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Sulfur An
element of the earth's crust, sulfur dusts have been used as miticides/fungicides
for centuries. Today, according the EPA, 135-190 million pounds are used
annually in U.S. agriculture. Since sulfur is a naturally occurring
material, and is relatively non-toxic to beneficials, organic and
least-toxic gardeners have come to rely on it for the control of mites,
mildew, scales, and rots.
Sulfur
is a non-metallic, insoluble element that makes up approximately 0.1% of
U.S. soils. Sulfur is mined mostly in Texas, Louisiana, and Florida, but
can also be recovered from petroleum distillation and from natural gas.
There are over 200 registrations for formulations of sulfur pesticides,
and at least five basic producers in this country. Sulfur's efficacy as a
miticide/fungicide has been found to be dependent on particle size, with
particles between 5-200 microns having the highest efficacy. Although
traditionally used as a dust, flowable liquid formulations have been
developed. Chronic
human exposure to sulfur in mines and refineries has long been known to
result in serious respiratory disturbances, including chronic bronchitis
and sinus problems. Most agricultural incidents involve skin and eye
irritations, but occasional systemic effects and deformities of the nails
have also been reported. EPA's
now defunct Pesticide Incident Monitoring System (PIMS) listed 241
poisoning incidents from 1976-1980. A third of those involved premature
worker reentry into farm fields. The California Department of Food and
Agriculture (CDFA) reported 302 poisoning incidents in 1980-1981, of which
203 were field worker poisonings. In response, California established a
24-hour waiting period for reentry into treated fields.
EPA
reviewed the rather incomplete toxicological data-set on sulfur for a
Registration Standard published in December, 1982. In this document, the
Agency reviewed a sub-chronic inhalation study in rats, noting loss of
body weight, and decreases in blood serum peroxidase, albumin, and
sulfhydryl content.
An
undated, dermal exposure study in mice reported no carcinogenic effects,
but the study was only one year long. EPA reviewers reported that sulfur
was "probably" not mutagenic.
EPA
found sulfur to be of low toxicity to bees, aquatic organisms, birds, and
fish. The Agency is not requiring submission of residue chemistry data,
given sulfur's ubiquity in the environment, and has also waived
environmental fate testing, including aquatic soil and water testing. Soil
bacteria convert the insoluble element into the sulfate ion, which is
water-soluble and can slowly leach into water. Resources: "Chemical
profile: Sulfur." Chemical Marketing Reporter. September 5,
1988. "Keeping
close tabs on sulfur," Agrichemical Age. February 1987. Gosselin,
R.E., et al. 1984. Clinical Toxicology of Commercial Products.
Williams & Wilkins, Baltimore, MD. Morgan,
D.P. 1988. Recognition & Management of Pesticide Poisonings. 4th
ed. U.S.-EPA. Washington, DC. U.S.
EPA. 1983. Guidance for the reregistration of manufacturing use and
certain end use pesticide products containing sulfur. Office of Pesticide
Programs. Washington, DC. U.S.
EPA. 1981. Pesticide incident monitoring system (PIMS) reports. Office of
Pesticide Programs. Washington, DC. Reprinted from Pesticides and You Volume 8, Number 1, March 1988
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BEYOND PESTICIDES |
