**3. Fertilizers** *versus* **contaminants**

There are three different categories of agricultural fertilizer: macronutrient fertilizer to supply major nutrients (N, P and K); macronutrient fertilizer to supply secondary nutrients [calcium (Ca), magnesium (Mg) and sulfur (S)] and micronutrients [Cu, Zn, Ni, Mn, iron (Fe), molyb‐ denum (Mo), boron (B), chlorine (Cl), sodium (Na), cobalt (Co) and silicon (Si)]. All of these nutrients can be applied through simple fertilizer (only one nutrient) or compound form (formulations with more than one nutrient).There is a further classification based on the essentiality of nutrients, where metals may be classified as essentials, such as B, Cu, Fe, Mn, Mo and Zn; beneficial, such as Co, Ni and V; and toxic, such as Cd, Cr, Hg and Pb. Thus, it should be noted that the essential and beneficial elements can become toxic at high concen‐ trations [30].

According to reports developed by the United States Environmental Protection Agency (USEPA) [31] and The Weinberg Group (requested by The Fertilizer Institute) [32], the main metal contaminants that are found in agricultural fertilizers are Cd, Cr, Co, Cu, Pb, Mo, Ni, Zn, arsenic (As), mercury (Hg) selenium (Se), vanadium (V) and radio 266 (Ra). It can be observed in this list, that among the metals commonly found as contaminants in fertilizers, occur the presence of micronutrients, required for plant development.

Currently in Brazil, the legislation that deals about soil contamination is Resolution n°. 420 of 2009 of the National Council of Environment (CONAMA) [28], which aims to establish the criteria and values that guide of soil quality as the presence of chemical substances, among them the toxic metals. The resolution establishes three categories of guiding values which are: The Reference Value Quality (RVQ) which is the concentration of a substance that will define the natural quality of the soil, based on previous studies for each Brazilian state, the Prevention Value (PV), which refers to the concentration limit of a substance in the soil, and the Investi‐ gation Value (IV) which is the concentration of a substance in the soil of which there are potential risks, direct or indirect, to human health. Table 2 shows the values set for preventing

However, the Resolution n°. 420 is being severely questioned by authorities and researchers, since it present several misconceptions that violate the Federal Constitution regarding the "preservation, enhancement and restoration of environmental quality propitious to life" (this

As (mg kg-1) 15.0 35.0 55.0 150.0 Cd (mg kg-1) 1.3 3.0 8.0 20.0 Pb (mg kg-1) 72.0 180.0 300.0 900.0 Cr (mg kg-1) 75.0 150.0 300.0 400.0 Hg (mg kg-1) 0.5 12.0 36.0 70.0

**Table 2.** Values guiding to the presence of toxic metals in Brazilian soils in accordance with Resolution n° 420 of 2009

There are three different categories of agricultural fertilizer: macronutrient fertilizer to supply major nutrients (N, P and K); macronutrient fertilizer to supply secondary nutrients [calcium (Ca), magnesium (Mg) and sulfur (S)] and micronutrients [Cu, Zn, Ni, Mn, iron (Fe), molyb‐ denum (Mo), boron (B), chlorine (Cl), sodium (Na), cobalt (Co) and silicon (Si)]. All of these nutrients can be applied through simple fertilizer (only one nutrient) or compound form (formulations with more than one nutrient).There is a further classification based on the essentiality of nutrients, where metals may be classified as essentials, such as B, Cu, Fe, Mn, Mo and Zn; beneficial, such as Co, Ni and V; and toxic, such as Cd, Cr, Hg and Pb. Thus, it should be noted that the essential and beneficial elements can become toxic at high concen‐

**IV Agricultural Area Residential Industrial**

issue will be addressed with greater emphasis on section 5 of this chapter).

and detecting toxic metals in soil.

110 Environmental Risk Assessment of Soil Contamination

**Metal PV**

PV: Prevention Value; IV: Investigation value

**3. Fertilizers** *versus* **contaminants**

of CONAMA [28]

trations [30].

According to USEPA [31], among the fertilizers used to supply macronutrients, the phosphate shown the highest levels of toxic metals (especially Cd), followed by nitrogen and potassium fertilizers. With respect to micronutrients, the sources used to obtain it are varied, resulting in the occurrence of fertilizers from low to high levels of metals. In general, micronutrient sources have higher level of contaminant in comparison to sources of macronutrients, on the other hand, are applied larger amounts of fertilizer to supply the macronutrients, therefore, the possibility of soil and environment pollution with the use of any type of contaminated fertilizer is real and should be seriously studied.

The presence of contaminants in fertilizers occurs most of the time with the use of industrial waste or low cost sources for raw materials. These sources, when treated and used properly and rationally, present themselves as a good alternative to agriculture, however its improper use can cause serious damage to the soil, plants and the human beings.

This fact becomes even more important in the case of fertilizers to supply micronutrients, which often are obtained from raw materials originated from industrial wastes, which may show, in addition of the desirable elements, toxic metals. In this situation, the benefits are highly attractive for the fertilizer industries, once these companies acquire low quality raw material at low costs, without generating any type of waste, incorporating everything in their products.

One of the main cases regarding the presence of contaminants in fertilizers happened in the 90s in the United States, where many farmers and social actors reported the possibility of the presence of toxic metals in these inputs. The impact generated and population pressure led to the development of several research regarding the contamination of fertilizers and soil pollution, culminating with the publication by the U.S. government, of the first law regulating the content of toxic elements in the United States in 1998. From these studies and based on Canadian law, in 2002, the USEPA published the federal law that regulates the production of fertilizers to supply Zn from industrial waste [33].

Another case reported in the literature is the presence of contaminants in raw materials from China. In a publication from the Washington Department of Ecology (WDE) [34] it was reported the presence of Cd in raw materials for the manufacture of fertilizers, with samples showing more than 20% of Cd, i.e., more than 200,000 ppm. It is also reported that the final products produced with the use of these contaminated sources presented 10,600 ppm of Cd. The report also warns that Cd present in the analyzed material does not naturally occur in natural mineral sources, leading to the conclusion that the incorporation of Cd or the use of wastes contaminated with this metal was occurred.

In Brazil, there are frequent reports of companies selling fertilizer, mineral and organic, outside the standard quality. The most common cases are related to the presence of nutrients amounts below the specified labels, since this factor is more investigated. However, there are few studies evaluating the presence of toxic metals in these inputs, although the few that were conducted demonstrated the presence of these contaminants in fertilizers [6, 35, 36].

Currently, most grain-producing countries and other plant materials have laws regarding the limits of metals in fertilizer, which are presented in Table 3, where it can be observed a large variation between the allowed values. In general, the stipulated limits are for metals in phosphate fertilizer and micronutrient fertilizers, but there are some normatives that consider fertilizers in general, regardless of its composition or purpose. The limits of toxic metals can also be determined based on the amounts of nutrients or total amount in fertilizers.


1 [38], 2 [39], 3 [40], 4 [41]; \* - Maximum allowed value per percentage point of P2O5 in the fertilizer; \*\* - Maximum allowed value per percentage point of the micronutrients sum in the fertilizer ; NA – not available

**Table 3.** International maximum limits of contaminants allowable in fertilizers


The Brazilian fertilizers law is based on the Normative Instruction (NI) 27/06 [37], which states like contaminating toxic metals, the elements As, Cd, Pb, Cr and Hg, determining the maxi‐ mum allowable limits of these metals in four different categories of fertilizers (Table 4).

In Brazil, there are frequent reports of companies selling fertilizer, mineral and organic, outside the standard quality. The most common cases are related to the presence of nutrients amounts below the specified labels, since this factor is more investigated. However, there are few studies evaluating the presence of toxic metals in these inputs, although the few that were conducted

Currently, most grain-producing countries and other plant materials have laws regarding the limits of metals in fertilizer, which are presented in Table 3, where it can be observed a large variation between the allowed values. In general, the stipulated limits are for metals in phosphate fertilizer and micronutrient fertilizers, but there are some normatives that consider fertilizers in general, regardless of its composition or purpose. The limits of toxic metals can

> **As Cd Pb Cr ------------------------- mg kg-1 ------------------------------**

also be determined based on the amounts of nutrients or total amount in fertilizers.

Switzerland1 Phosphate NA 50.0 NA NA Finland1 Phosphate NA 50.0 NA NA Sweden1 Phosphate NA 100.0 NA NA Norway1 Phosphate NA 100.0 NA NA Denmark1 Phosphate NA 110.0 NA NA Belgium1 Phosphate NA 210.0 NA NA Germany1 Phosphate NA 210.0 NA NA Austria1 Phosphate NA 275.0 NA NA U.S. (California)2 Phosphate 2.0\* 4.0\* 20.0\* NA U.S. (Washington)3 Phosphate 13.0 165.0 61.0 1.0 Australia1 Phosphate NA 300.0 NA NA Japan1 Phosphate 50.0 343.0 100.0 5.0 New Zealand1 Phosphate NA 280.0 NA NA U.S. (Texas)4 Anyone 41.0 39.0 300.0 17.0 Canada1 Anyone 75.0 20.0 500.0 NA China4 Anyone 50.0 8.0 100.0 NA U.S. (California) Micronutrient 13.0\*\* 12.0\*\* 140.0\*\* NA U.S. (Washington) Micronutrient 112.0\*\* 83.0\*\* 463.0\*\* 6.0\*\* Australia Micronutrient NA 50.0 2000.0 5.0

1 [38], 2 [39], 3 [40], 4 [41]; \* - Maximum allowed value per percentage point of P2O5 in the fertilizer; \*\* - Maximum

allowed value per percentage point of the micronutrients sum in the fertilizer ; NA – not available

**Table 3.** International maximum limits of contaminants allowable in fertilizers

demonstrated the presence of these contaminants in fertilizers [6, 35, 36].

**Country Fertilizer type**

112 Environmental Risk Assessment of Soil Contamination

\* - Maximum allowed value per percentage point of P2O5 in the fertilizer; \*\* - Maximum allowed value per percentage point of the micronutrients sum in the fertilizer; NA – Not Available.

**Table 4.** Maximum allowable limits for metal contaminants in Brazilian fertilizers [37]

There are some doubts in relation to NI 27/06, which consider the legislation incipient, since that it does not determines which raw materials can be used as sources of nutrients in the fertilizers. Nutrient sources for macronutrients generally present good quality, however, for micronutrients, the use of low quality materials is frequently observed in Brazil, as mentioned previously, resulting in a possible contamination of the environment.

The legislation also does not tell how it will be the inspection of fertilizers industries, moreover tolerating the presence of contaminants in amounts up to 30% higher than the accepted values (Table 4). Another worth mentioning fact, is that the limits should be revised, since Article 5 affirms the need of a revision of the values predicted by NI 27/06 four years after its publication.

Nowadays, still does not exist an adequate legislation in Brazil regarding the use of toxic waste in the production of micronutrients. However, there are technical studies which classify these elements as hazardous materials, an example is the NBR 10004 of the Brazilian Association of Technical Standards (ABNT) [42], which stablish that the use of this wastes may present a risk to public health, causing or contributing to an higher incidence of diseases and mortality, also presenting adverse effects on the environment when handled or disposed inappropriately.

Another issue that is being discussed by the scientific community is that the determination of contaminants limits in fertilizers provides for the industries the possibility to include, as a source of nutrients, contaminated materials or with low quality, i.e., by the laws, the govern‐ ment provided the industries, exactly what they wanted, the possibility to incorporate lowquality raw materials and contaminated to supply nutrients [43]. It is observed so that there is a strong influence of the fertilizer industry in the studies and laws that limit the contaminants in these materials, showing that this problem is not only related to the environmental field, but also with the political and economic sector.
