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Pesticides, human health and the environment
- Lawn, garden, and indoor pesticides include some of the most hazardous chemicals commonly used at home. Products that kill insects, weeds, bacteria and fungi may also be toxic or hazardous to children, pets, birds, fish, other wildlife, and also to beneficial insects like bees and lady bugs.
- Pesticides used outside at home 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 also found in our bodies.
- Common insecticides and weed killers regularly show up in water quality tests of local streams, lakes, and Puget Sound and the Columbia River. Rain and irrigation wash pesticides off of yards and carry them to streams, sometimes in amounts that can harm salmon or the aquatic organisms that are their food.
Exposure to pesticides
People are exposed to pesticides by using them and by working or playing where pesticides are used. Exposure comes through:
- direct skin contact,
- inhaling dust or mist while using pesticides,
- contact with treated plants or soil,
- tracking pesticides into the home on shoes, work clothes, and/or pet,
- and eating food that contains pesticide residues.
Read and follow label information to reduce the risk of pesticide exposure. Not using pesticides reduces your risk of exposure even more.
Pesticides and children
Children are vulnerable to accidental exposure to pesticides.
- In 2009, United States poison centers had 91,588 incidents related to acute exposures to pesticides - about 45% involved children under the age of six. For information visit the American Association of Poison Control Centers. In particular:
- 14,875 people were treated at a health care facility for pesticide exposures.
- 2152 incidents resulted in moderate or major health outcomes.
- There were 21 deaths.
If you keep pesticides and fertilizers at home, store them safely and securely. They can contain ingredients that are very dangerous if ingested.
Chronic exposures. Children are vulnerable to repeated, very small, unintended exposure to pesticides. They are much more sensitive to pesticides and chemical exposures than adults.
- 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 play on 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 get into toddlers mouths when they play on the floor and put fingers and other objects in their mouths.
A 1998 University of Washington study of Seattle-area toddlers found that nearly all of the children tested had metabolites of toxic insecticides in their bodies. They had higher levels if their parents used pesticides on the landscape.
Pesticides and pregnancy
Environmental chemicals, including pesticides, are known to collect in the bodies of humans. See details in the Fourth National Report on Human Exposure to Environmental Chemicals 2009. We are not sure how this body burden (chemicals stored in our bodies) is affecting our health or the health of our developing children.
Studies looking at human health effects of pesticide exposure suggest a number of potential concerns.
- Exposure before pregnancy may increase the time it takes for a woman to conceive.
- Exposure during pregnancy may affect the size of the baby and may increase the risk of birth defects and fetal death.
- Some studies also suggest adverse reproductive outcomes are possible with both maternal and paternal exposures.
See Systematic Review of Pesticide Human Health Effects, 2004.
You can reduce the risk of cancer and other health effects from pesticide exposure by eliminating exposure where possible, in your home or product purchasing. Completely eliminating the risk of pesticide exposure is difficult at the current time, as pesticides are used in public places, along road and water ways and on agricultural crops.
There may be a relationship between pesticides and cancer:
- "Leukemia rates are consistently elevated among children who grow up on farms, among children whose parents used pesticides in the home or garden, and among children of pesticide applicators." Page 44 2008–2009 Annual Report | President’s Cancer Panel
- "Occupational exposure to these chemicals (pesticides) has been linked to brain/central nervous system (CNS), breast, colon, lung, ovarian (female spouses), pancreatic, kidney, testicular, and stomach cancers, as well as Hodgkin and non-Hodgkin lymphoma, multiple myeloma, and soft tissue sarcoma." Page 45 2008–2009 Annual Report | President'’s Cancer Panel
- "…there are many studies showing positive associations between solid tumors and pesticide exposure." Page 16 Systematic Review of Pesticide Human Health Effects. Solid tumors refer to cancers of the lung, breast, pancreas, brain, prostate, stomach, ovaries, and kidneys.
Danger to pets
Many pesticide products are toxic to dogs, cats and other pets.
- Pets with access to treated landscapes may pick up pesticide residues on their paws and fur, licking it or tracking it into the house.
- 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.
Many insecticides and herbicides are toxic to fish, amphibians and other aquatic organisms and can reduce water quality. As the region’s population grows, pesticide levels will likely increase unless safer and less toxic alternatives are more widely used.
- Aquatic organisms come into contact with pesticides and fertilizers through runoff from yards and other landscapes into streams.
- Monitoring studies in the Puget Sound region find common pesticides and fertilizer nutrients in local waterways.
- Studies done in California urban areas have found toxic levels of insecticides in stream sediment.
- Pesticide impact is evaluated by its intended use; if it travels to unintended places by water, soil or air it can have unintended – and unmeasured effects.
Toxicity to birds and bees
Most insecticides are toxic to beneficial insects, bees and other 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.
- Some researchers believe that pesticide use may be implicated in honey bee colony collapse disorder.
Many beneficial insects – good bugs – help control insect pests. Since pesticides can kill beneficial insects and pollinators with the pests, pest populations can increase after spraying. Beneficial insects often take longer to rebuild their populations than pest insects, so spraying can create a pest population explosion.
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 in our bodies almost 40 years after their last uses were banned.
Most modern pesticides have shorter lifetimes. However, even newer pesticides are not gone after a day or two, and many aren’t harmless just because the treated area has dried. The half-life (the time for half the product to break down in soil) of pesticides ranges from days to weeks to 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.
Garden products are designed to breakdown in outdoor conditions; if they travel into your home they may last longer.
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 human and wildlife health problems are caused by hormone-disrupting chemicals is not yet known.
In 1996 the federal government required pesticides to be routinely tested for hormone disruption potential. EPA ordered the first chemical testing for potential hormone effects in 2009; results of the studies will be available beginning in 2011.
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 hazardous chemicals-solvents, detergents, and/or other chemicals that act as carriers and can make the product work more effectively.
In 2009, the Environmental Protection Agency began planning discussions about the disclosure of all inert ingredients in pesticides, including potentially hazardous ingredients. This transparency would assist consumers in making informed decisions and help protect public health and the environment. For information on the current status of this discussion.