Hormetic dose responses induced by lanthanum in plants

Area of Science:

• Environmental Science
• Plant Biology
• Toxicology

Background:

• Rare earth elements (REEs) are accumulating in the environment.
• Lanthanum (La), an REE, is of increasing environmental concern.
• Understanding La's effect on plants is crucial for environmental risk assessment.

Purpose of the Study:

• To evaluate the occurrence and characteristics of La-induced plant hormesis.
• To quantitatively and qualitatively assess La's dose-response effects on plants.
• To provide insights for improving experimental designs assessing low-dose effects.

Main Methods:

• Literature review of peer-reviewed studies on La and plant responses.
• Quantitative and qualitative assessment of 703 La-induced hormetic concentration/dose responses.
• Analysis of factors influencing hormetic responses, including substrate pH and exposure duration.

Main Results:

• Identified 703 La-induced hormetic responses in plants.
• Maximum biological response typically below 150% of control (geometric mean 142% at 56 μM).
• Geometric mean NOAEL was 249 μM, with a MAX:NOAEL distance commonly below 5-fold (mean 4.5-fold).

Conclusions:

• Low La concentrations can induce hormesis in plants.
• Hormetic responses are influenced by experimental conditions like substrate pH and exposure time.
• Findings aid in understanding La's environmental impact and refining low-dose effect studies.