OBJETIVOS

In Australia, independent regulations have been developed in New South Wales (NSW EPA, 2000), Queensland (Qld EPA, 2002), South Australia (S.A. EPA, 2006), Tasmania (Anonymous, 1999), Victoria (EPA Victoria, 2004), Western Australia (Anonymous, 2002) for a range of metals, organic compounds and treatment requirements for final pathogen content. Australian guidelines have also been developed by the National Water Quality Management Strategy and are presented in Table 1-3.

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Table 1-3 Australian ‘National Water Quality Management Strategy’ chemical contamination guidelines (mg kg^-1 dw) (NRMMC, 2004)

Constituent Unrestricted use Contaminant limit

Metals Arsenic 20 60

Cadmium 1 20

Chromium (III) 100-400 500-3000

Copper 100 2500

Lead 150-300 420

Mercury 1 15

Nickel 60 270

Selenium 3 50

Zinc 200 2500

Organic Compounds ΣDDT 0.5 1

Other OCPs 0.02-0.05 0.5

PCBs 0.05-0.3 0.5

Metal contamination has been the major focus of Australian regulators (NRMMC, 2004). Australian scientists have recently completed a large volume of experimental work (National Biosolids Research Program) that has focussed on metal

contamination soils and plant toxicity, which may change the way that Australia regulates biosolids with respect to metals. The US EPA developed chemical pollutant limits based upon sewage-sludge surveys and risk assessments, which were used to identify and characterize risks from chemical pollutants in sewage sludge (National Research Council, 2002). The risk assessments considered a variety of pathways by which humans, animals, plants, and soil organisms could be exposed to pollutants, and pollutant concentration limits were developed for ten inorganic chemicals

(arsenic, cadmium, chromium, copper, lead mercury, molybdenum, nickel, selenium, and zinc), using the most limiting exposure pathway (National Research Council, 2002).

There are currently no Australian guidelines that propose numerical limits on the concentration of dioxin-like compounds within soils (NEPC, 1999). Only EPA Victoria has proposed an “investigation limit” of 50 ng TEQ kg^-1 dw (unitless) (EPA Victoria, 2004). Germany has a long-term objective to have dioxin-like compounds soil concentrations below 5 ng I-TEQ kg^-1 dw. Cultivation of foodstuffs is not restricted in the case where the soil contains 5 – 40 ng I-TEQ kg^-1 but is limited to plants with minimum dioxin-like compounds transfer (Muller et al., 1993). The New

Zealand soil threshold of 10 ng I-TEQ kg^-1 dw for agricultural soil is based upon protection of human health and incorporating the WHO tolerable daily intake for PCDD/F of 10 pg kg^-1 body weight per day (Muller et al., 2004). Several European countries regulate permissible concentrations of dioxin-like compounds in biosolids and the of 100 WHO98 TEQ was the last recommendation by the European Union (European Union, 2001). The US EPA had proposed a numerical limit of 300 ng I-TEQ kg-1 dw but decided against implementing this contaminant limit (U.S. EPA, 2003).

There are no contaminant limits domestically or internationally for PBDEs or PBBs in biosolids or soil.

Internationally, few countries regulate permissible levels organic pollutants in biosolids, and other than Australia, no country regulates the classic organochlorine pesticides (OCPs). Other countries do regulate permissible levels of PCBs in sludge.

The European Union proposed a limit of 0.8 mg kg^-1 dw (European Union, 2001), and some European countries have more stringent regulations; Sweden, Austria and Germany have contaminant limits of 0.4, 0.2 and 0.2 mg kg^-1 dw respectively (European Commission, 2001). In Australia, independent regulations have been developed in New South Wales (NSW EPA, 2000), Queensland (Qld EPA, 2002), South Australia (S.A. EPA, 2006), Tasmania (Anonymous, 1999), Victoria (EPA Victoria, 2004), Western Australia (Anonymous, 2002) and nationally (NRMMC, 2004). All of these regulations are similar and specify regulation limits for a small number of OCPs (DDT/DDD/DDE, dieldrin, aldrin, lindane, chlordane, HCB, and heptachlor) and PCBs; both with maximum permissible concentration of 1 mg kg^-1 dw. There doesn’t appear to be a scientific basis for the Australian organic pollutant contaminant limits. In contrast to the low permissible contaminant levels the US EPA calculated predicted maximum contaminant limits that would results in unacceptable exposure to humans for aldrin/dieldrin (3.9 mg kg^-1 dw) chlordane (122.9 mg kg^-1 dw), Total DDT (171.4 mg kg^-1 dw), HCB (41.4 mg kg^-1 dw), lindane (120 mg kg^-1 dw) and PCBs (6.6 mg kg^-1 dw). They didn’t regulate these compounds because one of the following criteria was met: (1) the pollutant is banned for use, has restricted use or is not manufactured for use in the USA, (2) the pollutant is detected infrequently in sludge and is present is ≤ 5% of sludge samples or (3) the limit for an organic

pollutant derived from 503 exposure assessment is greater than the 99^th percentile

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concentration in sludge (U.S. EPA, 1994). There are regulations on the concentrations of OCPs and PCBs in Australian soils; dieldrin 10 mg kg^-1 dw, chlordane 50 mg kg^-1 dw, Total DDT 200 mg kg^-1 dw, heptachlor 10 mg kg^-1 dw and PCBs 10 mg kg^-1 dw. and these concentration limits are the most stringent of any classification type i.e. standard residential properties with accessible and/or garden that contributes < 10 % of the dietary vegetable and fruit intake (NEPC, 1999).

Interestingly, the concentrations recommended for the upper contaminant limits in residential soils is greater than that for sewage sludge for land application within Australia. There are no guidelines for the concentrations of these pesticides within agricultural soils.

The United States currently does not require biosolids to be monitored for organic pollutants (U.S. EPA, 1999), but in the past has required that biosolids contain no more than 10 mg kg^-1 dw of PCBs. The regulation of organic compounds was not done because at least one of the following criteria applied: the pollutant is banned for use, has restricted use or is not manufactured for use in the US; the pollutant is detected infrequently in sludge and is present in less than 5% of sludge samples; the limit for an organic pollutant derived from the 503 exposure assessment is greater than the 99^th percentile concentration in sludge (U.S. EPA, 1999). The European Union directive did not include pollutant limits for organic compounds. However, some countries have included organic compounds when determining their respective pollutant limits. The European Union has proposed revisions to its directive for organic compounds in biosolids. The proposed guidelines are given Table 1-4.

Table 1-4 European Commission proposed limits for concentrations of organic compounds in biosolids for use on agricultural land

Organic Compounds Proposed Limit Values mg kg^-1 dw Absorbable organically bound halogen

(AOX)

500

Linear alykyl sulphonate (LAS) 2,600

Di(2-ethylhexyl)phthaalte (DEHP) 100

Nonylphenol ethyoxylate (NPE) 50

Polyaromatic hydrocarbons (PAHs) 6

Polychlorinated biphenyls (PCBs) 0.8

Dioxin-like compounds 100 ng TEQ kg^-1 dw Reproduced from (European Commission, 2001)

These proposed changes may require a biosolids users to measure “Absorbable Halogen Compounds” (AOX) and this test will not only measure the loading of organochlorine pesticides but also other halogenated compounds such as PCBs, dioxin-like compounds, and brominated flame retardants (European Commission, 2001). Not only will AOX measurements also measure naturally occurring halogenated compounds (Asplund & Grimvall, 1991) but studies have shown that there is no relationship between chlorinated pollutants and AOX concentrations (Frost et al., 1993), which suggests that this test is too general to provide accurate

information about contaminant levels in biosolids and appropriate regulatory responses.