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Common toxic pesticides sold for home gardens PDF Print E-mail

(With reference to www.scorecard.org )

A trip to the local garden centre or hardware store reveals a significant range of toxic pesticide products sold for home and garden use. All pesticide products contain Active Ingredients (the killing agent/s) as well as other ingredients such as solvents, wetting agents and synergists to make up the formulated product.  In some instances the other ingredients, often referred to as ‘inert’ ingredients can increase the overall toxicity of the product.

Chlorpyrifos

Chlorpyrifos is one active ingredient which appears in several products, but is sold primarily for controlling ants and caterpillars in a range of situations. Chlorpyrifos is an organophosphate pesticide suspected to be an endocrine toxin, a nerve toxin and a reproductive toxin in humans, especially children.

The Pesticide Action Network (USA) Chlorpyrifos fact sheet reports that "Typical diets, particularly those of children, contain significant Chlorpyrifos residues. About 10 percent of the food items tested by the U.S. Food and Drug Administration contained Chlorpyrifos residues, and illegal residues occur on many foods.

In addition people are exposed when their homes or workplaces are treated with Chlorpyrifos. When homes are surveyed for pesticide residues, typically Chlorpyrifos is found in all residences tested.

Chlorpyrifos contaminates air, ground water, rivers, lakes, rainwater, and fogwater. Chlorpyrifos contamination has been found up to 24 kms from the site of application.

Chlorpyrifos residues have been found in soil up to eight years after termiticide treatments under a house, and in indoor air up to 6 weeks after "crack and crevice" treatment (a treatment aimed at areas favoured by household insect pests). In most studies, residues persist until the end of the study so that establishing a definite persistence time is difficult.

Children appear to be more susceptible to Chlorpyrifos poisoning than adults, and are often exposed to more residues.  The U.S. Environmental Protection Agency estimates children consume (after adjusting for their size) between 2 and 2.5 times as much Chlorpyrifos on their food as do adults. When houses are treated with Chlorpyrifos, carpets can serve as a source of Chlorpyrifos vapours when residents return. Infants, who crawl and sit on the carpet, will breathe much higher concentrations than adults".   

Chlorpyrifos is one sobering example of the importance of adopting organic pest controls at home.

The ‘natural’ trap - shoppers should beware of misleading advertising.

* “Natural pyrethrum” is used to promote the sale of this general purpose insecticide used for controlling sap sucking and chewing pests, like caterpillars. The lure is the word ‘natural’ and many gardeners will have heard that pyrethrum is derived from the flowers of pyrethrum, a type of daisy. Reading the back of the pack you’ll discover that this product mostly contains a synthetic pyrethroid-based pesticide with only a small amount of genuinely natural pyrethrum extract. Fortunately it’s possible to buy genuine, natural pyrethrum but you must check that the pack says that it’s certified organic. Even confident and organic gardeners can fall into this advertising trap.

* Piperonyl butoxide, is a compound often added as a synergist (ie something that enhances the toxicity), to insect sprays containing pyrethrins, pyrethroids and carbamates. It works by blocking or inhibiting the function of enzymes which break down the poison in the insect.  In humans it is thought to reduce the response of the immune system to assaults by other chemicals and organisms.

Other toxic chemicals that are commonly sold (and endorsed by respected gardening authorities) include:

* Myclobutanil, a synthetic conazole fungicide. Myclobutanil is recognised as an agent that causes adverse effects on the developing child. Effects can include birth defects, low birth weight, biological dysfunctions, or psychological or behavioural deficits that become manifest as the child grows. Maternal exposure to toxic chemicals during pregnancy can disrupt the development or even cause the death of the foetus.

Myclobutanil is also recognised as a reproductive toxin. Exposure to this type of chemical can cause adverse effects on the male and female reproductive systems. Reproductive toxicity may be expressed as alterations in sexual behaviour, decreases in fertility, or loss of the foetus during pregnancy. A reproductive toxicant may interfere with the sexual functioning or reproductive ability of exposed individuals from puberty throughout adulthood. Toxins that target the female reproductive system can cause a wide variety of adverse effects. Changes in sexual behaviour, onset of puberty, cyclicity, fertility, gestation time, pregnancy outcome, and lactation as well as premature menopause are among the potential manifestations of female reproductive toxicity: all can disrupt a woman’s ability to successfully reproduce.

* Mancozeb, a dithiocarbamate fungicide, for general fruit and other fungal diseases. Recognised as a carcinogen, a compound capable of inducing cancer in humans or animals after prolonged or excessive exposure.

Chemically-induced cancer generally develops many years after exposure to a toxic compound. Suspected to be an endocrine toxin and an immunotoxin. Immunotoxicity is defined as adverse effects on the functioning of the immune system that result from exposure to chemical substances. Altered immune function may lead to the increased incidence or severity of infectious diseases or cancer, since the immune system’s ability to respond adequately to invading agents is suppressed. Identifying immunotoxins is difficult because chemicals can cause a wide variety of complicated effects on immune function.

* Methiocarb is a carbamate pesticide sold for controlling slugs and snails. Suspected to be a nerve toxin, further data needed to assess long term impacts on human health.

* Metaldehyde is widely and commonly used for controlling slugs and snails. A known stomach poison affecting children and pets (dogs especially). Metaldehyde is highly toxic when inhaled and home gardeners rarely wear a respirator or dust mask when applying snail bait granules. Further research is needed to assess the long term impacts on human health because there is insufficient data concerning its use.

* Rogor or dimethoate, is a systemic organophosphate, used for controlling a wide range of sap-sucking and chewing pests. A known nerve poison, a suspected carcinogen, a blood toxin, endocrine toxin, liver, kidney and gastrointestinal toxin and a respiratory toxin in humans.

* Maldison, is a systemic organophosphate, used for controlling a wide range of sap-sucking and chewing pests in a similar way to Rogor.

* Copper oxychloride sold for controlling foliar fungi. This can be substituted by using cupric (copper) hydoxide which is acceptable for organic gardens.

* MCPA sold for controlling for broad-leaved weeds in lawns. A suspected carcinogen, gastrointestinal or liver toxin, kidney toxin and nerve toxin in humans.

* Dicamba, a synthetic hormone herbicide for controlling broad-leaved weeds in lawns. Dicamba is suspected to be a developmental toxin and reproductive toxin in humans.

* Mecoprop, a phenoxy hormone herbicide used for broad-leaved weeds in lawns. Mecoprop is suspected to be a gastrointestinal, liver and kidney toxin.

Jerry Coleby-Williams
28th February 2007

References:

* Scorecard

* The Pesticide Action Network 

* The Australian Pesticides & Veterinary Medicines Authority 

 
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