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STATE OF CALIFORNIA <br /> DEPARTMENT OF HEALTH SERVICES <br /> TOXIC SUBSTANCES CONTROL PROGRAM <br /> TOXICOLOGY AND RISK ASSESSMENT UNIT <br /> SCIENTIFIC GUIDANCE MEMO 89-3 <br /> AUGUST 9, 1989 <br /> Page 1 of 8 <br /> PENTACHLOROPHENOL <br /> A <br /> EALTH BASEDEXPOSUREGCRZTERIVATION OF <br /> A <br /> Pentachlorophenol <br /> (PCP) <br /> (CAS No. 87-86-5) is a pest4 :ide used <br /> extensively in California for wood preservation at lui„mer mills <br /> and wood processing facilities. PCP contamination of groundwater <br /> has been reported in seven California counties. <br /> Polychlorinated-p- <br /> dibenzo- dioxins (PCDDs) and polychlorinated <br /> dibenzofurans in PCP <br /> (PCDFs) have been found as intaminants pCP ontaminated <br /> preparations sold and used commercially, in round water. <br /> soils, and (at two wood treatment facilities) g using <br /> pCp has previously been regulated as a non-carcinogen, <br /> the relevant toxic end-point. Recent <br /> developmental toxicity as <br /> evidence indicates PCP poses a carcinogenic risk to humans. <br /> osure to PCP in <br /> Two recent studies of the efossfects <br /> of lifetime carcinogenic activity (National <br /> mice revealed that PCPP <br /> 1988) . Two grades of commercially available <br /> Toxicology Program, 1 <br /> or <br /> pCp (EC-7 and technical grade) were administered h the diet es <br /> the entire life span) to B6C3F1 mice. These two grades <br /> 2 years ( available PCP which are <br /> of PCP are representative them conditions of these studies, the <br /> still in use today• Undermined that there was clear <br /> Program National Toxicology g <br /> Of <br /> (NTP) determ (EC-7 grade) as shown by <br /> evidence of carcinogenic activity <br /> PCP <br /> dose-related increased incidencesles and liver femalesaandahemangiosarcomas <br /> (adrenaadrenal medullary <br /> l gland) tumors i <br /> (tumors of blood vessels) in females. The NTP also conclude <br /> Of <br /> that there was clear <br /> evidence <br /> d nCe*zcreasedrincidences ofcinogenic tliver and <br /> technical grade PCP as showny <br /> adrenal medullary tumors in PCP-treated male mice. Under the <br /> conditions of this study, -he NTP concluded that there was some <br /> evidence of carcinogenic activity of technical grade PCP in <br /> female mice as shown by an increase in <br /> the incidence of liver <br /> neoplasms and hemangiosarcomas. <br /> Toxicologists within the Toxicology and Risk Assessment Group of <br /> the Technical Services Tnit evaluated the data from the NTP <br /> f the <br /> n by <br /> nce 0 <br /> animal studies and found _e Ceaawasc was <br /> ent conclusions <br /> w <br /> concl dethat <br /> the NTP) that this evic <br /> pentachlorophenol poses a potential carcinogenic risk to humans. <br /> Therefore, the Toxicology and Risk Assessment Group has developed <br /> health-based exposure criteria (Applied Action Levels, AALs) for <br /> PCP based upon its carcinogenic activity. <br /> Commercial PCP typically contains impurities which include <br /> trichlorophenol , tetrachlorophenol , PCDDs and PCDFs. Since both <br /> dioxin (TCDD) and a mixture of <br /> 2 , 3 ,7 , 8-tetrachlorodiber,zo-p- vxCDD) isomers exhibit <br /> 2 3 ,7 , 8-hexachlorodibenz-_-p-dioxin (�� it was <br /> in animal studies, <br /> sufficient evidence of carcinogenicity . 11e w"ethe� <br /> necessary to analyze the NTP test articles to deter- <br />