Toxic chemicals: A barrier to safe drinking water

Nonylphenol and its ethoxylates in drinking water: A health challenge

Water treatment facilities are incapable of removing many chemical compounds and need to be upgraded (Image: PxHere)

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22 Jun 2021, 10:52 am

5 min read

A drinking water quality, testing, monitoring and surveillance framework was released by the Ministry of Jal Shakti in March 2021 as a part of the government’s flagship Nal se Jal scheme. The scheme aims to provide piped water supply to each and every rural household by 2024. The drinking water quality framework developed by the Jal Jeevan Mission in partnership with the Indian Council of Medical Research will have an automated data flow of water sample test results to assure the safe supply of drinking water.

However, there is no regulation in the country on the use of deadly chemicals such as nonylphenol that is slowly making their way into our drinking water system. This endocrine-disrupting chemical is largely used in the production of nonylphenol ethoxylate which is “extensively used as consumer products e.g., surfactants, detergents, wetting agents, dispersants, defoamers, de-inkers, antistatic agents and in other industrial applications,” as per a recent report by Toxics Link, an Indian environmental research and advocacy organization.

“Generally, nonylphenol ethoxylates break down to nonylphenol in the natural environment and enter into the ecosystem. They further enter the food chain, where they bio-accumulate and can pose serious environmental and health risks. Research studies across the globe have confirmed environmental and health impacts associated with nonylphenol and nonylphenol ethoxylates,” says the report.

“Nonylphenol and nonylphenol ethoxylates are not produced naturally, and their presence in the environment is a consequence of anthropogenic emissions. Wastewater treatment, landfill and sewage sludge recycling have been found to be the three major contributors of nonylphenol and nonylphenol ethoxylates in the environment. There are also studies which show the leaching of nonylphenol from plastic bottles to water,” says the report.

Several Indian studies such as Selvaraj et al., (2014) and Raju et al., (2018) clearly highlight that discharge of inadequately/untreated domestic and industrial wastewater are the major nonylphenol sources in the aquatic environment. Some toxicity studies have also confirmed the lethal impacts of nonylphenol on fish and other aquatic organisms even at low concentrations. This raises serious concerns about the level of contamination in surface waters in India.

According to the classification by Bartoni, surface waters with nonylphenol content less than 1 μg/L were considered as poorly contaminated, 1–10 μg/L as contaminated, and greater than 10 μg/L as highly contaminated.

Detergents, a source of contamination

As nonylphenol is widely present in detergents and river waters, there is a high possibility that the drinking water is also contaminated with nonylphenol and its ethoxylates. Earlier in 2019, Toxics Link had conducted a study Dirty Trail: Detergent to Water Bodies that revealed the wide use of nonylphenol in detergents. As a part of the study, water samples were collected from various rivers that confirmed the presence of high nonylphenol concentration.

The nonylphenol concentrations in the river water samples ranged from 9.2 –41.3 mg/L. The highest concentration was detected in Bandi River (41.3 mg/L) in Pali, Rajasthan which is a known textile hub of the country indicating excessive use of nonylphenol in textile industries.

The Bureau of Indian Standards (BIS) has set standards for phenols (phenolic compounds expressed as phenols) in drinking water (0.001 mg/L) and surface water (5 mg/L). The methods of sampling and test for phenols are given in IS 3025 (Part 43): 1992 (Reaffirmed 2003). However, there are no specific standards for nonylphenol or nonylphenol ethoxylates in drinking water and surface water or regulations on its use in surfactants and other consumer products.

Assessment of drinking water

In the present study, Toxics Link conducted a detailed assessment of drinking water samples. Fifteen drinking water samples were collected from different parts of India and sent to Shriram Institute of Industrial Research, New Delhi for analysis.

Sampling locations

Nonylphenol was detected in all the drinking water samples, irrespective of the source, in high concentrations compared to previous studies carried out globally. High concentrations were even detected in the drinking water samples collected after treatment at the point of use. There is a possibility that the complete removal of nonylphenols does not take place in the existing water treatment plants in India and the treatment units need to be upgraded.

Its concentration ranged from 29.1–80.5 μg/L and the highest concentration was found in the borewell water collected from Bathinda, Punjab (80.5 μg/L). The lowest concentration was found in the government supply water from Indraprastha, New Delhi (29.1 μg/L).

High concentrations were even detected in the drinking water samples collected after treatment at the point of use (i.e., filtration or RO treatment before drinking). Therefore, drinking water can be a major route of human exposure to nonylphenol.

Results and discussion

Nonylphenol detected in household water supplied by the local government water supply agencies may indicate that the water treatment facilities in those regions are incapable of removing these compounds and need to be upgraded.

There is no study monitoring the concentrations of nonylphenol and nonylphenol ethoxylates in drinking water in India. However, some studies were conducted in other countries to determine nonylphenol concentrations in drinking water. Nonylphenol concentrations from the present study were compared to those global studies. The results clearly indicate the extensive use of nonylphenol in India and the lack of nonylphenol removal in existing water treatment facilities in India.

One of the possible other sources may be leaching of nonylphenol from household pipes. Nonylphenol concentrations were detected in tap water from households using PVC pipes. However, the concentrations were found to be strongly affected by the contact time of water with the pipes and ambient temperature. Additional studies are warranted to assess the potential leakage of nonylphenol from household pipes.

Nonylphenol levels from the present study were also found to be much higher than those reported in earlier studies. Nonylphenol contamination in groundwater has been mainly associated to landfill leachate, water from agricultural land, or seepage of septic tanks and sewer systems. Long-term irrigation with reclaimed water can lead to infiltration and migration of nonylphenol in groundwater and is also one of the possible sources.

Three samples collected in the present study were treated at the point of use. Nonylphenol detection in the treated water samples was also found to be high, clearly demonstrating that installed household treatment units were not capable of removing nonylphenol. Therefore, studies must be carried out to evaluate the performance of household RO and filtration systems in removing nonylphenols and other emerging contaminants.

There is a necessity of revising BIS testing protocols, and methods which are presently underestimating phenolic concentrations in the samples.

Conclusion

It is necessary to monitor the presence of nonylphenol and nonylphenol ethoxylates in drinking water as well to bring about a possible revision of drinking water standard at par with the global standard specific to nonylphenol and nonylphenol ethoxylates.

This study identifies the risks of continued usage of nonylphenol and recommends the development of an action plan to phase out the chemical from the country as soon as possible. The chemical can be prohibited from use in products including detergents as suitable alternatives are widely available. The study also highlights the need to revise the Bureau of Indian Standards (BIS) testing protocols for analyzing specific phenolic compounds and come up with specific standards for nonylphenol and nonylphenol ethoxylates in water.