The objective of this study was to evaluate the usefulness of rat embryo limb bud cell cultures (LBC) for analyzing joint embryotoxic action of chemical contaminants in the environment. The mode of joint action of chemicals in LBC can be visualized using the toxic unit model and an isobole diagram.
The embryotoxicity of nine organochlorine compounds commonly detected in the environment were screened using LBC.These chemicals were p-dichlorobenzene (pDCB), o-dichlorobenzene (o-DCB), p-chloroaniline(pCA), 3,4-dichloroaniline (DCA), tris(2-chloroethyl) phosphate, 2,5-dichlorophenol (DP), 2,5-dichloroanisole (DA), Triclosan (IR) and Triclocarban (TC). The embryotoxicity of binary mixtures of these chemicals were also screened and analyzed using LBC and isobole diagram. Mixture of IR-TC showed additive joint action. Mixtures of pDCB-TCEP and pDCB-pCA showed less than additive joint action for cell proliferation while mixture of pDCB-DP showed less than additive joint action for cell differentiation.
As LBC can assess the joint action for cell proliferation, for cell differentiation and for their ratio of the former to the latter (P/D ratio), LBC is useful for evaluating embryotoxic potential of chemical mixtures.