Nine-volt battery batteries were formerly made in this size. They had higher capacity than the then-standard carbon-zinc types, a nominal voltage of 8.4 volts, and very stable voltage. Once used in photographic and measuring instruments or long-life applications, they are no longer manufactured as mercury is highly toxic and accumulates in the ecosystem, posing a risk to humans and wildlife. Most battery voltage testers and chargers that can also test nine-volt need another snap clip to hold the battery, while cylindrical batteries often share a holder that may be adjustable in size. Because of the proximity of the positive and negative terminals
Global waste trade may be more vulnerable to the dangerous effects of the hazardous waste trade, and are particularly at risk from developing health problems. The methods of disposal of these toxic wastes in developing countries expose the general population (including future generations) to the highly toxic chemicals. These toxic wastes are often disposed of in open landfills, burned in incinerators, or in other dangerous processes. Workers wear little to no protective gear when processing these toxic chemicals, and are exposed to these toxins through direct contact, inhalation, contact with soil and dust, as well as oral intake of contaminated locally produced food