Analisis pajanan benzena melalui biomarker s-phenylmercapturic acid (S-PMA) urin dan jumlah leukosit pekerja industri alas kaki informal di Desa Sukajaya Kecamatan Tamansari Kabupaten Bogor Jawa Barat = Benzene exposure analysis by biomarker s-phenylmercapturic acid s-pma urine concentration and leukocyte count of informal footwear workers in Sukajaya Village Kecamatan Tamansari Bogor Regency West Java