Subchronic administration of technical pentachlorophenol to lactating dairy cattle: performance, general health, and pathologic changes

Pentachlorophenol-Induced Cytotoxic, Mitogenic, and Endocrine-Disrupting Activities in Channel Catfish, Ictalurus punctatus

Pentachlorophenol (PCP) is an organochlorine compound that has been widely used as a biocide in several industrial, agricultural, and domestic applications. Although it has been shown to induce systemic toxicity and carcinogenesis in several experimental studies, the literature is scarce regarding its toxic mechanisms of action at the cellular and molecular levels. Recent investigations in our laboratory have shown that PCP induces cytotoxicity and transcriptionally activates stress genes in human liver carcinoma (HepG2) cells [1]. In this research, we hypothesize that environmental exposure to PCP may trigger cytotoxic, mitogenic, and endocrine-disrupting activities in aquatic organisms including fish. To test this hypothesis, we carried out in vitro cultures of male channel catfish hepatocytes, and performed the fluorescein diacetate assay (FDA) to assess for cell viability, and the Western Blot analysis to assess for vitellogenin expression following exposure to PCP. Data obtained from FDA experiments indicated a strong dose-response relationship with respect to PCP cytotoxicity. Upon 48 hrs of exposure, the chemical dose required to cause 50% reduction in cell viability (LD50) was computed to be 1,987.0 +/- 9.6 microg PCP/mL. The NOAEL and LOAEL were 62.5 +/- 10.3 microg PCP/mL and 125.0+/-15.2 microg PCP/mL, respectively. At lower levels of exposure, PCP was found to be mitogenic, showing a strong dose- and time-dependent response with regard to cell proliferation. Western Blot analysis demonstrated the potential of PCP to cause endocrine-disrupting activity, as evidenced by the up regulation of the 125-kDa vitellogenin protein the hepatocytes of male channel catfish.

Subchronic administration of technical pentachlorophenol to lactating dairy cattle: immunotoxicologic evaluation

Eight lactating Holstein-Friesian dairy cattle were randomly allotted as pairs to eight a control or a treatment group fed technical pentachlorophenol (penta) from 6 +/-1 wk postpartum for about 135 d (0.2 mg/kg.d for 75-84 d followed by 2.0 mg/kg.d for 56-62 d). Jugular blood was drawn periodically for immunologic studies. Leukocyte differentials and lymphocyte subpopulations (e.g., T and B cells) were enumerated for each blood specimen. Several in vitro and in vivo assays were conducted to evaluate lymphocyte functions, including (1) quantitation of serum immunoglobulins G, M, and A; (2) induction of blastogenesis in vitro, using concanavalin A and leukoagglutinin as mitogens; (3) measurement of extent of skin reaction to injected purified protein derivative in BCG-sensitized cattle to evaluate delayed hypersensitivity; and (4) quantitation of antibody formation in response to injected sheep red blood cells. Neutrophil function was evaluated by latex particle phagocytosis and chemiluminescence. The results showed no statistically significant differences between control and pent-treated cattle during eigher treatment period. Also, no histopathologic changes were noted in lymphoid tissues including spleen, thymus, and lymph node.