Loures Hands Out 20,000 Drink-Testing Wristbands, and the Mayor Says There Was No Incident Behind It

A council technician stood at the gate of the Parque Papa Francisco in Loures on Saturday evening handing out wristbands to anyone going in to see Carl Cox. Five thousand of them, the first tranche of twenty thousand the Câmara Municipal de Loures (Loures Municipal Council) has bought. Put a drop of your drink on the reactive patch, and if the patch changes colour you have been told something about what is in the glass.

The council announced the campaign on Thursday. It is, as far as anyone involved can establish, the first time a Portuguese municipality has bought drink-testing wristbands in bulk and given them away at the door of a concert.

The most interesting thing the mayor said about it is that nothing happened to prompt it.

"People have already asked me whether this initiative is a reaction to a set of situations that may have occurred, but no," Ricardo Leão (PS) told the news agency Lusa. "We have no record of any occurrence. Even so, we take the view that it is a very good measure."

What the council bought, and for how much

The scheme is a three-way arrangement between the câmara, the Polícia de Segurança Pública (Public Security Police, PSP) and Desert Rain, the promoter running the concert. Loures has form for cheap, high-volume health interventions of this shape: it was one of the four municipalities covered when free walk-in HIV and hepatitis tests went into 58 Lisbon-area pharmacies in the spring. The total spend is 22,000 euros, split equally between the council and the promoter.

Twenty thousand wristbands for 22,000 euros is 1.10 euros each. Half of that is public money, so the cost to the Loures taxpayer is about 55 cents per wristband. Whatever else this is, it is not an expensive piece of municipal policy, and the mayor said as much.

"It is not about the financial amount. It is about the importance and the effect it may come to have in the rest of the country, and the sense of safety we all gain from what is an act of prevention," Leão said. He also said he was sure other councils would copy it.

The remaining fifteen thousand wristbands are to be distributed across the rest of 2026 at other events. The council says it will assess the results at the end of the year and may run the campaign again in 2027.

The chemistry, and where it comes from

The wristbands are made by Celentis, a Spanish company. The underlying detection chemistry came out of a Portuguese laboratory: it was developed in 2025 by Carlos Lodeiro Espiño, a professor in the chemistry department of the Faculdade de Ciências e Tecnologia da Universidade NOVA de Lisboa (NOVA School of Science and Technology, NOVA FCT) and a researcher at the LAQV-REQUIMTE unit, working with the University of Valencia and with Celentis. NOVA FCT says the collaboration has produced a joint patent and two scientific papers.

It is worth being precise about the institution, because several reports on Saturday placed the work at the University of Lisbon. It is the Universidade NOVA de Lisboa, a different university, and the faculty concerned is in Caparica.

The user instruction is simple. A drop of the drink goes onto one of the reactive zones on the band. According to Celentis, gamma-hydroxybutyrate turns the patch dark green; burundanga, ketamine and cathinones turn it from pale yellow to orange. The reaction is described as immediate. The company puts the detection floor for GHB at 0.1 milligrams per millilitre. The bands are printed on Tyvek, are waterproof and sweat-resistant, and come in three widths.

NOVA FCT adds two details the wire coverage did not carry. The sample does not have to be poured: a finger dipped in the drink, or a small quantity of saliva, will do. And the band is reusable for up to five days, or until it returns a positive result. A positive consumes the band.

One drug, or five

There is a gap between how the campaign was described this week and what the laboratory says the chemistry does, and it is worth setting out plainly because both statements are accurate in their own terms.

The council's announcement, and the wire copy that followed it, described the wristbands as detecting GHB, "gamma-hydroxybutyric acid, popularly known as the G drug or the rape drug", whose effects include loss of coordination, dizziness, amnesia and loss of consciousness. That is the headline substance and it is what the campaign is being sold on.

The developers describe a wider range. NOVA FCT lists GHB, scopolamine (burundanga), methamphetamines, ketamines and cathinones. Celentis splits the response by colour: dark green for GHB, and a yellow-to-orange shift for the burundanga, ketamine and cathinone group. Two different colour channels, one band.

Neither account is wrong. The council is describing the substance the campaign is aimed at; the laboratory is describing the sensor's range. Anyone handed a band at a gate is better served by the second description, because it tells them what a colour change actually means, and that an orange patch and a green patch are saying different things.

What a colour-change patch can and cannot tell you

These are screening aids. They are not laboratory tests, and there are three limits worth holding on to.

• They test the drop, not the drink. A colorimetric patch reads what is on the patch. A drink that has been spiked unevenly, or spiked after the sample was taken, is not covered by an earlier negative.
• They only look for what they are built to look for. The list above is the list. The most common substance used to incapacitate someone in a bar is alcohol itself, in quantity, and no reagent patch is going to flag that. Nothing in this campaign changes what a very strong drink does.
• A negative is not a clearance. Detection floors exist, which is why Celentis publishes one. A concentration below the threshold reads the same as a clean drink.

None of that is an argument against handing them out. It is an argument for reading the band as one piece of information among several, which is roughly what a 55-cent public health intervention can reasonably be expected to be.

Why a council is doing this at all

Portuguese municipalities have limited tools in this area. Licensing hours and policing are the usual two, and both are blunt: Albufeira spent the summer closing its bars earlier and found out how contested that gets. Buying a consumable and giving it away at a gate is at the other end of the scale. It costs almost nothing, it requires no by-law, and it puts something physical in the hands of the people the risk actually falls on.

It also sits in a market where what is in a glass, or in a wrap, is frequently not what it was sold as. A violent August weekend in Lisbon and Porto turned on a fake-drug trade the law still cannot reach, precisely because selling a harmless powder as cocaine is not a drug offence. A reagent that tells you what a substance is, rather than what someone said it was, is useful in that environment for reasons beyond the one the campaign is named after.

It also has the property, unusual in municipal safety spending, of being measurable. Twenty thousand bands go out; the council can count how many are taken and, if anyone reports a positive, it will know. The mayor said the campaign will be evaluated at the end of the year. That evaluation is the thing to watch, because at the moment the honest position, which Leão stated himself, is that Loures has no recorded case.

What this means for expats

• You do not have to be a Loures resident to be handed one. The distribution point is the gate of the venue, not the council's offices, and the criterion is that you want one. The Parque Papa Francisco sits in the Loures municipality on the northern edge of the Lisbon metropolitan area, and its crowd is regional rather than local.
• Read the colour, not just the change. Green and orange mean different families of substances on these bands. If you take one, look at what the printing on it says before you need it, not after.
• The bands are reusable until they are not. Up to five days, or one positive. Do not assume the one in your pocket from last weekend is still live.
• If you think you have been spiked, this is a hospital matter, not a wristband matter. Go to an emergency department and say what you suspect. Detection windows for these substances in the body are short, which is why the timing of the sample matters far more than the colour of a patch. GHB in particular clears quickly.
• Reporting it is separate from treating it. The PSP is a partner in this campaign, which makes the reporting route unusually clear: the same force that helped hand out the band takes the complaint.
• Expect this to spread. The mayor's stated ambition is that other councils copy the scheme, and at this price they can. If you live in one of the Lisbon or Porto ring municipalities with a large summer events programme, it would not be surprising to see the same bands at a gate near you in 2027.

The campaign runs to the end of the year. Fifteen thousand bands are still in the box, and the council has not yet said which events they go to. What it has said, and this is the part that will decide whether the idea travels, is that it will publish an assessment. Twenty thousand wristbands handed out against a starting point of zero recorded incidents is either a cheap piece of prevention or a cheap piece of reassurance, and only the evaluation will separate the two.