It wasn’t that long ago that the pandemic snarled shipments of toilet paper the world over. Now, U.S. President Donald Trump’s tariffs are threatening disruption once again.

Suzano SA is the world’s largest exporter of pulp — the raw material for products including bath tissue. The company has seen that export levies have led to a decline in shipments of the product from Brazil to the US, Chief Executive Officer João Alberto de Abreu said in an interview. The Sao Paulo-based company is now passing tariff costs on to US buyers, he added.

While it’s too early to tell how severely tariffs will shake up the paper supply chain, the impact on pulp is just the latest example of how trade spats threaten to upend the normal flow of global shipments for essential goods. Brazil’s exports of bleached hardwood pulp, the type produced by Suzano, to the US fell 20% from a year earlier in April, according to government data.

Suzano shares slid as much as 4.3% in Sao Paulo trading on Friday, hitting the lowest intraday level since June. The stock is down almost 20% this year.

The uncertainty generated by US tariffs have impacted consumer sentiment and negotiations, Leonardo Grimaldi, an executive vice president at Suzano, said during a call with analysts.

“Since costumers are still struggling to forecast how tariffs can affect their production plans, either directly or indirectly, all pulp buyers and sellers” are in price-discovery mode, Grimaldi said.