Friday, 19 July 2019

Indian Scientists Develop Database Of Everyday Chemicals Harmful To Human Health

The chemical substances have been classified in seven broad categories - consumer products, agriculture and farming, industry, medicine and healthcare, pollutants, natural sources and intermediates - and 48 sub-categories.


The research team at IMSc, Chennai
In our daily lives, we get exposed to dozens of chemicals either through products we use or consume as well as through exposure to the environment. Such chemicals are present in consumer products, pesticides and insecticides, cosmetics, drugs, electric fittings, plastic products, electric and electronic devices and so on. Many of them contain substances harmful to human health and have been subjected to research over the years.

Now, Indian scientists have developed a comprehensive database of such chemicals belonging to a particular category known as endocrine disrupting chemicals or EDCs. These chemicals can interfere with hormones in human body, causing adverse health effects related to development, growth, metabolism, reproduction, immunity, and behaviour. The World Health Organisation (WHO) considers them as ‘chemicals of emerging concern.’ EDCs are only a subset of toxic chemicals in our environment that affect the hormonal system.

The database is not a simple listing of chemicals but a comprehensive catalogue of research studies that focused on impact of these chemicals on health. These studies have been done in rodents and humans. The database has been developed by an inter-disciplinary team of researchers at the Chennai-based Institute of Mathematical Sciences (IMSc).

Over 16000 scientific studies about EDCs and evidence of their ability for endocrine disruption were mined. Based on this, 686 potential hormone-disrupting chemicals have been identified with evidence of causing hormonal changes in 1796 research articles specific to humans or rodents. 

The first version of 
Database of Endocrine Disrupting Chemicals and their Toxicity profiles’ (DEDuCT) has been published and it is freely accessible.

The chemical substances have been classified in seven broad categories - consumer products, agriculture and farming, industry, medicine and healthcare, pollutants, natural sources and intermediates - and 48 sub-categories. Almost half of the chemicals listed in the database fall in the ‘consumer products’ category. Of 686 potentially harmful chemicals identified in the database, only 10 are in the Safer Chemicals Ingredients List (SCIL) of the US Environment Protection Agency.

All detailed information such as which EDC causes endocrine disruption, at what dose and if the study has been in animals or humans, is available in a searchable mode. The dose information is critical since some of these chemicals can result in adverse impacts even at very low doses, while in some case it may not be so. One can also get chemical structure, physico-chemcial properties and molecular descriptors of the chemicals.

“We identified EDCs based on published experimental evidence about their ability to cause endocrine disruption, and compiled observed adverse effects along with dosage information. Adverse effects have been classified further into seven systems-level changes. This information will facilitate toxicology research towards understanding the mechanism of endocrine disruption by these chemicals,” explained Areejit Samal, scientist who led the research team in the computational biology group at IMSc, while speaking to India Science Wire.

The information will be useful to regulatory agencies, health authorities and industry. In addition, it can be used for developing machine learning-based predictive tools for EDCs. The database is more comprehensive than other available resources on EDCs and contains extensive information on dose which other databases do not have, researchers said.

Besides toxicology experts and other scientists, the database can also be useful for general public. “This resource can help raise awareness against indiscriminate use of EDCs in daily life. People can browse these chemicals by environmental source in our user-friendly database or can search if chemicals in products they use are EDCs based on our compilation,” added Samal.

The IMSc group has earlier developed an online database of phytochemicals present in Indian herbs that can potentially be developed into drugs.

The research team included Bagavathy Shanmugam Karthikeyan, Janani Ravichandran, Karthikeyan Mohanraj, R.P. Vivek-Ananth, Areejit Samal. A report on the database is to be published in scientific journal Science of the Total Environment.

Monday, 8 July 2019

Indian Scientists Develop 'Black Gold' - A Wonder Material

Scientists at the Mumbai-based Tata Institute of Fundamental Research (TIFR) used gold nanoparticles and by rearranging size and gaps between them developed a new material which has unique properties such as capacity to absorb light and carbon dioxide. 


Prof. Vivek Polshettiwar with research team at TIFR, Mumbai
Indians are fascinated with gold, making India one of the largest consumers of the yellow metal globally. Now Indian scientists have tinkered with the chemistry of the material and turned it into ‘black gold’ which they say can be potentially used for applications ranging from solar energy harvesting to desalinating seawater.

Scientists at the Mumbai-based Tata Institute of Fundamental Research (TIFR) used gold nanoparticles and by rearranging size and gaps between them developed a new material which has unique properties such as capacity to absorb light and carbon dioxide. Gold does not have these properties, therefore ‘black gold’ is being called a new material. In appearance it is black, hence the name ‘black gold.’

The findings have been announced in Chemical Science, a scientific journal published by the Royal Society of Chemistry.

“We have not doped gold nanoparticles with any other material or added other materials. We varied inter-particle distance between gold nanoparticles using a cycle-by-cycle growth approach by optimizing the nucleation-growth step, using dendritic fibrous nanosilica, whose fibers were used as the deposition site for gold nanoparticles,” explained Vivek Polshettiwar, who led the research team, while speaking to India Science Wire.


One of the most fascinating properties of the new material is its ability to absorb the entire visible and near-infrared region of solar light. It does so because of inter-particle plasmonic coupling as well as heterogeneity in nanoparticle size. Black gold could also act as a catalyst and could convert carbon dioxide into methane at atmospheric pressure and temperature using solar energy.

“If we develop an artificial tree with leaves made out of back gold, it can perform artificial photosynthesis, capturing carbon dioxide and converting it into fuel and other useful chemicals,” added Prof Polshettiwar. The efficiency of conversion of carbon dioxide into fuel, at present, is low but researchers believe it could be improved in future.

In order to study solar energy harvesting ability of the new material, researchers dispersed it into water and exposed the solution to light for one hour and the temperature of the solution was measured. The temperature of the solution with pure silica spheres rose to 38 degrees while the ones with different concentrations of black gold rose to 67 to 88 degrees. The maximum increase in temperature was attributed creation of thermal hotspots due to the heterogeneity of the particle sizes as well as optimum inter- particle coupling.

Researchers said the material can be used as a nano-heater to covert seawater into potable water with good efficiency. “Our results indicate the potential application of black gold in purification of seawater to potable water via steam generation using solar energy under atmospheric reaction conditions,” according to the researchers.

Kabeer Jasuja (Indian Institute of Technology – Gandhinagar), who is not connected with the study, commented that "It is amazing to see these elegantly designed assemblies of gold nanoparticles could function as artificial leaves and capture the solar energy. This study is a significant step in current efforts towards reducing carbon footprint. It would be promising to see how the synthesis of these colloidosomes can be scaled up in the future."

The research team included Mahak Dhiman, Ayan Maity, Anirban Das, Rajesh Belgamwar, Bhagyashree Chalke and Vivek Polshettiwar (TIFT); Yeonhee Lee, Kyunjong Sim and Jwa-Min Nam (Seoul National University). The study was funded by the Department of Science and Technology (DST) and the Department of Atomic Energy (DAE).