It has been over two-and-a-half years since a draft directive from the Union Health Ministry sought to replace plastic and polyethylene terephthalate (PET) bottles with glass for storing pharmaceutical preparations.
Leaching is a process by which water-soluble substances are washed out from soil, waste or containers (in this case).
Last year, a government study detected toxic materials, including lead, in plastic bottles of cough syrups and other liquid medicines. It concluded harmful substances are released from such bottles and suggested banning the use of such containers to keep drugs.
A ministry source said the finding was endorsed by the country's top statutory authority on standards for medicines - the Drugs Technical Advisory Board (DTAB).
"The DTAB also recommended that plastic and PET bottles should not be used for bottling medicines, especially meant for children and elderly people," the source said.
These findings, which came out in May 2016, were contrary to the findings of another expert panel led by former biotechnology secretary MK Bhan.
The MK Bhan panel had in March that year told the National Green Tribunal there is no conclusive evidence to suggest that use of PET or additive like antimony for pharmaceutical packaging may leach out substances beyond limits that pose a threat to human health.
The study, reported in May 2016, was conducted by the government's All India Institute of Hygiene and Public Health (AIIH&PH).
It had found that four heavy metals - lead, antimony, Di-(2-ethylhexyl) phthalate (known as DEHP) and chromium - had leached into the five pharmaceutical formulations that were tested.
The degree of leaching with antimony, chromium, lead and DEHP from PET bottles grew as temperature increased.
The ICMR has now asked the National Institute of Nutrition, Hyderabad, to plan and conduct the study.