COMMON HOUSEHOLD AND LAWN PRODUCTS:INSECTICIDES AND WATER SOFTENERS

INSECTICIDES

Insecticides are used by farmers and homeowners to reduce the effect of various insects on crops, flowers, lawns, and ornamental plants. There are virtually hundreds of insecticides, many of which were developed as a consequence of early research on nerve gas weapons and which work to eliminate insects in a variety of ways. The way in which a particular pesti- cide kills an insect is called the mode of action and is a convenient way to classify the numerous available pesticides. Most traditional insecticides work on the nervous system. These chemicals are typically absorbed through the insect’s skin and affect the nerve impulses of the insect, causing paralysis and brain death. Some pesticides act to slow the pro- duction of energy needed for the insect to survive and are typically used in fumigation; the insects die after a period of lethargy. Insects have an external skeleton called an exoskeleton, of which the protein chitin is a major component. Chemicals that inhibit the synthesis of this protein kill pests because they cannot shed their exoskeleton and grow a new one. These are very specific for certain pests and have been used with great success against fleas and termites. Unfortunately, pesticides affect humans just as much as the insects they are intended to kill. The body weight of humans is much higher than that of insects, so a much smaller dose is required to kill an insect than to kill a human. However, pesticides and chronic exposure can lead to very severe health problems. Many of these chemicals can be absorbed through the skin and are acutely toxic if inhaled. As such, appropriate precautions should be taken when using insecticides, such as wearing protective garments and always following the manufacturer’s instructions.

WA TER SOFTENERS

Most people are familiar with discoloration or stains that are a result of problem water in the home. Red and brown stains caused by iron, blue and green stains caused by copper, and white scales caused by magne- sium and calcium are found in most homes with problem water. The process of softening water removes the minerals calcium and magnesium that are typically found in potable water. The removal of these elements is essential not only to make the water taste better but to prevent prob- lems associated with the deposits of these minerals in the water pipes. If these minerals are allowed to build up in pipes, they reduce water flow and pipes can eventually become completely clogged. One solution is to distill the water or to use water filters to remove the minerals. This approach is impractical because of the high cost associated with filtering or distill- ing all of the water used in the household. A more cost-effective approach, water softening, removes magnesium and calcium by a replacement pro- cess. A water softener contains a bed of small plastic beads or a zeolite matrix, which is saturated with sodium chloride. As water flows through the softener, the calcium and magnesium are replaced by sodium ions. This process is called ion filtration. The undesirable calcium and magne- sium remain in the softener and sodium ions are introduced to the water supply. Sodium does not cause precipitation problems, and the effects of hard water are eliminated.