The Global Problem of Lead Arsenate Pesticide

By Chido Mpofu, Intern at the Global Lead Advice and Support Service (GLASS),
run by The LEAD Group, Sydney Australia, 13 January 2010.

Background

The use of lead arsenate insecticide was an internationally accepted practice adopted because of its effective control of insect pests and its low phytotoxicity [phyton: Gr= plant], compared to its contemporaneous alternatives (Peryea, 1998).

Lead arsenate insecticide was used in many countries ,  including  Australia, Canada, New Zealand and the USA. It was used for insect pests on apples and other fruit tree, garden crops and turf grasses, on rubber and coffee trees and for mosquito abatement in cattle dips. (Peryea, 1998).

Termination of the Use of Lead Arsenate in the USA and Australia

The use of lead arsenate was terminated in early 1950s in Massachusetts, USA, in New York and other States in the mid 1960s, and in  1984 in Washington State.  All insecticidal uses of lead arsenate in the USA were officially banned on 1 August 1988 (USEPA, 1988), with a comment that all registrations for insecticidal use had lapsed before that date.

In Australia, use of lead arsenate decreased after the introduction of DDT in 1950, and it has not been used on exported crops since 1983 (Peryea, 1998).

How exposure to lead arsenate is possible

Many of the lead arsenate-contaminated sites occur in former rural locations that are undergoing urbanization, particularly residential development. A variety of remediation strategies have been employed or proposed, including removal of contaminated topsoil by excavation,  and encapsulation by maintaining a continuous grass turf surface. Keeping lead arsenate-contaminated soils in orchard production effectively limits human exposure to lead arsenate, because the fruit doesn’t generally contain significant concentrations of lead or arsenic. In the days of early settlement of Australia, market gardens existed in what is now a town or city centre, or on the fringes. The implication of this is that people buying land or a house in one of these areas should investigate the history of the area, to see if it once had market gardens.

Exposure to lead arsenate pesticides in former orchard soils involves contact with the bare soils.

Some common activities that may increase exposure are:

• Gardening or digging in the soil,
• Children playing in contaminated soil (particularly if not washing after play),
• Eating without first washing hands and face after digging in soils, and
• Eating unwashed vegetables grown in the soils.

(Reference: Wisconsin Department of Health and Family Services)

Health Problems Caused by Lead Arsenate

The symptoms which follow oral exposure include severe gastrointestinal damage resulting in vomiting and diarrhea, and general vascular collapse leading to shock, coma and death. Muscular cramps, facial edema, and cardio-vascular reactions are also known to occur following oral exposure to arsenic (EPA, 1986)

General recommendations to Avoid Exposure (Prepared by the Wisconsin Department of Health and Family Services)

• Sampling orchard soils
• Soil sampling should be conducted when an agricultural property changes to other land use (e.g. farmland changed to a residential development or park).

For properties already redeveloped, sampling can be focused in areas where contact with the soils is expected (e.g. children’s play areas or gardens).

Limit Access to Contaminated Soils

• Cover any exposed or bare soil with grass, vegetation or other surface material (e.g. gravel or pavement).
• Bring in clean sand for sandboxes; and soil from a non-orchard area for gardens.
• When developing new residential areas in former orchards, plan landscaping so the top six inches of original soil is covered beneath cleaner soils.

Minimize Exposure

When contact with soils cannot be avoided, some basic habits will significantly reduce exposures and related health concerns:

• Wash hands and face after touching soil and before meals and snacks.
• Wash fruits and vegetables from your garden before eating. Uptake of arsenic and lead by plants is less of a concern than eating produce with soil stuck to it.
• Keep toys and pacifiers clean when used outside.
• Avoid tracking soil into the home and clean up right away if it happens.

REFERENCES

EPA US (Environmental Protection Agency, United States) Lead Arsenate EPA Pesticide Fact Sheet 12/86, , December 1986, Retrieved from Pesticide Management Education Program (PMEP), Cornell University Cooperative Extension, http://pmep.cce.cornell.edu/profiles/insect-mite/fenitrothion-methylpara/
lead-arsenate/insect-prof-leadars.html

Peryea, F. J. Tree Fruit Research and Extension Center, Washington State University, Wenatchee, Washington, USA. Retrieved from Wisconsin Department of Health Services http://dhs.wi.gov/eh/HlthHaz/pdf/LeadArPest.pdf

Proceedings, 16th World Congress of Soil Science (CD Rom), Montpellier, France. 20-26 Aug. 1998.

Schooley, T. N., Weaver, M. J., Mullins, D. E., Eick, M . (2008). The History of Lead Arsenate Use in Apple Production: Comparison of its Impact in Virginia with Other States. Journal of Pesticide Safety Education, V. 10, p. 22-53. Retrieved from http://web.ento.vt.edu/ento/showPub.jsp?pubNum=880

THUPPIL, Dr Venkatesh. National Referral Centre for Lead Poisoning in India (NRCLPI), photo of tins of lead arsenate and white lead from his presentation "EFFECT OF ENVIRONMENTAL LEAD ON THE HEALTH STATUS OF WOMEN AND CHILDREN IN DEVELOPING COUNTRIES", INCHES Network Conference, June 2007, http://inchesnetwork.net/Lead_Venkatesh.pdf