The Mobil Research and Development Corporation has submitted summarized results from several laboratory studies of dimethyl hydrogen phosphate (CAS No. 868-85-9). According to the submitter, the chemical was found to be positive in two of five short-term mutagenicity screening tests. In addition, the submitter reported that cataracts and 'other toxic effects' were observed in rats exposed (subacutely) to dimethyl hydrogen phosphate at high vapor concentrations (i.e., 119 and 198 ppm). Milder forms of lens opacities were reportedly observed in rats that although no clinical cataracts were found in a previously performed ophthalmological study of plant employees, including those involved with the manufacture of dimethyl hydrogen phosphate, a reanalysis of the original data will be conducted 'to determine whether there may be a statistically significant number of subclinical opacities among the dimethyl hydrogen phosphate segment of the plant population'.