CHENNAI, India (Thomson Reuters Foundation) - The change in the sanitary pads was first noticed by maintenance staff at the Centre for Development Studies in Thiruvananthapuram a couple of years back.
Suddenly, the traditional method of burying used pads with lots of lime to decompose them was not working - and the pads were just piling up in disposal pits on the leafy campus designed by eco-friendly architect Laurie Baker in the 1970s.
"It took us a while to realise that manufacturers were using increasing amounts of non-biodegradable plastics in the pads," professor J. Devika, who is leading waste management efforts at the centre, told the Thomson Reuters Foundation.
"All efforts to dispose of them were suddenly failing."
The campus committee decided to talk about the problem, breaking the silence around menstruation and holding numerous meetings with reticent students to see how to reduce the waste.
Today the students - both male and female - are part of Thiruvananthapuram's collective effort to "green the red" - a sustainable menstruation project promoted by the city's civic authority.
From vending machines dispensing cotton pads to awareness campaigns and higher disposal fees for girls and women using disposable pads, the city of more than 1.5 million is taking measures to switch to eco-friendly menstruation products.
"In the next one month, we are looking at placing vending machines in schools, colleges and public spaces that will dispense three (cotton) pads of 10 rupees (less than $1)," said Rakhi Ravikumar, deputy mayor of Thiruvananthapuram in Kerala state.
"There are manufacturers willing to partner with us and we are determined to push this through."
In India, women have traditionally used scrap cloth from old saris or towels, folded and held in place by underwear or a string "belt", adding a layer of sand, ash or rice husk for added protection during heavy blood flow.
The scraps are generally used for a couple of months before they are burnt or buried.
As incomes rise for some women, an increasing number are switching to disposable pads, which are also being handed out as part of the government's menstrual hygiene initiative in many states.
A 2016 study by the Tata Institute of Social Sciences on menstrual hygiene management among adolescent girls in India showed that one in five girls disposed their soiled sanitary products in "inappropriate locations".
In urban centres, disposal was mainly through routine garbage disposal and burning, while in rural areas burying and throwing away in public spaces was also common, the study found.
"Safe disposal will become a growing problem across India as more females turn to commercial pads, with the potential for 9,000 tonnes of waste (for 432 million pads) annually," the report stated.
The conversation around menstruation in Thiruvananthapuram is extraordinary, say campaigners, as for many Indian women, especially adolescent girls, menstruation is both "shameful and uncomfortable".
From being barred from religious shrines to dietary restrictions and enforced isolation during their periods to a lack of access to toilets, women continue to face many challenges during menstruation, campaigners say.
"Despite the backward views on menstruation, we felt we could slowly start talking about this in public," said Shradha Shreejaya of the Sustainable Menstruation Kerala Collective.
"As we talked to women we realised that most thought the pads they were using were made of cotton. They were shocked to know that 90 percent of it is plastic, often not sterilised, heavily bleached and almost impossible to dispose of."
Discussion about sustainable menstrual hygiene has slowly picked up in Thiruvananthapuram with women walking up to stalls selling alternative sanitary products and asking about menstrual cups, reusable cloth napkins and cotton pads.
"We are giving women living and working on campus a few months to use up their stock of commercial sanitary pads, after which they will be heavily fined if they continue using them," Devika said, adding that only eco-friendly products would be available on campus, which already sorts and recycles the rest of its garbage.
"It is the only way save this small but astonishingly beautiful campus."
Reporting by Anuradha Nagaraj, Editing by Ros Russell; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking and climate change. Visit www.trust.org