3. Results and discussion

#### 3.1 Metal concentration

approximately 80% moisture content of the fish fillet [45–47]; Cm is the metal concentration in the fish tissue, represented by the mean value of each trace metal at each population analyzed (here an upper confidence limit, UCL95 as show in Table 4, was considered as a conservative parameter of population central tendency); WAB is the average body weight for adults (for conservative purpose we assumed the average Brazilian adult body weight for woman, 59.6 Kg [48]); and TA is the average exposure time for non-carcinogens (EF � ED, [46]).

(n = 8) and DORM-3 (n = 8). u = standard deviation/√n; UCRM (Uncertainty, certified reference material) = kuc, where uc is the combined standard uncertainty and k is the coverage factor.

Element Obtained mean � u Certified value � UCRM Recovery (%)

Cd 22.7 � 0.4 24.3 � 0.8 94 Cu 30.3 � 0.5 31.2 � 1.1 97 Fe 1721 � 38 1833 � 75 94 Pb 0.131 � 0.001 0.16 � 0.04 84 Zn 106.5 � 2.7 116 � 6 92

Applied Geochemistry with Case Studies on Geological Formations, Exploration Techniques…

Cd 0.30 � 0.01 0.29 � 0.02 100 Cu 15.2 � 0.3 15.5 � 0.63 98 Fe 327.7 � 7.1 347 � 20 94 Ni 1.06 � 0.03 1.28 � 0.24 83 Zn 46.1 � 0.7 51.3 � 3.1 90

The risk of non-carcinogenic effects was investigated using the target hazard quotient (THQ), which is defined as the ratio between the EDI and the oral reference dose (RfD, mg/kg bw/day) following Eq. (2). This method for estimate THQ considers that for all the potential contaminants, the ingestion dose is equal to the absorbed dose, where cooking has no effect [49]. The RfD represents an estimate of the daily intake oral exposure of the human population that may be continually exposed over a lifetime without an appreciable risk of deleterious effects, and here the USEPA values were applied (0.001 Cd, 0.04 Cu, 0.7 Fe, 0.02 Ni, 0.004 Pb, and

As the area of study is contaminated with more than one of the potential contaminants evaluated here, and considering that exposure to two or more pollutants may cause additive effects [47], the cumulative health risk was evaluated by the sum of individuals THQ, expressed as in Eq. (3) as the total THQ (TTHQ).

TTHQ ¼ THQðtoxicant 1Þ þ THQðtoxicant 2Þ þ … THQðtoxicant nÞ (3)

In general, according to the literature [42, 46, 47, 50], values of THQ and TTHQ lower than 1 suggest that adverse hazard of the exposed population to the metals

One way ANOVA followed by parametric correlation (Pearson coefficient) was

used to compare metal contents among tissues, species, and the relationships

THQ ¼ EDI=RfD (2)

) in mass fraction of dry weight in certified reference material DOLT-4

0.3 Zn, [49]).

DOLT-4 (n = 8)

DORM-3 (n = 8)

Table 3.

Obtained and certified values (mg kg�<sup>1</sup>

evaluated is not expected.

2.5 Statistical analysis

116

Mean values, interval of confidence (at 95% level) and concentration ranges of Cd, Cu, Fe, Ni, Pb, and Zn contents, obtained for muscle and liver tissues, from the four fish species with different diet habits are shown in Table 4. The content of metals is expressed in dry weight, and wet weight (not shown) should consider approximately 80% moisture content of the fish fillet. Analysis of variance pointed that metal concentrations were significantly different (p < 0.05) between tissues for each analyzed species, with higher levels in liver than muscle tissue (except for Pb in Diapterus rhombeus and Ni in Centropomus parallelus). Iron and Zn were the most abundant elements in both tissues, being at least two orders of magnitude over Cu, Ni, Pb, and Cd contents, particularly in muscle tissue. In liver, Fe concentrations were 8–18 times higher than Zn and Cu, which were between one and four order of magnitude from Ni, Cd, and Pb concentrations.

Higher levels of metals (except Cd) were observed in both tissues (muscle and liver) of noncarnivorous over carnivorous species, alerting for an accumulation pattern related to diet habits. In muscle of Genidens genidens, for example, Fe and Zn were 4.3 and 8.7 times higher, respectively, in C. parallelus muscle and liver tissues.

Comparing to the global scenario (Table 5), Cd, Cu, Ni, and Pb contents in muscle and liver tissues of fish from the Santos-Cubatão Estuarine System were similar to levels found in other impacted environments with similar contaminated sources. However, levels for Fe and Zn stand out being even higher than those reported in the 1980s for Mugilidae, Ariidae, and Centropomidae species [16].

#### 3.2 Metal levels in fish and its relation with contaminated sediment

Two major pathways, or uptake vectors, are responsible for metal incorporation in detritus-feeding aquatic species: (1) ingestion of particles from metal-enriched sediments or (2) uptake by water from particles in suspension [57].

Here, higher levels of metals in tissues from noncarnivorous species suggested that in the impacted scenario of the Santos-Cubatão Estuarine System, the habits associated to the substrate were relevant. The literature suggests that studied area substrate shows a history of contamination related to a steel plant activity since the 1960s, with strong anomalies of Fe and Zn, which reach, in the first 20 cm of the overbank sedimentation, 17.6 4.6% of Fe and 541 146 mg kg<sup>1</sup> of Zn (Table 1) [12, 58]. These values are, respectively, ca. 5.5 and 8 times higher than those corresponding to the average composition of the shale [15] and are 5.9 (Zn) and 3.7 (Fe) times higher than the pre-industrial values in the study area [14]. As sediments are an item commonly found in omnivorous/detritivorous dietary habits, as Genidens genidens, Diapterus rhombeus, and Mugil liza [29, 31, 39, 59, 60], the data suggest that high Fe and Zn levels observed can be a consequence of the local sediment's intake.


Centropomus

significant

 differences

Family

119

Mugilidae

Santos Bay (Brazil) São Vicente Estuary (Brazil)

Turkey Karoun River (Iran)

Tuzla Lagoon Spring season

(Turkey)

Arridae

Paranaguá Estuary (Brazil)

Santos Bay (Brazil)

Gulf of Paria (Venezuela)

Centropomidae

 Vitoria Bay (Brazil)

Santos Bay (Brazil)

> Mojarra

Table 5.

Contents of Cd, Cu, Fe, Pb, Ni, and Zn (mg kg1, dry weight) in muscle and liver tissues of some specimens of Mugilidae,

subtropical

 world.

Gulf of Paria (Venezuela)

 Muscle

 Muscle

 Muscle

 Muscle

 Muscle

 Muscle

 4.71

 2.31

 0.65

 0.36

—

0.01

 Ariidae,

Centropomidae,

 and Gerreidae families around the tropical/

 0.02

—

 —

[55]

 0.06

—

0.67

 0.07

0.28

—

0.09

—

5.68

[16]

 6.8

 0.03

 0.01

 0.04

 0.04

 14.4

 0.4

 [56]

 0.9

 3.13

 1.76

 1.35

 0.38

—

0.08

 0.20

 0.12

 0.23

 0.06

—

1.06

 0.20

0.82

—

 —

0.09

0.15

 0.05

 40.42

 19.20

17.15

[16]

[55]

 [54]

Implications of Sediment Geochemistry and Diet Habits in Fish Metal Levels…

 Muscle

 Liver Muscle

Liver

Muscle

Liver

Muscle

Liver

 0.35

 0.17

 5.74

 3.11

 305.0

 179.60

 1.85

 0.11

—

28.3

 3.71

 0.08

 0.01

 0.62

 0.008

 11.12

 4.13

 1.19

 0.44

—

60.86

 56.10

 [6]

 0.52

 0.03

—

13.5

 0.11

 1.03

 0.13

—

 —

 0.84

 0.08

—

0.73

 0.06

 1.75

 0.10

—

 —

[53]

DOI: http://dx.doi.org/10.5772/intechopen.89872

 1.64

 0.91

 202.8

 265.8

 370.43

 252.7

 12.59

 5.8

—

110.03

 34.58

 0.66

 0.08

 4.41

 1.67

 38.71

 18.28

 5.32

 2.33

—

37.39

 6.88

 [52]

—

7.67

 1.22

 24.37

 55.25

—

4.59

 1.38

 103.49

 18.92

 [51]

 0.06

Region

Tissue

 Cd

Cu 0.61

—

0.10

—

6.74

[16]

Fe

Pb

Ni

Zn

 References

 in metal levels. UCL95 was calculated using the USEPA free software ProUCL.

 parallelus,

Genidens genidens,

Diapterus rhombeus,

 and Mugil liza. Variance values (F) between

concentrations

 in tissues for each element are in bold for p < 0.05 indicating

Applied Geochemistry with Case Studies on Geological Formations, Exploration Techniques…


Implications of Sediment Geochemistry and Diet Habits in Fish Metal Levels… DOI: http://dx.doi.org/10.5772/intechopen.89872

> TableContents

 of Cd, Cu, Fe, Pb, Ni, and Zn (mg kg1, dry weight) in muscle and liver tissues of some specimens of Mugilidae,

subtropical

 world.

 Ariidae,

Centropomidae,

 and Gerreidae families around the tropical/

C. parallelus

118

G. genidens

D. rhombeus

M. liza

n=7

(Detritivorous)

n=8

(Omnivorous)

n=8

(Omnivorous)

n = 21 (Carnivorous)

M

Cd

 Mean

0.0013

0.06

66.8

0.003

0.24

24.37

0.002

0.25

11.07

0.001

0.26

22.34

0.0016

0.39

0.001–0.02

0.06–0.43

0.38

0.05–0.70

0.004

0.001–0.006

0.33

0.06–0.44

0.003

0.001–0.004

0.07

0.03–0.14

0.0016

UCL95

Min-Max

Cu

 Mean

0.61

12.2

221.3

1.29

26.1

35.39

0.79

10.9

114.2

0.79

176

70.10

0.98

224

0.52–1.15

102–226

12.8

8.20–15.6

0.94

0.42–1.03

34.0

6.14–42.1

1.45

0.92–1.69

13.5

6.66–21.4

UCL95

0.63

0.51–0.73

Min-Max

Fe

 Mean

7.21

822

242.3

39.5

9041

24.07

9.71

2468

14.74

20.3

2085

17.87

25.4

3675

13.4–30.1

517–3755

3221

312–4257

11.3

6.96–14.9

12,517

2720–18,490

0.13

5.02

0.05

0.31

8.06

0.36

1.17

5.02

Applied Geochemistry with Case Studies on Geological Formations, Exploration Techniques…

0.53

1.79

0.03–0.50

0.50–1.79

0.49

0.05–0.81

0.07

0.04–0.50

0.19

0.05–0.24

44.0

30.9–49.8

912

402–1181

UCL95

8.30

0.60–14.6

Min-Max

Ni

 Mean

0.05

0.06

0.53

 0.07 0.096

0.04–0.010

0.07

0.01–0.11

0.06

UCL95

Min-Max

Pb

 Mean

0.009

0.019

17.3

0.07

7.80

10.62

0.80

0.34

1.09

 0.06

1.13

83.09

0.11

1.50

0.01–0.22

0.79–1.54

1.04

0.002–1.42

1.58

0.002–2.80

12.29

0.93–21.8

0.09

0.02–0.09

0.029

0.006–0.031

UCL95

0.013

0.002–0.03

Min-Max

Zn

 Mean

17.2

64.8

272.8

80.5

1201

126.4

25.2

138

33.64

11.8

188

7.85

13.4

392

60.0–444

9.3–14.8

175

82.3–229

32.1

11.7–39.2

 and maximum)

 in mass fraction of dry weight of muscle (M) and liver (L) samples of

concentrations

 in tissues for each element are in bold for p < 0.05 indicating

1387

934–1658

113

29.3–189

69.7

38.3–86.0

18.04

13.6–20.7

UCL95

Min-Max

Table 4.

Mean metal contents (mg kg1), the interval of confidence at 95% level, and the extreme values (minimum

Centropomus

significant

 differences

 in metal levels. UCL95 was calculated using the USEPA free software ProUCL.

 parallelus,

Genidens genidens,

Diapterus rhombeus,

 and Mugil liza. Variance values (F) between

0.05–0.13

0.001–0.004

 L

 F

 M

 L

 F

 M

 L

FM

LF

Cadmium, Cu, Ni, and Pb anomalies were lower than Fe and Zn in the study area surface sediments (Table 1), which can explain the lower Cd, Cu, Ni, and Pb contents observed in the fish tissues (Table 4). In fact, other studies have observed that Fe and Zn occur in much higher proportions in bioavailable fractions from the study area sediments than other metals (Fe >>> Zn >> Cu > Pb > Ni >> Cd) [11, 61].

carnivorous species (Table 2) vary according to their origin. In general, the predator catches its prey in both sedimentary substrate and water column, and these sources show distinct contamination levels [63] that are consequently transferred to

Implications of Sediment Geochemistry and Diet Habits in Fish Metal Levels…

Centropomus parallelus is considered exclusively carnivorous, with 90% of its stomach contents consisting of small animals (fish, crustaceans, polychaetes, and insects), especially other fish that account for 70% of the weight of the content found [39]. This species is classified as sight-feeder, and it tries to capture any moving particle in the water; once in the mouth, it is ingested or rejected,

depending on its taste and texture [64]. The variability of prey of possibly different sources is represented by large scores (between 2.7 and 3.6) for the carnivorous species liver samples in component 2 (Figure 2). Differences between metal contents in tissues can be observed in Figure 2, where two distinct groups represent muscle and liver samples. Component 1 showed, approximately, the same score range for all four species, although tissues from detritivorous and omnivorous species presented muscle and liver domains better separated than carnivorous species. This can be a result of a more varied eating habit of the carnivorous species, and this behavior is better explained by the second principal component (see

In general, component 1 showed more disperse liver samples than muscle samples, and it can be a consequence of diet, metabolism, and environmental conditions. Since metals reach the hepatic organ by bloodstream after absorption, the first principal component in respect to liver samples reflects the chemical contrast common in the studied estuarine environment, in which metal levels are heterogeneous spatially [14, 65]. In opposition to the homogeneity expressed by component 1, the metal contents in muscle samples shown in Figure 2 seem to represent storage of metals during a longer time after internal metabolism and redistribution among tissues. Following uptake into the bloodstream, contaminants are redistributed to high metabolic organs such as the liver, for transformation and detoxification, and then to low metabolic ones, including muscles [4, 66]. Mainly because of the large amount of metallothionein, metal levels in the liver rapidly increase during exposure [6, 7, 67, 68] and are proportional to the levels present in the environment. In contrast, the muscle is the final tissue for metal storage after transformation and

In relation to human consumption, muscle tissues (usually humans do not eat fish liver) require special attention because of toxicity risk. When metal contents exceed the maximum levels established for these contaminants in food, it should be considered unfit for human consumption [5]. In Brazil, the Health Department determined maximum values for fish in natura of 0.05 mg kg<sup>1</sup> for Cd (with exception for some species as Mojarra and mullet, for which the limit is

) and 0.3 mg kg<sup>1</sup> for Pb [70]. In a less specific legislation, maximum

) for general food [71, 72] are established. Recalculating the metal

For Cd, Cu, Ni, and Zn, the concentrations are below the limits to offer danger-

contents listed in Table 4 to wet weight values, most Pb levels in the Diapterus rhombeus specimens exceeded the Brazilian legislation limit. Lead contents in the other noncarnivorous species analyzed also deserve attention being extremely close

ous to human consumption, and just ingestion of large amounts of fish would

), Ni (5 mg kg<sup>1</sup>

), and Zn

the prey differently.

DOI: http://dx.doi.org/10.5772/intechopen.89872

below).

excretion of some contaminants [1, 69].

permissible concentrations for Cu (30 mg kg<sup>1</sup>

to the limits set forth by the law.

3.4 Health risk assessment

0.1 mg kg<sup>1</sup>

(50 mg kg<sup>1</sup>

121

In respect to metal uptake from water, the literature has shown that processes altering redox potential of sediments and chemical forms of metals can promote the flux of metals from sediments to water [62]. Because the diet of noncarnivorous fish consists mainly of benthic organisms (animals and vegetables), and the metal load in the water column of the sampling sites proved to be relatively low [11], the metal levels detected in tissues of these fish seem to reflect the pollution level of the sediment and its biota, rather than the prevailing pollution state of the water.

### 3.3 Metal in tissues and diet habits

Differences between metal contents in tissues and their correlations with diet habits were depicted by applying principal component analysis (PCA; Figure 2). Here only two principal components were considered, and they explained 75.85% (carnivorous species) and 82.91% (detritivorous and omnivorous species) of the total variance in the original data set.

The higher metal intake of noncarnivorous species, especially in respect to Zn and Fe as a consequence of their eating habits and consumed items, is shown in the second principal component in PCA (Figure 2). The food items of detritivorous and omnivorous species (Table 2) are associated with the contaminated substrate, and thus the small dispersion observed in component 2 (score between 0.5 and 1.0; Figure 2) indicates this single source for metals. In contrast, food items of

#### Figure 2.

Scatter plots of the scores on the first two principal components (explained 75.85% of carnivorous species and 82.91% of detritivorous and omnivorous species) of the total variance in the original data set, obtained using Cd, Cu, Fe, Ni, Pb, and Zn. The black symbols represent the carnivorous species (C. parallelus, n = 17), and white symbols represent the omnivorous and detritivorous species (G. genidens, D. rhombeus, and M. liza; n = 20). The squares represent the muscle tissue and the triangles represent the liver tissue.

Implications of Sediment Geochemistry and Diet Habits in Fish Metal Levels… DOI: http://dx.doi.org/10.5772/intechopen.89872

carnivorous species (Table 2) vary according to their origin. In general, the predator catches its prey in both sedimentary substrate and water column, and these sources show distinct contamination levels [63] that are consequently transferred to the prey differently.

Centropomus parallelus is considered exclusively carnivorous, with 90% of its stomach contents consisting of small animals (fish, crustaceans, polychaetes, and insects), especially other fish that account for 70% of the weight of the content found [39]. This species is classified as sight-feeder, and it tries to capture any moving particle in the water; once in the mouth, it is ingested or rejected, depending on its taste and texture [64]. The variability of prey of possibly different sources is represented by large scores (between 2.7 and 3.6) for the carnivorous species liver samples in component 2 (Figure 2). Differences between metal contents in tissues can be observed in Figure 2, where two distinct groups represent muscle and liver samples. Component 1 showed, approximately, the same score range for all four species, although tissues from detritivorous and omnivorous species presented muscle and liver domains better separated than carnivorous species. This can be a result of a more varied eating habit of the carnivorous species, and this behavior is better explained by the second principal component (see below).

In general, component 1 showed more disperse liver samples than muscle samples, and it can be a consequence of diet, metabolism, and environmental conditions. Since metals reach the hepatic organ by bloodstream after absorption, the first principal component in respect to liver samples reflects the chemical contrast common in the studied estuarine environment, in which metal levels are heterogeneous spatially [14, 65]. In opposition to the homogeneity expressed by component 1, the metal contents in muscle samples shown in Figure 2 seem to represent storage of metals during a longer time after internal metabolism and redistribution among tissues. Following uptake into the bloodstream, contaminants are redistributed to high metabolic organs such as the liver, for transformation and detoxification, and then to low metabolic ones, including muscles [4, 66]. Mainly because of the large amount of metallothionein, metal levels in the liver rapidly increase during exposure [6, 7, 67, 68] and are proportional to the levels present in the environment. In contrast, the muscle is the final tissue for metal storage after transformation and excretion of some contaminants [1, 69].

### 3.4 Health risk assessment

In relation to human consumption, muscle tissues (usually humans do not eat fish liver) require special attention because of toxicity risk. When metal contents exceed the maximum levels established for these contaminants in food, it should be considered unfit for human consumption [5]. In Brazil, the Health Department determined maximum values for fish in natura of 0.05 mg kg<sup>1</sup> for Cd (with exception for some species as Mojarra and mullet, for which the limit is 0.1 mg kg<sup>1</sup> ) and 0.3 mg kg<sup>1</sup> for Pb [70]. In a less specific legislation, maximum permissible concentrations for Cu (30 mg kg<sup>1</sup> ), Ni (5 mg kg<sup>1</sup> ), and Zn (50 mg kg<sup>1</sup> ) for general food [71, 72] are established. Recalculating the metal contents listed in Table 4 to wet weight values, most Pb levels in the Diapterus rhombeus specimens exceeded the Brazilian legislation limit. Lead contents in the other noncarnivorous species analyzed also deserve attention being extremely close to the limits set forth by the law.

For Cd, Cu, Ni, and Zn, the concentrations are below the limits to offer dangerous to human consumption, and just ingestion of large amounts of fish would

Cadmium, Cu, Ni, and Pb anomalies were lower than Fe and Zn in the study area surface sediments (Table 1), which can explain the lower Cd, Cu, Ni, and Pb contents observed in the fish tissues (Table 4). In fact, other studies have observed that Fe and Zn occur in much higher proportions in bioavailable fractions from the study area sediments than other metals (Fe >>> Zn >> Cu > Pb > Ni >> Cd)

Applied Geochemistry with Case Studies on Geological Formations, Exploration Techniques…

In respect to metal uptake from water, the literature has shown that processes altering redox potential of sediments and chemical forms of metals can promote the flux of metals from sediments to water [62]. Because the diet of noncarnivorous fish consists mainly of benthic organisms (animals and vegetables), and the metal load in the water column of the sampling sites proved to be relatively low [11], the metal levels detected in tissues of these fish seem to reflect the pollution level of the sediment and its biota, rather than the prevailing pollution state of the water.

Differences between metal contents in tissues and their correlations with diet habits were depicted by applying principal component analysis (PCA; Figure 2). Here only two principal components were considered, and they explained 75.85% (carnivorous species) and 82.91% (detritivorous and omnivorous species) of the

The higher metal intake of noncarnivorous species, especially in respect to Zn and Fe as a consequence of their eating habits and consumed items, is shown in the second principal component in PCA (Figure 2). The food items of detritivorous and omnivorous species (Table 2) are associated with the contaminated substrate, and thus the small dispersion observed in component 2 (score between 0.5 and 1.0; Figure 2) indicates this single source for metals. In contrast, food items of

Scatter plots of the scores on the first two principal components (explained 75.85% of carnivorous species and 82.91% of detritivorous and omnivorous species) of the total variance in the original data set, obtained using Cd, Cu, Fe, Ni, Pb, and Zn. The black symbols represent the carnivorous species (C. parallelus, n = 17), and white symbols represent the omnivorous and detritivorous species (G. genidens, D. rhombeus, and M. liza;

n = 20). The squares represent the muscle tissue and the triangles represent the liver tissue.

[11, 61].

Figure 2.

120

3.3 Metal in tissues and diet habits

total variance in the original data set.

predator to high levels of toxic elements, such as Cu and Pb (not essential and

exert higher influence on metal levels in fish tissues (muscle and liver) than

We thank the São Paulo State Research Funding Agency—FAPESP (process number 08-11511-8) and the Brazilian National Council for Scientific and Technological Development (process 432922/2016-4)—for financial support. Bosco-Santos thanks the Brazilian Council for Scientific and Technological Development—CNPq

This study showed that high Fe and Zn contents found in fish tissues reflect the anomalous concentrations in contaminated sediments. The highest metal contents were found in the liver of noncarnivorous species, protein not normally consumed by humans, but can put at risk predators that eat the whole fish (aquatic birds, fish, and marine mammals). The results showed that fish eating habits, associated with contamination levels in sediments, play an important role in metal uptake. They can

, respectively.

without metabolic function), which can exceed 50 and 5 mg kg<sup>1</sup>

Implications of Sediment Geochemistry and Diet Habits in Fish Metal Levels…

4. Conclusion

bioaccumulation by trophic level.

DOI: http://dx.doi.org/10.5772/intechopen.89872

—for granting her with a master fellowship.

Alice Bosco-Santos\* and Wanilson Luiz-Silva

provided the original work is properly cited.

\*Address all correspondence to: alicebosco@gmail.com

Institute of Geosciences, University of Campinas, Campinas, Brazil

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Acknowledgements

Author details

123


Table 6.

The RfD values and estimated EDI (mg/kg bw/day) and THQ (mg/kg bw/week) by the study area population through the consumption of captured fish from the Santos-Cubatão estuarine system.

present this kind of concern. For Zn, for example, just the consumption of 2.5 kg of Genidens genidens muscle tissue would approach the limit. From all the metals evaluated, Cd is of least concern, since the World Health Organization [73] has determined the provisional tolerable weekly Cd intake of 25 μg kg<sup>1</sup> body weight, which means an intake of over a thousand pounds of fish to exceed this limit.

The estimated daily intake (EDI) were higher for Zn and Fe, followed by Cu for all analyzed species (Table 6), presenting a maximum value of 0.038 mg/kg bw/day for G. genidens. The lowest EDI values were reported for Cd followed by Pb and Ni. Using those EDI values and taking in account the USEPA RfDs, the THQ for each metal in each fish population was calculated, and it is shown in Table 6. The highest value of THQ was observed for Pb at the D. rhombeus population (0.134), while the lowest was observed for Cd at the C. parallelus population (0.0005). None of the metals individually exceeded the hazard quotient threshold of 1, implying that the level of daily intake of each examined metal for Brazilian population was lower than that of respective dose. The same happened for TTHO (varying from 0.03 for C. parallelus to 0.18 for D. rhombeus) that evaluate the cumulative health risks, reinforcing no potential significant health risks. Those observations suggest that the levels of human exposure to the analyzed metals should not cause any deleterious (noncarcinogenic) effect from the intake of fish species from study area (Table 6).

#### 3.5 Marine conservation risk assessment

Metal levels in fish liver tissue should be a concern when it comes to marine conservation. In organisms that have aerial respiration (e.g., seabirds and marine mammals), the intake of contaminants is mainly made by food, and biomagnification is usually observed [74]. Although the levels that can cause bad effects to marine organisms vary with the species and metals, the average consumption of 1 kg of Mugil liza or Genidens genidens studied here, for instance, can expose the

Implications of Sediment Geochemistry and Diet Habits in Fish Metal Levels… DOI: http://dx.doi.org/10.5772/intechopen.89872

predator to high levels of toxic elements, such as Cu and Pb (not essential and without metabolic function), which can exceed 50 and 5 mg kg<sup>1</sup> , respectively.
