Dumplings at Hung Ming-he’s food stall at the Xizhou Public Market, one of the oldest traditional food markets in Taipei, on April 8. | An Rong Xu / The New York Times

TAIPEI – Plastic producers in Taiwan have scrambled to secure new supplies since the war in Iran disrupted petrochemical flows and tightened availability. Some producers have turned to the United States to purchase liquefied petroleum gas, another petrochemical used to make plastic. Others have sourced plastic goods from China, where many Taiwanese manufacturers have long-standing relationships.

Taiwan’s main plastic manufacturer, Formosa Petrochemical, imports two-thirds of its naphtha, the petrochemical used to make plastic, most of it from the Middle East. But in early March, the tankers carrying those supplies from the Persian Gulf stopped arriving.

The shortage forced Formosa Petrochemical to shut one of its two production lines.…