Effects of transplacental exposure to chlorinated phenols.

Female rats were exposed to 0, 5, 50 or 500 ppm of 2-chlorophenol (2-CP) or pentachlorophenol (PCP). The study was designed to produce progeny which were exposed to the chlorophenolic compounds both prenatally and postnatally. Percent conception, litter size, birth weight, and number of stillbirths was determined at parturition. Hematologic parameters and body weights of the progeny were recorded at weaning age (3 weeks). Effects on reproduction were observed in both the 2-CP and PCP-exposed groups, as indicated by decreased litter sizes and increased number of stillborn. The data indicate that these chlorinated phenolic compounds may be feto- or embryotoxic at high doses. Effects on hematologic parameters were not observed. Further study involving transplacental and chronic exposures to these chlorophenolic compounds appears warranted.

2-Chlorophenol is a commercially produced chemical used as an intermediate in the production of higher chlorinated phenols. The generation of waste sources from the commercial production of 2-chlorophenol, its chemically derived products, and the inadvertent formation of 2-chlorophenol due to chlorination of organics in drinking and waste waters are potential sources of environmental contamination (1).
Pentachlorophenol (PCP) and its salts have been widely used in agriculture and industry since 1936 (10). Approximately 200 million pounds of PCP were produced worldwide in 1977 (11). Principal uses of PCP are as a pesticide and wood preservative (12), and contamination of livestock occurs by licking treated wood or drinking from vats used to treat wood (6). Industrial exposure and consumption of contaminated food and water are the principal sources of exposure to humans (13).
This study was conducted to assess the effects of two chlorophenolic compounds, 2-chlorophenol and pentachlorophenol, on reproduction and hematology. The experimental design included prenatal and postnatal exposure to the chlorophenolic compounds.

Materials and Methods
Female Sprague-Dawley rats were weaned at 21 days of age and divided into groups of 12-20 rats each. The rats were placed on dietary regimens containing 0, 5, 50 or 500 ppm 2-CP (Aldrich Chemicals, 97% pure) in the drinking water or PCP (ICN Pharmaceuticals, K & K Laboratories No. 18497, 95% pure) in the feed. The female rats were housed four per cage in stainless hanging wire racks. Feed and water were available ad libitum. The rats were bred at 90 days of age (10 weeks exposure). The dams were transferred to polyearbonate cages with stainless steel lids and hardwood shavings to litter. The study was designed to produce progeny that were exposed to the chlorophenolic contaminants both prenatally and postna-tally. Percent conception, litter size, birth weight, and number of stillbirths was determined at parturition. Body weights and hematologic parameters (white and red cell counts, hemoglobin, packed cell volume and mean corpuscular volume) were recorded at weaning age. Blood samples were analyzed using a Coulter counter, Model ZBi. The dams were terminated at weaning and liver and kidney tissues were collected for analysis of chlorophenolic content. Gas chromatography was used to analyze 2-CP and PCP in tissues by the methods of Erney (14).

Results
Parameters relating to reproductive performance that were observed include percent conception of EXON AND KOLLER the dams, litter size, birth and weaning weights, percent stillborn, survival to weaning and body weight gain of the dams (Tables 1-4). Percent conception was greater in all treatment groups as compared to controls (Tables 1 and 2). Litter size was significantly (p -0.05) decreased in groups of dams treated with high levels of 2-CP (Table 1). Litter size was also decreased in groups given 500 ppm PCP (p -0.10) ( Table 2). Percent of stillborn pups born to dams receiving either 2-CP or PCP was generally greater as compared to controls. This increase was significant (p -0.05) in the 500 ppm 2-CP group (Table 1). Body weights at weaning were generally decreased in PCP-exposed groups. No consistant effects were observed in regard to survival to weaning (Tables 3 and 4). The body weight gains of dams prior to breeding appeared to be unaffected by the treatments.  bExclusive of stillborn pups. bExclusive of stillborn pups. bA pool of tissues from five rats/group. The accumulation of the chlorophenol compounds in tissues of dams was comparatively minimal (Table 5). Pentachlorophenol levels in liver and kidney tissues were considerably lower than 2-CP residues in similar tissues. Residues in kidney versus liver tissue were approximately equal. Feed samples were also analyzed for PCP content ( Table  5). The analysis correlated reasonably well with the target concentrations of 5, 50 and 500 ppm. Purity of the PCP mixture used in preparation of the PCP diet was analyzed by the Dow Chemical Company ( Table 6). This analysis incidated that the PCP formulation was only 85.5% pure as compared to the 95% purity advertised by the manufacturer. The dioxin content was also determined ( Table 6).
Hematologic parameters examined for all treatment groups included red and white blood cell counts, packed cell volume (hematocrit), hemoglobin and mean corpuscular volume (Tables 7 and 8). No significant effects of chlorinated phenols on hematologic parameters were observed.

Discussion
The chlorophenols tested, 2-CP and PCP, appeared to alter certain reproduction parameters in rats. Stimulated conception rates, reduced litter size at the highest doses (500 ppm), and increased number of stillbirths were observed in chlorophenol-treated groups. These results indicate that high levels of these compounds tend to be fetoor embryotoxic. a2-Chlorophenol was given in the drinking water either prenatally by exposing the dams from weaning through parturition (90 days) and postnatally from parturition.
bAll hematologic parameters are reported as mean (standard deviation). 2) aPentachlorophenol was given in the drinking water either prenatally by exposing the dams from weaning through parturition (90 days) and postnatally from parturition.
'All hematologic parameters are reported as mean (standard deviation).
The results are consistent with those published by others (15). The majority of commercially prepared technicalgrade PCP is a mixture of about 85-90% PCP and the remainder primarily consists oftetrachlorophenol and chlorinated phenoxyphenols (16). Small amounts of other impurities include chlorinated dibenzo-pdioxins, chlorinated dibenzofurans and chlorinated diphenyl ethers. The mixture purchased for this study was listed by the manufacturer to be 95% pure PCP. However, analysis indicated that the mixture contained actually 85.5% PCP and a variety of other phenolics and impurities. Nevertheless, exposure to this substance in the environment would be as prepared containing both the PCP and associated impurities. Once adverse effects are identified from exposure to the manufactured product, then analytical grade PCP must be evaluated to determine if the effects are produced by PCP, its impurities or from a combination of these products.