Using of ethylenediaminetetraacetic acid (EDTA) and synthetic surfactant increase the chemical contamination in water. The co-phytotoxicity of EDTA (0-20 mg/l) and 3 synthetic surfactants; Triton X-100 (0-10xCMC) Tween 80 (0-10xCMC) and sodium dodecyl sulfate (SDS) (0-2 x CMC) on the growth of 2 duckweeds spirodela polyrrhiza and Lemma perpusilla were studied for 3 days. The results showed that the surfactant were phytotoxic on the growth of both plants while EDTA was not. SDS was the most toxic to plant especially on all chlorophyll content. Triton X-100 was only toxic to the growth of L. perpusilla and weight of S. polyrrhiza. Tween 80 was less or the least toxic to both plants. This surfactant only decreased chlorophyll a and total chlorophyll content of S.polyrrhiza and L. perpusilla. There was not any interaction between EDTA and surfactant on most toxicity tests. With these results synthetic surfactant contamination should be more concerned than co-contamination with EDTA.

The effects of plant growth regulators alone or in combination on Hexachlorocyclohexane (HCH) phytotoxicity were studied. Waxy corn seeds were immersed in different plant growth regulators that are 1) 2 mg/l Indolebutyric acid (IBA) 2) 2 mg/l Thidiazuron (TDZ) 3) 2 mg/l Gibberellic acid (GA3) 4) 1 mg/l IBA + 1 mg/l TDZ 5) 1 mg/l TDZ + 1 mg/l GA3 and 6) 1 mg/l IBA + 1 mg/l GA3 then sawn in 30 mg/kg HCH-contaminated soil or non-contaminated soil for 10 days. All plant growth regulators could enhance shoot and root dried weight of waxy corn seedlings in non-contaminated soil. Only 2 mg/l GA3 could enhance root length of waxy corn seedlings in non-contaminated soil. In HCH-contaminated soil only 2 mg/l TDZ could increase shoot dried weight of waxy corn seedlings. Also 2 mg/l IBA or 1 mg/l IBA and1 mg/l GA3 could increase root fresh weight of waxy corn seedlings. The exposure with HCH in soil did not affect to shoot and root tissue even though the growth of shoot and root were inhibited. However the exposure with HCH and receive exogenous plant growth regulator induced aerenchyma formation in cortex and pith of waxy corn root.