Consumer affairs groups in Japan are concerned over a rash of incidents involving smartphone chargers and cables.
Nearly 100 cases of smoke, fire or overheating involving chargers have been recorded by the Consumer Affairs Agency over the past year.
Some incidents have involved injuries. For instance, one person was slightly injured in a fire apparently linked to a portable phone charger in Saitama Prefecture outside Tokyo last month.
While the cause of the fire is still being investigated, the Topland charger unit, which was sold at convenience stores in Japan, was subject to a fire hazard recall issued in July that involved some 224,000 units.
The chargers housed lithium-ion batteries, which have been implicated in overheating and fire cases including the incidents that led to the grounding of the Boeing 787 Dreamliner aircraft fleet last year. In 2006, Sony recalled tens of thousands of laptop PC batteries due to fire risks.
The causes of the recharger incidents vary and are being investigated, a spokeswoman for the Consumer Affairs Agency said.
The government-affiliated National Institute of Technology and Evaluation (NITE) recently warned consumers that recharging cables for smartphones and tablets can also dangerously overheat.
NITE has recorded 48 cases in which cables, including micro USB connectors, overheated during a five-year period. Ten cases involved minor injuries to users and in 25 cases there was additional property damage besides the units in question.
"The terminals inside the connectors can become twisted or deformed and interrupt the flow of current," a spokeswoman for NITE said in explaining one of the causes. "Sweat, liquids and small debris or dust can also cause short circuits and fire."
The institute has mounted a public awareness campaign telling people not to store cables in dusty, moist areas.
It has also produced videos including one showing a smartphone charging cable that has been intentionally bent at the terminal and then forcibly straightened. It begins to emit smoke when current is applied.