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New Hampshire Department of Environmental Services

Mercury on the Farm

Farmers may not realize that mercury is found in agricultural equipment. This toxic element can be found in thermometers, milk line vacuum gauges (manometers), fluorescent lighting, and as switches for refrigeration units and automatic fans.

Mercury is an element that damages the nervous system (brain and spinal cord), particularly the developing nervous system of a fetus. It is also toxic to both the kidneys and liver. Farmers can help keep mercury out of the environment and decrease their own exposure to it by recognizing the dangers of mercury and the equipment that may contain it. Replace mercury containing devices with non-mercury equipment as needed and properly recycle old mercury added devices with a Recycler.

Thermometers are used in a number of farm applications. They are used to monitor temperature in milk rooms, green houses, refrigeration units and maple sugaring evaporators. Mercury thermometers are traditionally used in these applications because of their accuracy yet non-mercury alternatives are available and perform just as well.

One should be most concerned with mercury thermometers breaking and spilling their contents. In the event a thermometer breaks, animals, people and animal feed could be contaminated. Equipment and produce would also be contaminated, requiring remediation and disposal.

NHDES has limited funds for maple producers to recycle and replace their mercury containing thermometers. Please contact the NH Pollution Prevention Program for more information about this project.

Manometers are a u-shaped device used to monitor air pressure in automatic milk lines. Proper pressure can aid in maintaining a healthy herd, while improper pressure can lead to mastitis and low milk production.

These devices contain nearly a pound of mercury. The concerns regarding mercury manometers are breakage as well as exposure due to regular usage. Manometers are open to the atmosphere to better monitor pressure and mercury can vaporize at room temperature. This causes mercury vapor exposure to farmers and animals near the unit.

Dairy experts believe that mercury manometers have probably been replaced with digital devices in New Hampshire. However, the fate of the old mercury-added devices is not known. NHDES has limited funds available for dairy farmers for recycling their mercury added manometers. Please contact the NH Pollution Prevention Program for more information about this project.

Fluorescent light bulbs come in a variety of shapes and sizes, and shapes include circle bulbs, u-tubes and straight tubes. These bulbs contain mercury and need to be handled with care to avoid breakage.

Although fluorescent bulbs contain mercury, they use considerably less electricity than traditional incandescent lighting. This efficiency helps to reduce mercury emissions at power plants, making them an environmentally good lighting choice.

Spent fluorescent bulbs should be carefully stored to prevent breakage while waiting to recycle. Contact a Vendor or take spent bulbs to a household hazardous waste collection event or to a participating True Value Hardware store for proper recycling.

Mercury switches are used to turn on lights and regulate fans, and as a safety switches for pilot lights. They are used in appliances, doors, fans, and water heaters. When replacing these devices, be sure to handle them with care to reduce the possibility of spills. When purchasing new equipment, request that non-mercury switches be used or look for non-mercury products if replacing them yourself.

For more information about this program and mercury, please contact the NHPPP at (603) 271-0878 or

NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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