Pesticides, Human Health and the Environment

An attractive landscape can be created and maintained in the Pacific Northwest without using hazardous pesticides. Effective non-chemical methods and less-hazardous products can be used inside and outside homes, schools and businesses. Increasing demand for safer products will encourage manufacturers to make products that are safer and more environmentally sound.

While many common garden products take care of short term problems, they often come with long-term costs to human health and the environment.

Hazards of pesticides

Lawn, garden, structural and indoor pesticides include some of the most hazardous chemicals commonly used. Products that kill insects, weeds, bacteria and fungi may also be toxic to children, pets, birds, fish, and beneficial insects such as bees and lady bugs.

Common insect and weed killers regularly show up in water quality tests of local streams, lakes, and Puget Sound. Rains and watering wash pesticides off of yards and carry them to streams, sometimes in amounts that can harm salmon or the aquatic animals that are their food.

Pesticides used on home landscapes or at the workplace can be carried inside on shoes and work clothes and mix with house dust. Young children, who crawl on the ground and put objects in their mouths, can then ingest the chemicals. Pesticides used on crops and landscapes are found in our bodies too.

Exposure to pesticides

People are exposed to pesticides by using them and by working or playing where pesticides are used. Exposure occurs through:

Read and follow label information to reduce the risk of pesticide exposure. Eliminate risk by not using pesticides at all.

Pesticides and children

¹In 2007, poison centers in the United States responded to 90,261 incidents related to pesticides - about half involved children under the age of six. For more information visit the American Association of Poison Control Centers. In particular:

Children are especially sensitive to pesticides, and due to their size and habits, children have the greatest pesticide exposure. Per pound of body weight, pesticides have a greater effect on children’s growing bodies and developing nervous and hormonal systems and organs.

Families with small children should make efforts to avoid using pesticides and to ensure that children don’t have access to landscapes treated with pesticides. Children playing on pesticide-treated yards can track pesticides indoors or put dirt and toys in their mouths. Pesticides tracked into the home can remain in household dust and be ingested by toddlers playing on the floor and putting fingers and other objects in their mouths.

A recent University of Washington study of Seattle-area toddlers found that nearly all of the children tested had remnants of toxic insecticides in their bodies. They had higher levels if their parents used pesticides on the landscape.

Danger to pets

Many pesticide products are toxic to dogs, cats and other pets. Slug bait containing metaldehyde poses a special risk because dogs are attracted to it and may eat enough to be seriously injured or even die. Pets access to treated landscapes may pick up pesticide residues on their paws and fur, licking it or tracking it into the house.

Cancer hazards

A number of pesticide products contain ingredients that have been listed as potential carcinogens (cancer-causing chemicals) by at least one government agency. While the testing is done on laboratory animals, and at high doses, the listing agencies carefully consider the relevance for humans. Exposure to even small doses of a carcinogen may cause cancer in a few individuals.

Some studies have found increased risk of cancer in members of households where pesticides were used regularly. Children exposed to carcinogens have more time to develop cancer than adults. Although the studies do not conclusively prove a causal relationship between the pesticides and cancer, and while some results are contradictory, the results of the studies are worrisome and provide another reason to minimize the regular use of household pesticides.

Water pollution

Many insecticides and herbicides are toxic to fish and other aquatic organisms and can reduce water quality. Aquatic organisms come into contact with pesticides and fertilizers through runoff from yards and other landscapes into streams. Monitoring studies of Puget Sound regularly find common pesticides and fertilizer nutrients in local waterways. Studies done in California urban areas have found toxic levels of insecticides in stream sediment. As the region’s population grows, pesticide levels will likely increase unless safer and less toxic alternatives are more widely used.

Toxicity to birds and bees

Most insecticides are toxic to bees and other beneficial insects and pollinators, and some insecticides are toxic to birds. Insecticides can kill bees directly or when they land on treated plants. Foraging bees can carry pesticides back to their hives, threatening the entire colony.

Many ‘beneficial’ insects help control insect pests. Since pesticides are as likely to kill the beneficial insects and pollinators as the pests, there is a potential increase in pest populations after spraying. Since beneficial insects often take longer to rebuild their populations than pest insects, spraying can create a pest population explosion.

Chemical persistence

The longer a pesticide remains in the environment, the more likely it is to do damage. Older products, like DDT, are still in the environment and human bodies almost 40 years years after their last uses were banned. Most modern pesticides have shorter lifetimes.

But even newer pesticides are not gone after a day or two, and most aren’t benign as soon as they are dry. The half-life (the time for half the product to break down in soil) of pesticides ranges from days to weeks; the half-life of some pesticides is a year or more. Some residues may remain even after many half-lives have passed, and sometimes the breakdown products are also persistent or toxic.

Hormone disruption

Many synthetic, and some naturally-occurring, chemicals can interfere with animal and human hormone systems, potentially affecting reproduction and development. These chemicals include a number of pesticides. The extent to which the observed human and wildlife health problems are caused by hormone-disrupting chemicals is not yet known.

In 1996 the federal government required that future pesticides be routinely tested for hormone disruption potential. As of early 2010, testing had not begun. See www.epa.gov/endo/

Inert ingredients

Pesticides contain both active and so-called ‘inert’ ingredients. Inert ingredients are identified on newer product labels as ‘other’ ingredients and often comprise more than 90 percent of the product. Active ingredients kill pests. Inert ingredients include solvents, detergents, and/or other chemicals that make the product work more effectively. Water is often an inert ingredient, but inert ingredients also include hazardous chemicals—sometimes more hazardous than the listed active ingredients.

On September 30, 2009, the Environmental Protection Agency announced a plan to disclose all inert ingredients in pesticides, including potentially hazardous ingredients. This increased transparency will assist consumers and pesticides-users in making informed decisions and will better protect public health and the environment. For information, see www.epa.gov/opprd001/inerts/index.htm.

1. Bronstein, Alvin C., Spyker, Daniel A., Cantilena JR, Louis R., Green, Jody L., Rumack, Barry H. and Heard, Stuart E.(2008)'2007 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 25th Annual Report',Clinical Toxicology,46:10,927 — 1057