Air-soil pathway

Air/Soil Pathway. The original HARM model did not have an air/soil pathway and thus could not account adequately for exposure due to volatization of organics from soil or surface water, or for exposure to contaminated dust. The factors that are considered in scoring this pathway ares... 

Scoring is similar for all pathways, though the appropriate benchmarks will vary. For example, if the pathway is surface or ground water, aquatic benchmarks will be used as well as terrestrial benchmarks. For the air/soil pathway, however, only terrestrial benchmarks are employed. 

System considers surface water and groundwater pathways of exposure in evaluating the potential for adverse effects. Air and soil pathways will be added as will numerous built-in error checking routines. 

HaU BD, Bodaly RA, Fudge RJP, Rudd JWM, Rosenberg DM. 1997. Food as the dominant pathway of methyhnercury uptake by fish. Water Air Soil Pollut 100 13-24. 

Nishimura, H. and M. Kumagai. 1983. Mercury pollution of fishes in Minamata Bay and surrounding water analysis of pathway of mercury. Water Air Soil Pollut. 20 401-411. 

Trace elements on the surfaces of fly ash particles that are accessible to humans through air, soil, water, can affect health in several ways. The pathways by which metals from CCP may cause harm include (1) soil deposition and resulting plant uptake of metals and subsequent movement into the food chain (2) direct ingestion of soil by animals or humans (3) leaching of metals from CCP to water systems and uptake by plants, animals, or humans and (4) inhalation of dust (from soil) or respirable ash particles (Ryan Bryndzia 1997). 

The HRS system is based on risk to health and the environment. The criteria examined include the groundwater migration pathway, surface water migration pathway, soil exposure pathway, and air migration pathway (Hen-drichs, 1991). The ranking attempts to quantify the risk each site poses on a relative scale. Only those sites placed on the NPL will receive CERCLA funds however, regulations in the CERCLA can still be applied to non-NPL sites. 

An ESD is a document that describes the sources, production processes, pathways, and use patterns with the aim of providing a quantified scenario for emissions (or releases) of a chemical from production, formulation, use (industrial use, professional use, private use of chemical substances/prepara-tions), service life (use in articles), and recovery/ disposal into water, air, soil, or solid waste. An ESD should ideally include all the following stages (1) production (2) formulation (3) industrial use (4) professional use (5) private and consumer use (6) service life of product/article (7) recovery and (8) waste disposal (incineration, landfill). ESDs are used in risk assessment of chemicals to establish the conditions of use and releases of the chemicals, and are the basis for estimating the concentration of chemicals in the environment. 

Site-Specific Target Level For a given exposure pathway and contaminant, the SSTL represents a concentration in the affected source medium (soil, groundwater, surface water, or sediment) that is protective of a human or ecological receptor located at a relevant point of exposure (POE). For example, for the human health soil-to-air exposure pathway, the SSTL is the mean concentration in the affected surface soil zone that will prevent unsafe human exposures via vapour or particulate release to air. For each... 

The indirect pathway by which air pollutants interact with plants is through the root system. Deposition of air pollutants on soils and surface waters can cause alteration of the nutrient content of the soil in the vicinity of the plant. This change in soil condition can lead to indirect or secondary effects of air pollutants on vegetation and plants. 

When chemicals are released in the environment, their hazard potential to human or ecological receptors depends upon the extent of contact between the receptors and the chemical. This exposure level is not only influenced by where, when and how much of the chemical is released, but also on its movement and changes in air, water, soil or biota relative to the locations of the receptors. Risk is defined as the probability of some adverse consequence in the health context, or as the probability times the extent of the consequence in the technology context. In this paper we shall examine and discuss how mathematical models are used to generate estimates of risk when more than one of the environmental media must be considered in tracing pathways connecting sources with receptors. The principal objective here is to place in perspective the... 

Environmental exposure (direct). Exposure through air inhalation, soil and dust ingestion, and dermal contact of soil and dust are the principal exposure pathways. Other exposure pathways (e.g., water dermal contact) can be taken into account in some scenarios. Monitoring campaigns or multimedia fate models are used to assess the exposure (see [4]). 

In recent studies, pesticides such as atrazine have been found in precipitation. Therefore volatilization and subsequent transport in the gaseous phase is an important environmental pathway. Vaporization rates of pesticides deposited on surface of soil and plant leaves depend on the physical-chemical properties of the substance. A useful physicochemical criterion is Henry s constant, Ku, which is defined as the equilibrium air-to-water partial pressure ratio of the substance (see Chapter 7). 

Human Health At present, studies on the impact of POPs on human health are very limited in China. Most of the existing literature is focused on dietary studies, as the food chain is considered a major pathway for POPs to effect human health. Information on human health effects such as body burden and metabolism is insufficient and generally extrapolated from modeling data because few doctors have been involved in research on POPs exposures in China. Other exposures through respiration and skin as well as air and soil are seldom studied. 

---