**2.2.3 Statistical analysis**

142 Biomarker

as information related to working practices (such as years of employment and the use of

54 (64%) 31 (36%)

32.42±8.1

20-53


60 (70,6%) 25(29, 4%)

19 (22,4%) 66 (77,6%)

Exposure assessment was based on two techniques of air monitoring conducted simultaneously. First, environmental samples were obtained by air sampling with low flow pumps for 6 to 8 hours, during a typical working day. FA levels were measured by Gas Chromatography analysis and time-weighted average (TWA8h) was estimated according to the National Institute of Occupational Safety and Health method NIOSH 2541 (NIOSH, 1994).

The second method was aimed at measuring ceiling values of FA using Photo Ionization Detection (PID) equipment (11.7 eV lamps) with simultaneous video recording. Instantaneous values for FA concentration were obtained on a per second basis. This method allows establishing a relation between workers activities and FA concentration values, as well to

Measurements and sampling were performed in a macroscopic room, provided with fume

Evaluation of genotoxic effects was performed by applying the CBMN assay in peripheral

reveal the main exposure sources (McGlothlin et al., 2005; Viegas et al., 2010).

blood lymphocytes and exfoliated cells from the buccal mucosa.

**Control group Exposed group** 

37 (66%) 19 (34%)

39.45±11.5

20-61

14.5 1-33

45 (80,4%) 11 (19,6%)

19 (33,9%) 37 (66,1%)

protective measures). In this study, none of the participants were excluded.

**Number of subjects** 85 56

**Gender**  Females Masculine

**Age** 

**in years)**  Range

**in years)**  Range

Non-smokers Smokers

Non-drinkers Drinkers

**(mean ±standard deviation,** 

**Years of employment (mean ± sandard deviation,** 

**Tobacco consumption** 

**Alcohol consumption** 

Table 1. Characteristics of the studied sample.

hoods, always near workers breath.

**2.2.2 Biological monitoring** 

**2.2.1 Environmental monitoring of FA exposure** 

The deviation of variables from the normal distribution was evaluated by the Shapiro-Wilk goodness-of-fit test. The association between each of the genotoxicity biomarkers and occupational exposure to FA was evaluated by binary logistic regression. The biomarkers were dichotomized (absent/present) and considered the dependent variable in regression models where exposure was an independent variable. Odds ratios were computed to evaluate the risk of biomarkers presence and their significance was assessed. The nonparametric Kuskal-Wallis and Mann-Whitney U-tests, were also used to evaluate interactions involving confounding factors. All statistical analysis was performed using the SPSS package for windows, version 15.0.

#### **2.2.4 Results**

#### **FA exposure levels**

Results of FA exposure values were determined using the two methods described – the NIOSH 2541 method for average concentrations (TWA8h) and the PID method for ceiling concentrations. For the first exposure metric, FA mean level of the 56 individuals studied was 0.16 ppm (0.04 – 0.51 ppm), a value that lies below the OSHA reference value of 0.75 ppm. The mean ceiling concentration found in the laboratories was 1.14 ppm (0.18 – 2.93 ppm), a value well above the reference of the American Conference of Governmental Industrial Hygienists (ACGIH) for ceiling concentrations (0.3 ppm). As for the different tasks developed in histopathology laboratories, the highest FA concentration was identified during macroscopic specimens' exam. This task involves a careful observation and grossing of the specimen preserved in FA, therefore has direct and prolonged contact with its vapors (Table 2).

Genotoxicity Biomarkers: Application in Histopathology Laboratories 145

Regarding the impact of the duration of exposure to FA, the mean values of MN in lymphocytes and in buccal cells tended to increase with years of exposure (Table 5) but the

> **Mean NPB± S.E. (range)**

5.13±1.381 (0-10)

2.42±0.668 (0-9)

3.33±1.443 (0-14)

2.33±1.036 (0-15)

> **Mean NPB ± S.E. (range)**

> > 3.03±0.699 (0-15)

> > 2.95±0.818 (0-14)

> > 0.22±0.078 (0-3)

> > 0.10±0.071

**Mean NBUD± S.E. (range)**

1.38±0.498 (0-3)

1.53±0.731 (0-13)

0.33±0.188 (0-2)

0.73±0.248 (0-2)

> **Mean NBUD ± S.E. (range)**

1.34±0.418 (0-13)

0.42±0.158 (0-2)

0.11±0.043 (0-1)

(0-2) 0.00 0.26±0.122

**Mean MN buccal cells ± S.E. (range)** 

> 0.63±0.625 (0-5)

> 0.63±0.326 (0-6)

> 0.83±0.458 (0-5)

> > 1.20±0.8 (0-9)

> > > **Mean MN buccal cells± S.E. (range)**

1.14±0.353 (0-8)

0.74±0.495 (0-9)

0.11±0.057 (0-2)

(0-2)

association was not statistically significant.

**N** 

**> 5** 8 2.75±0.940

**6-10** <sup>19</sup> 3.05±0.775

**11 - 20** <sup>12</sup> 5.50±1.317

**>21** <sup>15</sup> 5.00±1.151

**Females** 37 4.43±0.676

**Males** 19 3.47±0.883

**Females** 54 0.87±0.229

**Males** 31 0.71±0.255

groups (p= 0.065) did not reach statistical significance.

NBUD means in the two groups (mean ± mean standard error, range)

**Mean MN lymphocytes ± S.E. (range)**

(0-8)

(0-12)

(0-14)

(0-13)

differ between men and women within the exposed and the controls (p> 0.05).

**Mean MN lymphocytes ± S.E. (range)**

(0-14)

(0-13)

(0-7)

(0-6)

Table 6. Descriptive statistics by gender of MN in lymphocytes and buccal cells, NPB, and

In order to examine the effect of age, exposed and non-exposed individuals were stratified by age groups: 20-30, 31-40, and ≥ 41 years old (Table 7). There was no consistent trend regarding the variation of biomarkers with age, the only exception being the MN in lymphocytes in the exposed group (Kruskal-Wallis, p= 0.006), where the higher means where found in the older group. According to Mann-Whitney test, there is a statistical significant result between the elder and the older group (20–30 and > 41 years old, p= 0.02), however the comparison between 20-30 and 31–40 groups (p= 0.262) and 30–40 and > 41

Table 5. Descriptive statistics according to years of exposure to formaldehyde of MN in lymphocytes and buccal cells, NPB, and NBUD means in the two groups (mean ± mean

Age and gender are considered the most important demographic variables affecting the MN index. However, Table 6 shows that the mean of all the genotoxicity biomarkers did not

**exposure** 

**Group Years of** 

standard error, range)

**Groups Gender N** 

**Exposed** 

**Exposed** 

**Controls** 


Table 2. FA ceiling values (ppm) by tasks in the macroscopy room.
