induce liver changes, kidney changes, and depression of the central nervous system. there is an entire spectrum of further health effects such as headache, nausea, fatigue, eye irritation and skin rash for the above cited and other chemicals. at sufficient dosages a large number of soil contaminants can cause death by exposure via direct contact, inhalation or ingestion of contaminants in groundwater contaminated through soil. the scottish government has commissioned the institute of occupational medicine to undertake a review of methods to assess risk to human health from contaminated land. the overall aim of the project is to work up guidance that should be useful to scottish local authorities in assessing whether sites represent a significant possibility of significant harm (sposh) to human health. it is envisaged that the output of the project will be a short document providing high level guidance on health risk assessment with reference to existing published guidance and methodologies that have been identified as being particularly relevant and helpful. the project will examine how policy guidelines have been developed for determining the acceptability of risks to human health and propose an approach for assessing what constitutes unacceptable risk in line with the criteria for sposh as defined in the legislation and the scottish statutory guidance. ecosystem effects this area is contaminated with stagnant water and refuse making the environment unhygienic not unexpectedly, soil contaminants can have significant deleterious consequences for ecosystems. there are radical soil chemistry changes which can arise from the presence of many hazardous chemicals even at low concentration of the contaminant species. these changes can manifest in the alteration of metabolism of endemic microorganisms and arthropods resident in a given soil environment. the result can be virtual eradication of some of the primary food chain, which in turn could have major consequences for predator or consumer species. even if the chemical effect on lower life forms is small, the lower pyramid levels of the food chain may ingest alien chemicals, which normally become more concentrated for each consuming rung of the food chain. many of these effects are now well known, such as the concentration of persistent ddt materials for avian consumers, leading to weakening of egg shells, increased chick mortality and potential extinction of species. effects occur to agricultural lands which have certain types of soil contamination. contaminants typically alter plant metabolism, often causing a reduction in crop yields. this has a secondary effect upon soil conservation, since the languishing crops cannot shield the earth's soil from erosion. some of these chemical contaminants have long half-lives and in other cases derivative chemicals are formed from decay of primary soil contaminants. potential effects of contaminants to soil functions heavy metals and other soil contaminants can adversely affect the activity, species composition and abundance of soil microorganisms, thereby threatening soil functions such as biochemical cycling of carbon and nitrogen. however, soil contaminants can also become less bioavailable by time, and microorganisms and ecosystems can adapt to altered conditions. soil properties such as ph, organic matter content and texture are very important and modify mobility, bioavailability and toxicity of pollutants in contaminated soils. the same amount of contaminant can be toxic in one soil but totally harmless in another soil. this stresses the need for soil-specific risks assessment and measures. cleanup options cleanup or environmental remediation is analyzed by environmental scientists who utilize field measurement of soil chemicals and also apply computer models (gis in environmental contamination) for analyzing transport and fate of soil chemicals. various technologies have been developed for remediation of oil-contaminated soil and sediments there are several principal strategies for remediation: excavate soil and take it to a disposal site away from ready pathways for human or sensitive ecosystem contact. this technique also applies to dredging of bay muds containing toxins. aeration of soils at the contaminated site (with attendant risk of creating air pollution) thermal remediation by introduction of heat to raise subsurface temperatures sufficiently high to volatilize chemical contaminants out of the soil for vapor extraction. technologies include istd, electrical resistance heating (erh), and et-dsp. bioremediation, involving microbial digestion of certain organic chemicals. techniques used in bioremediation include landfarming, biostimulation and bioaugmentating soil biota with commercially available microflora. extraction of groundwater or soil vapor with an active electromechanical system, with subsequent stripping of the contaminants from the extract. containment of the soil contaminants (such as by capping or paving over in place). phytoremediation, or using plants (such as willow) to extract heavy metals. mycoremediation, or using fungus to metabolize contaminants and accumulate heavy metals. remediation of oil contaminated sediments with self-collapsing air microbubbles. surfactant leaching interfacial solar evaporation to extract heavy metal ions from moist soil by country various national standards for concentrations of particular contaminants include the united states epa region 9 preliminary remediation goals (u.s. prgs), the u.s. epa region 3 risk based concentrations (u.s. epa rbcs) and national environment protection council of australia guideline on investigation levels in soil and groundwater. people's republic of china the immense and sustained growth of the people's republic of china since the 1970s has exacted a price from the land in increased soil pollution. the ministry of ecology and environment believes it to be a threat to the environment, to food safety and to sustainable agriculture. according to a scientific sampling, 150 million mu (100,000 square kilometres) of china's cultivated land have been polluted, with contaminated water being used to irrigate a further 32.5 million mu (21,670 square kilometres) and another 2 million mu (1,300 square kilometres) covered or destroyed by solid waste. in total, the area accounts for one-tenth of china's cultivatable land, and is mostly in economically developed areas. an estimated 12 million tonnes of grain are contaminated by heavy metals every year, causing direct losses of 20 billion yuan ($2.57 billion usd). recent survey shows that 19% of the agricultural soils are contaminated which contains heavy metals and metalloids. and the rate of these heavy metals in the soil has been increased dramatically. european union according to the received data from member states, in the european union the number of estimated potential contaminated sites is more than 2.5 million and the identified contaminated sites around 342 thousand. municipal and industrial wastes contribute most to soil contamination (38%), followed by the industrial/commercial sector (34%). mineral oil and heavy metals are the main contaminants contributing around 60% to soil contamination. in terms of budget, the management of contaminated sites is estimated to cost around 6 billion euros (€) annually. united kingdom generic guidance commonly used in the united kingdom are the soil guideline values published by the department for environment, food and rural affairs (defra) and the environment agency. these are screening values that demonstrate the minimal acceptable level of a substance. above this there can be no assurances in terms of significant risk of harm to human health. these have been derived using the contaminated land exposure assessment model (clea uk). certain input parameters such as health criteria values, age and land use are fed into clea uk to obtain a probabilistic output. guidance by the inter departmental committee for the redevelopment of contaminated land (icrcl) has been formally withdrawn by defra, for use as a prescriptive document to determine the potential need for remediation or further assessment. the clea model published by defra and the environment agency (ea) in march 2002 sets a framework for the appropriate assessment of risks to human health from contaminated land, as required by part iia of the environmental protection act 1990. as part of this framework, generic soil guideline values (sgvs) have currently been derived for ten contaminants to be used as "intervention values". these values should not be considered as remedial targets but values above which further detailed assessment should be considered; see dutch standards. three sets of clea sgvs have been produced for three different land uses, namely residential (with and without plant uptake) allotments commercial/industrial it is intended that the sgvs replace the former icrcl values. the clea sgvs relate to assessing chronic (long term) risks to human health and do not apply to the protection of ground workers during construction, or other potential receptors such as groundwater, buildings, plants or other ecosystems. the clea sgvs are not directly applicable to a site completely covered in hardstanding, as there is no direct exposure route to contaminated soils. to date, the first ten of fifty-five contaminant sgvs have been published, for the following: arsenic, cadmium, chromium, lead, inorganic mercury, nickel, selenium ethyl benzene, phenol and toluene. draft sgvs for benzene, naphthalene and xylene have been produced but their publication is on hold. toxicological data (tox) has been published for each of these contaminants as well as for benzopyrene, benzene, dioxins, furans and dioxin-like pcbs, naphthalene, vinyl chloride, 1,1,2,2 tetrachloroethane and 1,1,1,2 tetrachloroethane, 1,1,1 trichloroethane, tetrachloroethene, carbon tetrachloride, 1,2-dichloroethane, trichloroethene and xylene. the sgvs for ethyl benzene, phenol and toluene are dependent on the soil organic matter (som) content (which can be calculated from the total organic carbon (toc) content). as an initial screen the sgvs for 1% som are considered to be appropriate. canada as of february 2021, there are a total of 2,500 plus contaminated sites in canada. one infamous contaminated sited is located near a nickel-copper smelting site in sudbury, ontario. a study investigating the heavy metal pollution in the vicinity of the smelter reveals that elevated levels of nickel and copper were found in the soil; values going as high as 5,104ppm ni, and 2,892 ppm cu within a 1.1 km range of the smelter location. other metals were also found in the soil; such metals include iron, cobalt, and silver. furthermore, upon examining the different vegetation surrounding the smelter it was evident that they too had been affected; the results show that the plants contained nickel, copper and aluminium as a result of soil contamination. india in march 2009, the issue of uranium poisoning in punjab attracted press coverage. it was alleged to be caused by fly ash ponds of thermal power stations, which reportedly lead to severe birth defects in children in the faridkot and bhatinda districts of punjab. the news reports claimed the uranium levels were more than 60 times the maximum safe limit. in 2012, the government of india confirmed that the ground water in malwa belt of punjab has uranium metal that is 50% above the trace limits set by the united nations' world health organization (who). scientific studies, based on over 1000 samples from various sampling points, could not trace the source to fly ash and any sources from thermal power plants or industry as originally alleged. the study also revealed that the uranium concentration in ground water of malwa district is not 60 times the who limits, but only 50% above the who limit in 3 locations. this highest concentration found in samples was less than those found naturally in ground waters currently used for human purposes elsewhere, such as finland. research is underway to identify natural or other sources for the uranium.