Researchers at Greenpeace have reprimanded Apple for releasing products made with chemicals which can reportedly have adverse effects on the development of male reproductive organs.

Greenpeace, which has taken exception to Apple's green credentials several times in the past, claims that the headphone cables that ship with iPhones and iPods feature levels of chemicals called phthalates that would be classified in Europe as being "toxic to reproduction".

Phthalates are used to give iPhone and iPod headphones cords their flexibility. Greenpeace argues that these chemicals also have the ability to interfere with sexual development in mammals, particularly males.

Exposure to phthalates, according to research published in the Wall Street Journal, can affect male development in the womb, with effects ranging from undescended testes at birth to low sperm counts later in life.

Concentrations of phthalates are therefore banned in categories of toys and other childcare items in Europe.

The presence of phthalates in Apple's products has met with the ire of the US Center for Environmental Health which, according Wired, is threatening to initiate a "citizen enforcement" lawsuit against Apple over the issue.

The not-for-profit advocacy group is reportedly demanding Apple recall its products and take measures to warn users about the presence of the chemical in future releases.

However, the iPhone's overall green record is largely favourable, according to Greenpeace. The group found that the device is for the most part environmentally sound -- with no trace of harmful metals such as cadmium or mercury and very low concentrations of lead and chromium.

Greenpeace nonetheless recommended that Apple address the levels of bromine, antimony, chlorine and phthalates in future products.

"If Apple really wants to reinvent the phone, it needs to design out all hazardous substances and materials from its handsets and peripherals," the report stated.