2.4 Human health risk assessment

The estimated daily intake (EDI) for Cd, Cu, Fe, Ni, Pb, and Zn (on muscle tissue) was calculated following Eq. (1) (after Saha & Zaman, [42]):

$$\text{EDI} = \left[ (\text{E}\_F \times \text{E}\_D \times \text{F}\_{IR} \times \text{C}\_F \times \text{C}\_m) / (W\_{AB} \times T\_A) \right] \times \text{10}^{-3} \tag{1}$$

When considering the conservative approach, EF is the exposure frequency (365 days/year); ED is the exposure duration (we considered a lifetime of 78 years, average of Brazilians [43]); FIR is the ingestion rate (g/person/day, where we considered 71 g/day, as recorded by the Food and Agricultural Organization [44]); CF is the conversion factor (0.208) to convert fresh weight to dry weight considering

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


between the trace metal levels in the tissues and the specimens' length and weight. A p < 0.05 was considered statistically significant, and all statistical tests were carried out using the OriginPro (v.8.6) graphing and data analysis software. Additionally, principal component analysis (PCA) was used to classify and

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

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

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

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].

Two major pathways, or uptake vectors, are responsible for metal incorporation in detritus-feeding aquatic species: (1) ingestion of particles from metal-enriched

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

3.2 Metal levels in fish and its relation with contaminated sediment

sediments or (2) uptake by water from particles in suspension [57].

differentiate samples between different tissues.

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

order of magnitude from Ni, Cd, and Pb concentrations.

3. Results and discussion

3.1 Metal concentration

tissues.

sediment's intake.

117

#### Table 3.

Obtained and certified values (mg kg�<sup>1</sup> ) in mass fraction of dry weight in certified reference material DOLT-4 (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.

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]).

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 0.3 Zn, [49]).

$$\text{THQ} = \text{EDI/RfD} \tag{2}$$

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).

$$\text{TTHQ} = \text{THQ}(\text{txicant 1}) + \text{THQ}(\text{txicant 2}) + \dots \text{THQ}(\text{txicant n}) \quad \text{(3)}$$

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 evaluated is not expected.

#### 2.5 Statistical analysis

One way ANOVA followed by parametric correlation (Pearson coefficient) was used to compare metal contents among tissues, species, and the relationships

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

between the trace metal levels in the tissues and the specimens' length and weight. A p < 0.05 was considered statistically significant, and all statistical tests were carried out using the OriginPro (v.8.6) graphing and data analysis software. Additionally, principal component analysis (PCA) was used to classify and differentiate samples between different tissues.
