Three sisters in the city of Kyoto suffered mild numbness and trembling Friday after eating cakes from a pastry shop, the latest of several recent poisoning scares in Japan.

Michiko, Wakako and Natsue Nishimoto were taken to a hospital in Kyoto, 230 miles southwest of Tokyo, but released later after showing no serious symptoms.The cakes were brought by a friend to celebrate Natsue's birthday. But they tasted "bitter" and "strange," the sisters told police, who were checking the pastries for toxic substances.

A series of poisonings in recent weeks has raised fears of future copy-cat incidents.

In July, four people died from eating curry laced with cyanide and arsenic at a festival in southwestern Japan. Two weeks later, 10 people in northern Japan suffered vomiting and numbness after drinking tea containing a toxic sodium compound.

Earlier this week, a man was arrested in northern Japan for allegedly trying to blackmail a confectionery shop by threatening to lace its cakes with salmonella.