When an idol made of Plaster of Paris is immersed in the water, it changes form to gypsum, thus adding a large amount of material to the water that breaks down very slowly, while adding to the hardness of water, both of which deteriorate the life carrying capacity and quality of the water thereby causing irreversible environmental effects on the coastal ecology or the eco-system of any water body, which in turn causes adverse environmental effects;
Chemical paints and dyes
In terms of health impacts, paints are a greater source of hazard and most of those used for decorating idols are chemical-based. They contain heavy metals like mercury, cadmium and lead, which are neurotoxin (nerve poison) and nephrotoxin (poison to kidneys).
These metals are bio-accumulative, meaning that once they enter marine life forms like fish; they pass through the food chain and end up in the food that we eat. Incidentally, the brighter the colour, the greater is its toxicity. Red, blue, orange and green colours are known to have higher content of mercury, zinc oxide, chromium and lead.
The safe levels of these chemicals in natural environment are reported in literature in the unit of ppb - parts per billion, which is 1000th part of 1 milligram per liter of water. Sometimes the permissible levels of these toxic metals are reported as one millionth part of a milligram in one liter of water i.e. ppt – parts per trillion!
Therefore, this implies that -one drop in a 20-acre lake can make the fish poisonous to the birds, animals, and people that eat them.
An example:
A study in 2001, revealed an alarming increase in presence of heavy metals in the Hussainsagar Lake (Hyderabad) following immersions. The study showed that subsequent to Ganesh-idol immersions, the concentration of these metals Calcium, Magnesium, Iron, Lead, increased perceptibly. The level of arsenic, a noxious trace element, had increased nine-fold in the lake water after the idol immersion, compared to its Bureau of Indian Standards (BIS), Indian Council of Medical Research (ICMR) standards.
The concentration of mercury was found to be alarmingly high in the lake water. It increased by five to six hundred times in the lake water compared to the specifications of desirable limits set by BIS and ICMR standards.
The various paraphernalia immersed along with the idols and its impact is given below:
| Sr.No | Material contributed by immersion | Impact on the aquatic body |
| 1 | Plaster of Paris | Increases dissolved solids, contribute metals and sludge |
| 2 | Decoration material viz. clothes, polish, paint, ornaments cosmetic items etc. | Contributes suspended matters, trace metals (Zinc, lead, iron, chromium, arsenic, mercury etc.) metalloids and various organic and inorganic matter, oil & grease etc. |
| 3 | Flowers, Garlands, oily substance | Increase floating suspended matter organic contamination, oil & grease and various organic and inorganic matter. |
| 4 | Bamboo sticks, Beauty articles | Big pieces get collected and recycled while small pieces remain floating in water or settled at the river bottom inhabiting river flow. |
| 5 | Polythene bags/plastic items | Adds to the hazardous material and chokes the aquatic life |
| 6 | Eatables, food items etc. | Contributes oil and grease, organics to water bodies. |
All the figures quoted above and the data has been taken from the report-
- Preventive Environemental Management plan for eco-friendly Ganpati festival prepared by Dr. Shyam R Asolekar, Professor & Head Centre for Environmental Science & Engineering Indian Institute of Technology Bombay (IIT-B), 2007.
- ‘Make ganesh Utsav and Durga Puja Toxics free’- a Factsheet on the impacts of eco-friendly idols compiled by Toxics link, Delhi, 2007.
