ACR: Bug Sprays Linked to RA

[Guest guest]

ACR: Bug Sprays Linked to RA

By Gever, Senior Editor, MedPage Today

Published: October 22, 2009

Reviewed by _Dori F. Zaleznik, MD_

(http://www.medpagetoday.com/reviewer.cfm?reviewerid=512) ; Associate Clinical

Professor of Medicine, Harvard

Medical School, Boston and

Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner _Earn CME/CE credit

for reading medical news_

(http://www.medpagetoday.com/posttest.cfm?testpage=16572 & TBID=16572 & topicid=233)

Action Points

____________________________________

* Explain to interested patients that they should follow label

directions when using household insecticides and other toxic chemicals.

* Note that this study was published as an abstract and presented at

a conference. These data and conclusions should be considered preliminary

until published in a peer-reviewed journal.

PHILADELPHIA -- Women who frequently sprayed their homes with insecticides

over a period of years may have put themselves at risk for autoimmune

diseases such as rheumatoid arthritis and systemic lupus erythematosus, a

researcher said here.

Among women who sprayed at least six times a year, the risk of autoimmune

disease was more than twice that of women who didn't use insecticides (HR

2.47, 95% CI 1.51 to 4.03, P=0.0036).

The results were similar among women who used insecticides for 20 years or

more (HR 2.07, 95% CI 1.31 to 3.25), according to G. Parks, PhD,

an epidemiologist with the National Institute of Environmental Health

Sciences in Research Triangle Park, North Carolina.

" We also saw that long-term application of insecticides by others in the

home or in the lawn or garden about doubled disease risk, " she told

attendees at the American College of Rheumatology's annual meeting.

She found almost the same risk of autoimmune disease among women from

environments with long-term insecticide spraying by commercial companies (HR

1.85, 95% CI 1.13 to 3.04).

The researchers examined records of 76,861 postmenopausal and

predominantly white women ages 50-79 enrolled in the Women's Health Initiative

Observational Study. Parks and colleagues focused on questions relating to farm

history and insecticide use.

Of those whose records were reviewed, 178 later were eventually diagnosed

with rheumatoid arthritis and 28 with lupus. An additional seven women were

diagnosed with both lupus and rheumatoid arthritis.

Parks said investigators found that a history of just working or living on

a farm -- although relatively frequent among the women in the survey --

did not appear to increase risk of rheumatoid arthritis or lupus.

But compared to people who had never used insecticides, women who had

personally mixed or applied insecticides regularly had double the risk of a

rheumatic disease.

" About 46% of the rheumatoid arthritis cases occurred among women who

mixed or applied insecticides themselves, " Parks said.

The relationships held when the data were adjusted for farm history, age,

race, ethnicity, education, occupation, smoking, and other risk factors for

disease, she said.

Parks cited studies showing that up to 75% of U.S. households use

insecticides in the home or garden, with 20% of householders reporting that

they

had applied insecticide in the month before being surveyed. She also noted

that insecticides don't break down readily in the home environment.

" Our results also provide support for the idea that environmental factors

may increase susceptibility or trigger the development of autoimmune

diseases in some individuals, " said Parks. " We need to start thinking about

what

chemicals or other factors related to insecticide use could explain these

findings. "

She said that her study was limited because the questions asked about

insecticides did not deal with specific products.

" It is important to note that these are still relatively uncommon diseases

affecting only a small percentage of adults, but I believe it provides

proof of principle that these environmental exposures may be risk factors that

need to be studied more thoroughly, " she said.

" Although our findings are not proof of a causal relationship with

products currently on the market and available for household use, " Parks said,

" I

think the take-home message is that people should always follow recommended

practices to reduce their individual exposures. "

Darcy Majka, MD, an assistant professor of medicine at Northwestern

University in Chicago, said that " the findings are fairly compelling because

Dr.

Parks did find a dose response. "

" The study is also hypothesis-generating: Is it skin exposure? Is it

inhalants? Further studies are needed, " she said.