Herbicides are organic or inorganic compounds used to eliminate unwanted plants. An ongoing challenge in the chemistry world is producing herbicides that are as selective as possible, because herbicides are often toxic not only to the weeds and other ants serving as their intended targets, but to other plants, animals and people as well. Some health risks of herbicides to humans are well-established in the literature, while others remain controversial.
Skin Rashes
A number of herbicides have been associated with irritation of the skin: rashes, itching and general irritation. Sometimes symptoms may not manifest themselves until a considerable amount of time has passed since the exposure to the offending substance, especially when the contact was not directly with the herbicide but instead was with a sprayed plant---the more common situation. A 2004 article "Toxicology Review" implicated glyphosate, the active ingredient in the popular weed killer Roundup, in causing rashes along with a variety of other health problems.
Cancer
According to studies published in 2008 in the "International Journal of Cancer" and the "American Journal of Industrial Medicine," exposure to certain herbicides, particularly those in the phenoxy class, results in an increased risk of certain cancers, notably non-Hodgkins lymphoma, or NHL, and soft-tissue sarcomas. As expected, farmers and gardeners are among those found to be at greater risk of NHL, but technical salesmen, manufacturers' agents and construction workers are at significantly greater risk as well. A Dec. 16, 1992 article in the "Journal of the National Cancer Institute" implicated phenoxy herbicides as causative or contributory agents in cancers of the colon, nose, prostate, pancreas, breast, lung and ovary, linked them to leukemia and multiple myeloma as well.
Parkinson's Disease
A 2004 Reuters article reported two new studies---one at the University of California at Los Angeles and the other at the Parkinson Institute---linking the weed-killer Paraquat to the neurodegenerative condition Parkinson's disease, which affects over a million U.S. residents and is marked by a progressive tremor that ultimately results in paralysis and death. Paraquat exposure results in the build-up of the protein alpha-synuclein in the brain---the same protein that destroys brain cells in patients with Parkinson's not linked to herbicide exposure.
Various Health Problems
Herbicides can cause a number of symptoms sufficiently common to make establishing poisoning as the cause of these symptoms elusive. According to the Partnerships for Environmental Education and Rural Health, these include headaches, nausea, diarrhea, excessive sweating or salivation, vomiting, cardiac effects, erratic behavior, labored breathing, kidney failure, convulsions and more. Herbicides causing these symptoms are most commonly absorbed through ingestion, through the skin, or by inhalation.
References
- Toxicology Review: Glyphosate Poisoning
- Northwest Coalition for Alternatives to Pesticides: Non-Hodgkin Lymphoma Linked to Herbicides in Two New Studies
- Journal of the National Cancer Institute: Herbicides and Cancer
- Reuters: Studies Line Up on Parkinson's and Pesticides Link
- Partnerships for Environmental Education and Rural Health: Pesticides and Herbicides
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