Genotoxic Evaluation of Mexican Welders Occupationally Exposed to Welding Fumes Using the Micronucleus Test on Exfoliated Oral Mucosa Cells: Data Set

Variables "case". Binary. Case exposed to welding fumes (1) or control (0) "age". Continuous. Participant's age in years. "bmi": Continuous. Body mass index (kg/m^2) "drink". Binary. Any level of alcohol consumption (1 positive, otherwise 0) "smoke". Binary. Any level of tobacco use (1 positive, 0 otherwise) "amalgam". Binary. Presence or absence of dental crowns (1 presence, 0 absence) "exp.years". Continuous. Number of years of exposure to welding-fumes. (0 for controls) "micronuclei". Discrete. Number of micronucleated cells per 2000 cells "binucleated". Discrete. Number of binucleated cells per 2000 cells "lobulated". Discrete. Number of lobed-nuclei cells per 2000 cells "pyknotic". Discrete. Number of pyknotic cells per 2000 cells "condensed". Discrete. Number of condensed-chromatin cells per 2000 cells "karyorrhexis"Discrete. Number of karyorrhectic cells per 2000 cells "karyolysis". Discrete. Number of karyolytic cells per 2000 cells Data set of n = 39 (20 welders and 19 controls). We obtained exfoliated epithelial cells from the participants' buccal mucosa by smearing the inside lining of the subjects' cheeks with a moistened wooden tongue-depressor. The smears were directly transferred to slides, and dried at room temperature. Afterwards, they were fixed in an 80% ethanol solution during 48 hours, and stained with acridine orange. An experienced reader, blind to the group to which samples belonged, observed the slides under 100x optic amplification with a Carl Zeiss IVFL Axiostar Plus microscope equipped with 450-490 nm fluorescence filters. Using the HUMNxl scoring criteria, she identified and counted the number of MNi and NA occurrences per 2000 observed cells per slide. The very low presence of women in the workforce of the welding industry in Mexico made impossible for us to find female welders, therefore all of the participants were male. Data are overdispersed and most variables do not follow a normal distribution. Use the 'describe' function of the 'psych' R package for descriptive statistics. Clean the data: http://dx.doi.org/10.6084/m9.figshare.1305591 Descriptive statistics and exploratory analysis: http://dx.doi.org/10.6084/m9.figshare.1305592 Statistical analysis: http://dx.doi.org/10.6084/m9.figshare.1305593

### 变量说明
1. `case`：二分类变量，赋值为1代表暴露于焊接烟尘（welding fumes）的病例组，赋值为0代表对照组。
2. `age`：连续型变量，为受试者的年龄（单位：年）。
3. `bmi`：连续型变量，即身体质量指数（Body Mass Index，BMI），单位为kg/m²。
4. `drink`：二分类变量，代表是否存在任何水平的饮酒行为（1为阳性，否则为0）。
5. `smoke`：二分类变量，代表是否存在任何水平的烟草使用（1为阳性，0为阴性）。
6. `amalgam`：二分类变量，代表是否存在牙科牙冠（1为存在，0为不存在）。
7. `exp.years`：连续型变量，为焊接烟尘暴露年限（对照组受试者赋值为0）。
8. `micronuclei`：离散型变量，每2000个细胞中的微核细胞数。
9. `binucleated`：离散型变量，每2000个细胞中的双核细胞数。
10. `lobulated`：离散型变量，每2000个细胞中的分叶核细胞数。
11. `pyknotic`：离散型变量，每2000个细胞中的固缩核细胞数。
12. `condensed`：离散型变量，每2000个细胞中的染色质浓缩细胞数。
13. `karyorrhexis`：离散型变量，每2000个细胞中的核碎裂细胞数。
14. `karyolysis`：离散型变量，每2000个细胞中的核溶解细胞数。

本数据集共纳入39例受试者，其中20名为焊接工人，19名为对照个体。

研究人员使用湿润的木质压舌板擦拭受试者颊黏膜内壁，采集脱落上皮细胞。将涂片直接转移至载玻片，于室温下自然晾干，随后置于80%乙醇溶液中固定48小时，并用吖啶橙（acridine orange）染色。由一名对样本分组不知情的经验丰富的阅片者，使用搭载450~490nm荧光滤光片的Carl Zeiss IVFL Axiostar Plus型显微镜，以100倍光学放大倍数观察玻片。依据HUMNxl评分标准，该阅片者对每张玻片每2000个观测细胞中的微核（MNi）与核异常（NA）发生数进行识别与计数。

由于墨西哥焊接行业劳动力中女性占比极低，研究团队无法招募女性焊接工人，因此本数据集所有受试者均为男性。

本数据集存在过度离散现象，且多数变量不服从正态分布。描述性统计分析可通过R语言`psych`包中的`describe`函数实现。
数据集清理代码：http://dx.doi.org/10.6084/m9.figshare.1305591
描述性统计与探索性分析代码：http://dx.doi.org/10.6084/m9.figshare.1305592
统计学分析代码：http://dx.doi.org/10.6084/m9.figshare.1305593