BEIRUT: Investigators from the global chemical arms watchdog finally collected samples on Saturday from the site of a suspected gas attack in Syria two weeks ago, after security concerns delayed their probe.

“The samples collected will be transported to the OPCW Laboratory in Rijswijk and then dispatched for analysis to the OPCW’s designated labs,” Organisation for the Prohibition of Chemical Weapons (OPCW) said in a statement, adding it could plan another visit.

Russia’s foreign ministry had earlier announced the inspectors reached Douma after guarantees by Syria and its own forces, and said it expected them to carry out an “impartial investigation”.

Moscow, a key ally of President Bashar al-Assad, has said its own probe into the events in Douma found no traces of chemical use. Assad’s government, too, has repeatedly denied using toxic weapons, and accused the West of “fabricating” the claim to justify bombing Syria.

Analysts say that if toxic chemicals were used, OPCW inspectors would still be able to find important traces in clothes, walls, rocks and soil in Douma, although their potency decreases with time.

“Nerve agents like sarin can be present in the environment for many weeks after use and particularly if you look near the site where a weapon has exploded,” said Alastair Hay, professor of environmental toxicology at the University of Leeds.

Crucial evidence can also linger in victims’ blood, urine and organs. “Autopsy samples, if available, will provide invaluable evidence and nerve agents can be found in many organs,” Hay said.

The “White Helmets”, a Syrian rescue force that works in opposition-held areas, said it had given the OPCW details on the burial site of the Douma victims. But a top official from Jaish al-Islam, the rebel group that controlled Douma during the alleged chemical attack, accused the regime of raiding the graves.

The OPCW does not have a mandate to establish who is responsible for chemical attacks. The joint OPCW-UN taskforce that did was shut down by Russia last year after it blamed Syria’s regime for another gas attack.

Experts say it may take between two to three weeks to analyse evidence collected in Douma.

Published in Dawn, April 22nd, 2018