On 15 January the US Environmental
Protection Agency's (EPA) Office of Pesticides
Program (OPP) reported disturbing acute and
chronic adverse effects stemming from misuse and
misapplication of chlorpyrifos by householders
and professional pesticide applicators(1). It
also questions pest control operators'
application and safety practices in general and
suggests that the leading registrant of
chlorpyrifos products, DowElanco, may have
incorrectly stated the risks associated with
Dursban (chlorpyrifos) use. The review concludes:
"The percentages for life threatening cases
appear higher for chlorpyrifos and some of this
may be due to the more concentrated products used
by pest control operators."
Nervous system effects of
chlorpyrifos poisoning listed in the review were
confusion, anxiety, drowsiness, depression,
difficulty concentrating, slurred speech, poor
recall, insomnia, nightmares, emotional lability
(instability), or a form of toxic psychosis
resulting in bizarre behaviour.
The OPP
review was released on the same day that
DowElanco and EPA said they had agreed on a
10-point plan to mitigate risks from chlorpyrifos
use, including withdrawal of several Dursban
broadcast flea control and total release fogger
products, as well as withdrawal of several of the
company's chlorpyrifos shampoos, dips and
sprays(2).
A study by Dr Janette Sherman,
an independent physician from Alexandria,
Virginia, in the US has linked birth defects seen
in children to their mothers' exposure to an
organophosphate (OP) pesticide during the first
three months of their pregnancy. Dr Sherman
presented evidence at a New York meeting of the
American Public Health Association in New
York(3). In a recent paper(4) she has published
her findings that the chlorpyrifos formulation
Dursban, made by DowElanco, is linked to deformed
heads, faces, eyes and genitals, and the affected
children require constant care.
More allegations are made by
Albert Donnay, Executive Director of the
Baltimore Group MCS Referral & Resources,
citing data from the National Pesticide
Telecommunications Network (NPTN); registration
data on the adverse effects of Dursban submitted
by the manufacturers; and reports from doctors
working with MCS patients.
The NPTN log is a record of
complaint calls from 1984-1990 under the heading
'Listing of peripheral neuropathy active
ingredients, as noted by NPTN operators'. It
lists 161 reports of MCS due to chlorpyrifos
exposure as reported by callers and 21 complaints
of peripheral neuropathy. The NPTN log is not
evidence of causation.
The analysis of 1,100 pages of
data from DowElanco, manufacturer of
chlorpyrifos, lists over 450 adults and children
who were poisoned by the pesticide in their home
or workplace.
Chlorpyrifos was the most
frequently cited active ingredient in respect of
MCS calls-the next most frequent were the OPs
diazinon and malathion and the carbamate
bendiocarb-and the second most frequently cited
by peripheral neuropathy callers.
In response to these studies, a
national coalition of five environmental
organisations is calling on the US EPA to issue
emergency regulations restricting the use of
Dursban, one of the most widely used household
and agricultural insecticides in the US(5). The
coalition is asking EPA to:
The analysis of the data is disputed by manufacturers, which also challenge the existence of MCS. The State of California is also reviewing chlorpyrifos but has not yet found anything to trigger taking additional risk reduction measures. The US EPA concludes the available evidence does not support a finding of teratogenicity (birth defects) based on human epidemiology studies and case reports.
The UK position
Chlorpyrifos has been on the market for thirty
years. One of DowElanco's three global production
sites is based in Kings Lynn, Norfolk. In the UK
it is mainly used as an insecticide on wheat and
top fruit. It is also used in commercial food
preparation areas, as a household insecticide and
on sports turf. In 1994, farm usage was 1,800
tonnes applied on nearly 350,000 ha(6). About
8,400 pounds (3,800 kg) of chlorpyrifos were used
in the Gulf War by both the British and US
troops.
Chlorpyrifos has not been a
major source of concern in terms of poisoning
incidents compared with other OPs. It is not used
as widely in home situations as in the US.
Nevertheless, data from the Health and Safety
Executive Annual Incidents database shows that in
1994-95, three poisoning cases concerned the
agricultural use of chlorpyrifos, two of which
involved hospital treatment.
In these circumstances the
Pesticides Trust [now PAN UK] is contacting the Advisory
Committee on Pesticides, the independent body
that advises ministers, to press the case for an
urgent review of the safety of chlorpyrifos. (PB)
1. Blondell, J and Dobzy, V., Review of Chlorpyrifos Poisoning Data, Special Review, EPA, January 1997.
2. Chlorpyrifos misuse, chronic effects such as MCS highlighted in EPA OPP review, Pesticide and Toxic Chemical News, 22 January, 1997.
3. Chlorpyrifos link to multiple chemical sensitivity, birth defects spurs call for restrictions on use, Pesticide & Toxic Chemical News 27 November 1996.
4. Sherman, J.D., Chlorpyrifos (Dursban)-Associated with birth defects: a proposed syndrome, report of four cases and a discussion of the toxicology, International Journal of Occupational Medicine and Toxicology, 1995, 44, 417-31.
5. The environmental coalition: Environmental Working Group, Mothers and Others for a Liveable Planet, National Coalition Against the Misuse of Pesticides, New York Coalition for Alternatives to Pesticides, Northwest Coalition for Alternatives to Pesticides, Pestic
ide Action Network North America, Rachel Carson Council.
6. Pesticide Usage Survey Report 100. Review of usage of pesticides in agriculture and horticulture throughout Great Britain 1984-94. MAFF Publications, London, 1997. 19pp. £4.
[This
article first appeared in Pesticides News No. 35,
March 1997, page 3]