and Chapter 10 by Salmun and Farhan focus on runoff from the terrestrial environment to nearby waters. These last two chapters illustrate the need to understand the complexities of non-point source pollutant inputs. Recent books have also focused on similar topics for persistent and bioaccumulative toxics (PBTs) (41,42). 

Several hundred-pesticide compounds of diverse chemical structures are widely used in the United States and Europe for agricultural and non-agricultural purposes (Fig. 10). Some are substitutes for organochlorines, which were banned due to their toxicity, persistence, and bioaccumulation in environmental matrices. According to a report published by the US-EPA, a total of 500,000 tons of pesticides was used in 1985 [144, 145, 148]. As far as specific pesticides are concerned, worldwide consumption of Malathion and Atrazine in 1980 amounted to 24,000 and 90,000 tons, respectively [149,150]. In the Mediterranean countries, 2100 tons of Malathion (active ingredient) were sprayed during the same period compared to 9700 tons in Asia [150]. 

Chlorinated micropoUutants are harmful for man and environment due to their toxicity, persistence, and bioaccumulation. Persistent compounds are very stable and difficult to get metabolized and mineralized by biological and chemical processes in the environment, and as a result, they have become ubiquitous in water, sediments, and the atmosphere bioaccumulation is the result of the lipophilicity of these compounds. Polychlorinated dibenzodioxins and -furans (PCDD/F) are not produced purposely like many of other chlorinated technical products, such as chlorinated biocides DDT, lindane, and toxaphene. The production and use of persistent organic pollutants (POPs), the dirty dozen has now been banned worldwide by the Stockholm protocol. It should be mentioned that about 3000 halogenated products have now been isolated as natural products in plants, microorganisms, and animals," but the total amount of these products is much smaller compared to xenobiotics. 

There are occasional outbursts of skepticism about the value of the risk assessment approach. Some argue its full use is overly burdensome, that the only real need is to identify toxic chemicals and then eliminate them or reduce their presence. Perhaps this approach is appropriate for a few chemicals that exhibit extremely high toxicity or that are excessively persistent and bioaccumulate in an environment, and for which there are reasonably good substitutes available. But as a general approach, it ignores the elementary principle that all chemicals will... 

The Bromine Industry in particular, points out that non-brominated chemical flame retardants may be very hazardous and that the phase-out of BFRs may not be safe. The non-brominated alternatives listed in the above case studies are likely to be safer if they exhibit less persistence and bioaccumulation in living systems, but some do possess significant toxicity. In the last few years, some agencies have therefore investigated the relative merits of alternatives to BFRs. 

Pesticides and Bioaccumulators - Pesticides include the broad categories of insecticides, fungicides rodenticides, and herbicides. Insecticides in common use fall into three categories. The chloroinsecticides have chlorine in their structure. They are less soluble than the other insecticide forms and much less biodegradable (i.e., more persistent). While they are less acutely toxic, several have been identified as potential carcinogens. Carbamatea are a relatively new form of pesticide. They are less persistent and less toxic than chioroinsecticides, but some are also... 

Other environmental impacts can be calculated similarly by using the appropriate equivalency factor. Impacts of human toxicity and ecotoxicity are, for example, determined by factors such as toxicity data (for humans, resp. various nonhuman life forms), persistence, and bioaccumulation. Equivalency factors for... 

Based on high toxicity, persistence, and bioaccumulation potential coupled with high usage and detection in environmental compartments substances whose EQSs appear overly conservative (exceeded at control sites) are targeted for reevaluation... 

A chemical structure can be used to predict its interaction with environmental media and biological systems. Even simple physical chemistry can accurately predict the persistent and bioaccumulative properties of certain types of chemical [86]. Equally, certain hazardous properties can be qualitatively predicted by comparing a molecular structure with similar substances with known hazard profiles [87], Many developments have been achieved using actual computational techniques (e.g., QSAR) to quantitatively evaluate the toxic properties of substances, particularly pharmaceuticals (see [88, 89]). 

OSHA PB PBB PBT PEC penta-BDE PFOS PNEC POP PPE PPORD PRODUCE European Agency for Safety and Health at Work Persistent and bioaccumulating Polybromobiphenyl(s) Persistent, bioaccumulative and toxic Predicted environmental concentration Pentabromodiphenyl ether Perfluorooctane sulfonate Predicted no-effect concentration Persistent organic pollutant Personal protective equipment Process/product-oriented research and development Piloting REACH on downstream use communication in Europe... 

Environment Canada (1995) Toxic Substances Management Policy - Persistence and Bioaccumulation. Environment Canada, Ottawa, Canada... 

Apart from mercury and cadmium. List I refers to families or groups of substances rather than to individual substances identified on the basis of toxicity, persistence, and bioaccumulation. 

It will therefore be necessary to choose certain individual substances from among the families or groups in order to study them and, if appropriate, prepare proposals for the Council. The Directive states that these substances must be selected mainly on the basis of their toxicity, persistence and bioaccumulation. 

The method used is probably one of the best possible, but the mathematical model can only perform a rough simulation of the natural environment. It has also been necessary to make a number of estimates owing to the lack of exact data on the quantities, toxicity, persistence and bioaccumulation of certain substances. 

Pollutants/Toxic Dispersion Persistent and Bioaccumulative Total (mass persistent + bioaccumulative) (kg) Mass product (kg) Human Health Total (mass of material [for all materials]) (kg) Permissable exposure limit (ACGIH) (ppm) kg/kg... 

The dioxins, especially 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are extremely toxic and exert effects at submicrogram levels. They are also very lipophilic and persistent and bioaccumulate and biomagnify very effectively. Toxic action is... 

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. 

Muir DCG, Bennie D, Teixeira C, Fisk AT, Tomy GT, Stem GA, Whittle M (2001) Short chain chlorinated paraffins are they persistent and bioaccumulative In Lipnick R, Jansson B, Mackay D, Patreas M (eds) Persistent, bioaccumulative and toxic substances, vol 2. ACS Books, Washington, DC, pp 184—202... 

Environmental effects can be examined using studies on the toxicity, persistence and bioaccumulation for the substance in representative studies in individual species, in microcosms and in observations during field trials. Modelling of the transport and fate of the substance is also helpful. Surveys assist in providing baseline data on habitats and communities present. One aim of this exercise will be to determine how tolerant the environment in question will be at accepting the substance before some form of environmental degradation occurs. 

Table 1 summarizes the threshold values used by the Stockholm Convention and other government institutions to classify chemicals as P, B, and/orT. "Threshold values"are the cutoff points used for a) determining whether a chemical poses a certain type of hazard (such as, P or B orT) and b) assigning levels of concern (typically high, moderate, or low) for a particular hazard (such as P). On the x-axis ofTable 1 are the governmental institutions and on the y-axis are the hazards (P, B, and T) as well as levels of concern associated with persistence and bioaccumulation (very high, high, moderate, or low). In Table 1, "Toxicity -T"is not divided into levels of concern because only one of the governmental organizations has done that—the US EPA. The criteria used by the US EPA to divide toxicological concerns into high, moderate, and low are discussed below in section 4.2.

Several hundred-pesticide compounds of diverse chemical structures are widely used in the United States and Europe for agricultural and non-agricultural purposes, generating large amounts of solid waste materials. Some are substitutes for organochlorines, which were banned due to their toxicity, persistence, and bioaccumulation in environmental matrices. Chemical structures of various pesticides are shown in Fig. 3. 

Mercury is identified as the toxic of greatest concern in all the air toxics emitted from power plants due to its persistence and bioaccumulation in the foods and environment (Senior et al., 2000). It generally occurs in coal in association with sulfide minerals (FeS2 and HgS), it may also be organically bound to the coal macerals (Pavlish et al., 2003 Sondreal et al., 2004 Kolker et al., 2006). Mercury concentration in coals is about 0.1-0.15 g/ton and it passes to the flue gas during the combustion... 

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