Pesticides

The word "pesticide" includes all chemicals that are used to kill or control pests. They include herbicides (kills weeds), insecticides (kills insects), fungicides (kills fungi), nematocides (kills nematodes), and rodenticides (kills small mammals).

Pesticides are most heavily used in agriculture but they are also heavily used in household as well as silvicultural applications. Other pesticides are used to control insect pests for the general population, such as the use of DDT in tropical countries to control malaria. (While DDT is banned in North America it is still in widespread use in many developing countries.)

Of the pesticides that are used far less than 1% actually reaches a target organism; the rest ends up contaminating the air, soil, water, plants and animals. Furthermore while farmers use three times the amount of agricultural chemicals today than they did forty years ago we are still losing about 1/3 of our crops to pests; which is about the same as forty years ago. (Brady, 1996).

Concerns

Pesticides are of concern for human health because many are lipid soluble and as such they accumulate in our fatty tissues in a process called bioconcentration. Biomagnification is what happens when organisms eating contaminated organisms concentrate the pesticides and then in turn are eaten by other organisms. As a result those on the top of the food chain (all meat-eating humans) are most at risk because the concentration is magnified at each step of the food chain.

Furthermore because pesticides are designed to kill organisms due to their neurological or reproductive toxicity they also have many similar deleterious effects in humans, and many show adverse effects on the immune system at very low doses.

Pesticides have many ecological effects of concern as well. Ecological effects are often considered to be an early warning indicator of potential human health impacts.

In the environment pesticides can kill organisms, cause cancer, tumors and lesions in fish and wildlife, suppress the immune system, cause reproductive failure, damage DNA, disrupt the endocrine (hormonal) system, and cause physiological birth defects such as deformed beaks on birds or malformed reproductive organs such as observed in alligators exposed to DDT. Pesticides cause a dramatic decline in biodiversity in areas where used and cause a shift in the species balance in the plant communities, with cascading effects throughout the food chain. Some pesticides such as the carbamates have been shown to be highly toxic to earthworms. Many insecticides and fungicides have been shown to interfere with nitrogen fixing bacteria in the soil, which often contribute significantly to plant growth where nitrogen is limiting (nitrogen is usually limiting).

Types of Pesticides

Many groups of pesticides are a concern to human and environmental health. Insecticides fall into 3 general groups: the chlorinated hydrocarbons like DDT have been banned or severely restricted in many developed countries due to their persistence and toxicity in the environment, however they are still in widespread use in many developing countries. Chlorinated hydrocarbon compounds tend to be highly toxic as they also accumulate in fatty tissues of organisms and they remain un-degraded in the soil for 3-20 years, or even longer. See Dioxins for a highly lethal example of a chlorinated hydrocarbon. Many chlorinated hydrocarbon compounds are causing concerns for Arctic animals, far from any source of pollution. The organophosphates are more biodegradable and hence less persistent than the chlorinated hydrocarbons but they are extremely toxic to humans and present a significant health risk to children. See Organophosphates below. The carbamates are considered the least dangerous because of their biodegradability and their relatively low mammalian toxicity. However they are highly toxic to honeybees, earthworms and beneficial insects (Brady, 1996). See Carbamates below.

Herbicides are the most widely used pesticide and cover a wide range of chemicals with as wide range of properties and effects. Many are toxic to fish, aquatic organisms, and have been implicated in various ill effects in humans. See Herbicides, below, for more on types of commonly used herbicides.

Different components of pesticides may pose separate risks and so in evaluating safety all factors should be considered. These include the active ingredients, contaminants (such as dioxins in 2-4 D), additive or "inert" ingredients (which at teams can be very toxic), and the breakdown products in the environment. (For example when DDT breaks down in the environment it becomes the more lethal DDE).

Pesticides and Children

Pesticides are of particular concern for children because of the hormone - like nature of many synthetic pesticides. Growth and development is hormone driven, putting children at high risk. Children also eat more and drink more per kg of body weight as compared to an adult, so they absorb larger quantities of pollutants. Also because they are smaller and their body's are not yet mature they are less able to metabolize and eliminate residual toxic substances.

Children can be exposed multiple times in multiple places, even if we do our best to protect them from it. Some areas of concern, aside from proximity to agricultural use and exposure in foods children are also exposed from indoor pest control applications, household use of insecticides, flea powders and collars, lawn and garden insecticides and herbicides. There is also the concern over improper storage of old, and often discontinued pesticides in people's garages, as well as when they are disposed of into the garbage. Young children are particularly at risk due to soil and dust tracked in on shoes that is contaminated with pesticide residues from the lawn and garden. Once indoors the pesticides are highly resistant to breakdown and they can be found on children's toys which are put in the mouths of young children. Children are also exposed at school and on playgrounds where herbicides are commonly used, and also when they play on playgrounds built with pressure treated lumber. Pressure treated lumber is treated with CCA a chromium and arsenic pesticide; most arsenic pesticides were banned years ago but we still use them extensively in wood preservation. Finally children are exposed to pesticides in the air, drinking and swimming water; danger increases with proximity to the site of application.

About Persistant Organic Pollutants

and Pregnant Women

Many pesticides are classified as Persistant Organic Pollutants, particularly organophosphates (see below) and those contaminated with dioxins. Persistent organic pollutants (POPs) include chlordane, dieldrin, DDT, heptachlor, dioxins, toxaphene and more. These substances are of particular concern because of their effects on the endocrine system of the developing fetus which is important for the healthy development and functioning of many critical organ systems, particularly those involved in sexual development, reproduction, and behavior. Scientists feel there is a link between fetal and neonatal exposure to POPs and the increase in a number of diseases including testicular cancer, endometriosis, and breast cancer, as well as reduced IQ, immune suppression, nervous system and hormonal disorders, and birth defects. The dramatic reduction in sperm count in industrialized countries (50% in the last 50 years!) has also been linked to POP's, particularly dioxins.

For a pregnant woman, the proper functioning of her and her fetus' hormone system is critical for the baby's proper development. If not functioning properly this can alter fetal development resulting in permanent repercussions for the child. Sometimes however these problems may not appear until well into puberty or even later in a child's life.

Pregnant women commonly alter their diets during pregnancy and nursing to accommodate the nutritional needs of the fetus and infant; in ways that often can increase their baby's exposure to POP's. However why should we sacrifice nutrition or feel guilt for the poisons on our food? These substances should be eliminated so that women can know that they are doing the best for their unborn child by eating nutritious food. But if its not organic we could be harming our child in irreparable ways.

Furthermore when we breastfeed we pass off our own body burden into our babies. Essentially all human breast milk is contaminated with POP's including PCB's (polychlorinated byphenols), DDE (the more toxic break-down product of DDT) and dioxins. When a mother breastfeeds we pass off some of this body burden as well as the other POP's we are still ingesting into our babies. The benefit for mothers is that their body burdens decrease dramatically after breastfeeding for 6 months or more. The problem is of course that it is unloaded into the body of our newborn babies at critical stages in his/her development. Through breast milk, infants can ingest a much higher dose, pound for pound, than an adult gets on an average day. For example breastfed infants can ingest thousands of times more dioxins than the average adult. (See Dioxins for more on this). It just doesn't seem fair at all, why should mothers feel fear or guilt over doing what is naturally best for their babies eating nutritious food and breastfeeding?

Canada ratified the 1998 protocol on the elimination of POP's. This protocol lists 16 POP's with 11 of these being pesticides. However other countries will continue to use them and we import a good percentage of our fruits and vegetables from those countries, particularly in winter. So even though we may not be using them we are still ingesting them and accumulating them due to their persistent nature. We need to ban all POP's immediately and globally; this is the only answer.

Degradation of Pesticides

With most of the pesticides ending up in the soil, air and water then where does it go from there? Well pesticides are degraded by a number of chemical and. They also degrade due to microbiological processes and metabolic process when organisms ingest and degrade the substances

When the pesticides land on the ground they may then vaporize into the atmosphere, they may be absorbed onto the soil surfaces, they may be leached from the soil by water and carried into the groundwater, or washed off from the surface and into rivers and lakes. They can also undergo chemical reactions within the soil or on the surface, be degraded by photochemical (reactions involving sunlight) reactions on the surface, or metabolized by organisms and broken down. Energy used to degrade pesticides is then not available to the organism to provide other necessary functions. They may also be taken up by organisms and concentrated and passed up the food chain. This is particularly true for the higher plants and for those pesticides (such as systemic insecticides and most herbicides on the market) that must be taken up by the organism to perform its function. The pesticides can then remain in the plants or be degraded into either less, or more, harmful breakdown products. (Note that DDE, the breakdown product of DDT, is far more lethal). The ultimate fate of the pesticide depends on the nature of it; how persistent and resistant it is, whether it is water or lipid soluble

Re-Evaluation

Canada and the US are currently engaged in a re-evaluation of pesticides, some of which were approved and have not been re-evaluated since before 1960. Health Canada is suggesting to include an additional safety factor of 10 to protect children who are more at risk from the toxic effects of pesticides. They have also recommended further research devoted specifically to child health and pesticide toxicity. The complete re-evaluation is to be completed by 2006. In the meantime while awaiting for these re-evaluations to be complete there are many alternatives and some other solutions we could be looking at.

Pesticide Solutions & Alternatives

Reduce Pesticide Use and implement Integrated Pesticide Management and improved application procedures (or better yet Go Organic Check out Lyrae's Herb & Garden Pages: Organic gardening for information on how you can become an organic gardener at your home).

STOP SUBSIDIZING CHEMICAL FARMING METHODS SO HEAVILY!! We need to consider taxing pesticide use or penalizing it in some way by reducing subsidies so that farmers are forced to reduce their use. Even with all the "advances" in pesticides we are still losing a significant portion of our crops to insect pests, so the "gains" are hardly worth the risks.

We should also consider subsidizing organic farmers since they are less of o burden on us financially through reduced costs in health care.

We are currently re-evaluating all pesticides approved years ago before the more stringent rules, but we must re-evaluate both active and "inert" ingredients.

Limit or eliminate aerial spraying which is wasteful and dangerous.

Work on a way to enforce global bans on pesticides many harmful pesticides are cheap and effective and in widespread use in developing countries. But pesticides travel well through organisms, air and water. Pesticide contamination is recognized as a problem as far away as the Arctic where pesticides are not even used.

Stop the use of arsenic pesticides in pressure treated lumber (CCA lumber).

Pass regulations eliminating the use of pesticides next to waterways including lakes, creeks, rivers and oceans.

9. Stop the cosmetic use of pesticides!!! I don't know about you but I am a whole lot happier to see dandelions on my lawn than to risk the possibility of killing or harming my child.

And more on different types of pesticides of particular concern...

Organophosphates

All organophosphate pesticides function by inhibiting the acetylcholinesterase Enzyme, disrupting the transmission of nerve impulses.

Methyl Parathion

Methyl Parathion is an organophosphate pesticide that is dangerously over used in North America. It was approved for use many years ago but never would have been approved under today's standards. It is a potent neurotoxic pesticide that kills bugs by disrupting vital transmitters in their nervous systems. The pesticide works the same way in people. Methyl Parathion has the lowest "maximum safe daily exposure level" of any pesticide registered by the EPA. Like most organophosphates methyl parathion has been shown in rats to be more toxic to fetuses and infants than to mature rats.

An estimated 320,000 children between the ages of one and five years old eat an unsafe dose of methyl parathion in their food every day. And more than 55,000 of those children exceed the safe dose by a factor of ten or more each day, with 2,400 of those children exceeding the safe daily dose by more than 100-fold. Some apples are so contaminated that 2 bites can be unsafe for children under six, add to this organophosphate exposure from other food, air and water. And these estimates are based on food that has already been washed, cook and prepared for consumption, which often removes significant amounts of pesticides. To look at this another way, , if there's any methyl parathion in a child's food, there is about a 50-50 chance that the child is getting an unsafe dose.

Foods most likely to put children at risk: Grapes appear to be unique among high-risk foods. Based on studies by the Environmental Working Group seventy (70) percent of the children who got an unsafe dose of methyl parathion eating grapes, exceeded the safe dose by a factor of ten or more. This is believed in part due to the fact that children typically eat larger numbers of grapes. Peaches, apples and pears are also a safety concern, with 11 to 36 percent of children exposed to an unsafe dose exceeding the exposure level by a factor of ten or more.

From Overexposed: Organophosphate Insecticides in Children's Food; the Environmental Working Group, 1998:

Choropyrifos

Chlorpyrifos was banned in the summer of 2000 by the US EPA. (at the time of this research Canada has yet to take similar action). It was (is) one of the most widely used pesticides in household applications. Chlorpyrifos when ingested by animals is converted to chloropyrifos-oxon which is a substance that is about 3000X more toxic than chloropyrifos itself. Chloropyrifos is more persistent than most organophosphates, possibily because it is stored in fatty tissues and released over time. The substance has been linked to behavioral changes, reduced IQ, memory problems, multiple chemical sensitivities, immune abnormalities and motor skills impairment. Chloropyrifos is particularly toxic to children, which is a significant factor in the recent ban in the USA. Dursban is a common trade name and this product is still found on store shelves (because it has only been discontinued and not recalled) and stored in household cupboards, so even with the ban the threat is still far from over. Bug-B-Gon may contain chlorpyrifos and this is still found on store shelves.

Diazanon

Diazanon is marketed mostly for household use but is also used in agricultural applications. Bug-B-Gon is a popular household pesticide that often contains diazanon. It is a frequently detected air pollutant and one of the most commonly detected insecticides in urban and agricultural watersheds. Diazanon, like all organophosphates, is a neurotoxin. It causes headaches, dizziness, nausea, blurred vision, impaired memory and motor skills. In rats when the fetus was via its mother the offspring show birth defects, motor skills impairment and delayed sexual development. Ecological effects include bird and fish mortality, interference with nitrogen fixing soil organisms, and reductions in the numbers of eggs laid by birds. Diazanon has also shown to be synergistic in that it is even more toxic when combined with other toxins. (From pesticide.org)

Malathion

Malathion is used agriculturally and for household use. It has been implicated as being carcinogenic, it is mutagenic and often contains toxic impurities. Furthermore there is a higher incidence of occupational illness in workers exposed, per pound sold, than the average pesticide. Yet it has been called an organophosphate with "low acute mammalian toxicity". In the environment malathion is often far more toxic to the beneficial insects than the target pests. It has shown to be toxic to birds, honeybees and amphibians and it inhibits nitrification in soil organisms.

Carbamates

Carbamates act in a similar manner to organophosphates in that they inhibit the enzyme acetylcholinesterase, the enzyme essential for proper nerve functioning in insects and mammals. Carbamates are less toxic than organophosphates in that their ill side effects are more reversible. However carbamates still present several concerns for human and ecological health.

Aldicarb

Aldicarb is widely used on cotton, soy, beans, sweet potatoes and sugarbeets. Aldicarb is a systemic pesticide that is applied below the soil surface and may be found in the soil 1 year after application. Aldicarb is toxic to earthworms and beneficial insects, it is a reproductive toxin linked to stillbirths, it has negative impacts on fish and aquatic life, and has been shown to impair immune e system functioning, even at very low doses. Furthermore aldicarb is a highly acute toxin, very small doses can be lethal. No carcinogeniteity has been detected but this could be due to its acute toxicity which would make it difficult to detect cancers. (from pesticide.org)

Carbaryl

Carbaryl has a wide number of uses with citrus and grapes being two prominent ones. It is sold for agricultural and household applications. Carbaryl has been shown to interfere with components of the immune system; rats exposed to carbaryl were twice as likely to die of bacterial infections than those not exposed. It causes a range of behavioral and neurological side effects, and is associated with non-Hodgkin's lymphoma and childhood brain cancer. Its reproductive effects include reduced quantity and quality of sperm in males, and decreased fertility, higher fetal mortality and lower birthweights, growth and survival of infants in females.

Herbicides

Glyphosphate (Round-Up)

Round up is Monsanto's biggest cash cow; it is a widely marketed and heavily used broad spectrum herbicide. Monsanto is a huge chemical giant with a history of fraud, among other things. They were until very recently also involved in the biotech industry when they sold off their biotech division to Pharmacia & Upjohn due to bad publicity. Monsanto genetically engineered soy, corn and others to be "Round-Up Ready" so that they could withstand even heavier dousings of glyphosphate as the pests are becoming resistant.

Glyphosphate is an acute toxin that causes skin and eye irritation, nausea, headaches, numbness and heart palpitations. It also inflames the stomach lining, causes genetic damage, reduces sperm count in rats, and shows an increase in miscarriages, premature births and non-Hodgkins Lymphoma in farmers.

In the environment glyphosphate reduces biodiversity and reduces the numbers of beneficial insects, birds and small mammals by destroying their food sources. It has also been shown to increase a plant's susceptibility to diseases and it inhibits the growth of nitrogen fixing bacteria in the soil.

2, 4-D ("Weed and Feed" etc)

2,4-D is the most commonly used herbicide in the world, with 50 million pounds of it being used each year in the US alone.

2,4-D is a selective toxin used against broadleaf weeds and is widely used on lawns to get rid of dandelions. It works by mimicking hormones that control plant growth and development resulting in abnormal growth and death. In animals it disrupts energy production (interferes with adenosine triphopsphate (ATP) synthesis), and interferes with protein synthesis and lipid metabolism. In rats exposed while in the womb offspring showed a reduced brain size and genetic mutations. In humans 2,4-D causes drowsiness, vomiting, dizziness, kidney & liver injury, muscle twitching, eye irritations and skin lesions.

Pesticide Links

EPA Pesticides Site

http://www.epa.gov/pesticides/

The NorthWest Coalition for Alternatives to Pesticides

http://www.pesticide.org/

The pesticides Action network of North America searchable database

http://www.panna.org/index.html

Canadians Against Pesticicdes Website

http://www.caps.20m.com/

A searchable website on pesticides:

http://ace.ace.orst.edu/info/extoxnet/