HONG KONG (AP) — Chanting “No more tear gas,” dozens of Hong Kong families with young children are marching in protest of the government’s handling of protests on the eve of keenly contested local elections.

Riot police have fired more than 9,000 rounds of tear gas since protests began roiling the Chinese territory in June, often in crowded areas and also near schools. The government says there is no evidence of any health risks and refuses to reveal the chemical composition of tear gas.

With police now buying canisters from China, one participant in Saturday’s march, Emily Ku, says she fears tear gas could contain cancer-causing dioxin.

Walking with her 5-year-old daughter, Ku says people are worried about the long-term impact of tear gas.