In humans, arsenic causes arsenicosis which causes skin problems including skin cancer, bladder, kidney and lung cancer, disease to the blood vessels of the legs and feet which can lead to gangrene, and is suspected to contribute to diabetes, high blood pressure, and reproductive disorders. [Source WHO] The WHO's Guideline Value for arsenic in drinking water is 0.01 mg /litre.
The problem of arsenic in drinking water can be tackled by harvesting rainwater - a strategy routinely advocated in permaculture.
Arsenic also affects agriculture in two ways: arsenic is drawn into plants contaminating the plant; and arsenic is drawn up instead of phosphorus, which is a major limiting factor in plant growth. The result is a plant that has a degree of toxicity and is stunted due to lack of phosphorus. When groundwater irrigation is utilised in areas with arsenic contamination, these problems appear.
The use of swales, or water-harvesting ditches on contour, is the most cost effective type of earthworks for capturing water. It also reduces or eliminates the need for groundwater irrigation.
Additionally, endomycorrhyzal fungi can be employed to help alleviate the arsenic problem. Plants with the endomycorrhyzal fungi Glomus mosseae have been show to reduce plant uptake of arsenic and increase the uptake of phosphorus as reseach by the University of Aberdeen recently shows:
Arsenic (As) contamination of irrigation water represents a major constraint to Bangladesh agriculture. While arbuscular mycorrhizal (AM) fungi have their most significant effect on P uptake, they have also been shown to alleviate metal toxicity to the host plant. This study examined the effects of As and inoculation with an AM fungus, Glomus mosseae, on lentil (Lens culinaris L. cv. Titore). Plants were grown with and without AM inoculum for 9 weeks in a sand and terra green mixture 50:50 v/v and watered with five levels of As (0, 1, 2, 5, 10 mg As L-1 arsenate). Inoculum of Rhizobium leguminosarum b.v. Viceae strain 3841 was applied to all plants. Plants were fed with modified Hoagland solution (1/10 N of a full-strength solution and without P). Plant height, leaf number, pod number, plant biomass and shoot and root P concentration/offtake increased significantly due to mycorrhizal infection. Plant height, leaf/ pod number, plant biomass, root length, shoot P concentration/offtake, root P offtake and mycorrhizal infection decreased significantly with increasing As concentration. However, mycorrhizal inoculation reduced As concentration in roots and shoots. This study shows that growing lentil with compatible AM inoculum can minimise As toxicity and increase growth and P uptake.Also see More Evidence of Mycorrhizal Fungi as Arsenic Beater.