Common Weed Killers Affect Developing Fetus

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Common Weed Killers Affect Developing Fetus

 

Damage to Fetus Can Happen in Early Pregnancy

 

By Jeanie Lerche Davis

WebMD Medical News

on Monday, May 24, 2004

 

 

May 24, 2004 -- Common lawn care products can cause developmental

problems in early pregnancy -- just days after conception, new research

shows.

 

Exposure to newly treated lawns and golf courses -- before the recommended

waiting period is over -- could harm the developing embryo, researchers say.

Weed-B-Gon, Scott's 4XD, and Atrazine are just three products found to cause

harm.

 

" Even extremely low concentrations of these pesticides -- concentrations

thought to not cause any harm if the person ingests it -- could interfere

with

both conception and an embryo's implantation in the uterus, " researcher Anne

Greenlee, PhD, a research scientist with the Reproductive Toxicology

Laboratory at

the Marshfield Clinic Research Foundation in Wisconsin, tells WebMD.

 

Her study appears in the May issue of Environmental Health Perspectives.

 

Findings 'Unquestionably Worrisome' The EPA has asked to review her findings.

 

The information may be included in new labeling for products containing

2,4-Dichlorophenoxyacetic acid (2,4-D), a commonly used lawn care herbicide.

 

" They realized they had very little information about these products on the

fetus in [early pregnancy], and want to include the information we had on the

 

package, " Greenlee says.

 

At the EPA, Mark Seaton, PhD, is a chemical review manager heading up

re-registration of herbicide 2,4-D. " Any time I see something about 2,4-D, I

pay

attention. I've made the team's toxicologist aware of the study. "

 

" This is yet another in a worrisome, very substantial series of reports which

 

suggest the in utero effects of these quite common pesticides and

herbicides, " Roberta Ness, MD, MPH, chair of epidemiology at the University

of Pittsburgh

Graduate School of Public Health, tells WebMD. She commented on Greenlee's

findings.

 

" A number of animal studies have shown congenital malformations, abortion,

and interference with neurological development, " Ness says.

 

" This has been shown in a less rigorous way in humans -- in migrant farmer

workers and other occupations where exposures have been more extreme. There

has

been very, very few good human studies that have allowed us to look at normal

 

levels of pesticide exposure. "

 

Greenlee's findings are " unquestionably worrisome but not completely

surprising, " she adds.

 

Women who are trying to get pregnant need to do homework: Find out what

products their neighbors and greenskeepers use, says Greenlee.

 

For specific information about hazards of specific herbicide products,

Greenlee advises checking the National Pesticide Information Center web site

provided by Oregon State University and the EPA at npic.orst.edu.

 

Common Herbicide

 

Herbicides such as 2,4-D are used to control broad-leaf weeds in agriculture

and for control of woody plants along roadsides, railways, and utilities'

rights of way, according to the EPA. They are also widely used on such crops

as

wheat and corn, and on pasture- and rangelands.

 

Home lawns and golf greenways are all treated with similar herbicides,

Greenlee adds.

 

Pesticide manufacturers are required to conduct health studies of the effects

 

of these herbicides on reproduction. The safest exposures and safety hazards

are provided on product labels. However, this very early time period in fetal

 

development has not been investigated, she tells WebMD.

 

Studies have detected these pesticides in human ovarian fluid, fluid from

semen, human amniotic fluid, and even in fluids that surround the human

newborn,

she notes.

 

In a previous two-year study, Greenlee investigated effects of pesticides and

 

fungicides in women who mix and apply these chemicals. She found that women

doing this kind of work were 27 times more likely to have fertility problems

compared with pregnant women who didn't work with these chemicals.

 

In her current study, Greenlee sought to explain how the chemicals affected

early pregnancy.

 

Mouse Embryos Mirror Humans

 

Newly conceived mice -- embryos that were just five days old -- were the

subjects of her study.

 

In the first week after fertilization, the fetus has not yet become implanted

 

in the mother's uterus. It's a phase of development that is similar to early

pregnancy in humans, Greenlee explains. During the first to seventh day of

pregnancy, the embryo is rapidly dividing and preparing to implant in the

mother.

 

In a series of experiments, Greenlee exposed these tiny fetuses to extremely

low doses of herbicides, insecticides, fungicides, and fertilizers used in

lawn care and agriculture. She exposed them to individual chemicals and to

mixtures of chemicals.

 

The exposures simulated typical human exposures when the chemicals are

touched or inhaled.

 

Her discovery: 12 of 13 chemicals and all six chemical mixtures caused

developmental injury prior to implantation, she writes. Some chemicals slowed

 

embryonic development while others decreased the numbers of cells produced in

the

embryo. " These embryos wouldn't develop normally, " she tells WebMD.

 

Only one chemical -- permethrin -- had no measurable effects on early

pregnancy, Greenlee adds.

 

Greenlee stresses it is important that additional work be done to validate

these findings in humans and to assess the real risks to pregnancy.

 

Advice for Mothers-to-Be

 

" It's going to be difficult to come up with hard-and-fast advisories for

women, " Greenlee tells WebMD.

 

All herbicides go through two risk reviews at the EPA -- a human health and

an environmental " fate and effects " assessment that includes plant life,

other

mammals, and aquatic life, says Seaton. Those reviews are scheduled for

public

comment in late June.

 

Bottom line: Whatever can be done to minimize exposure, do it. If you're

planning to conceive, or trying to conceive, minimize your exposure during

early

pregnancy. Read product labels and adhere to safety guidelines.

 

" Women considering or trying to conceive should make every effort to minimize

 

their exposure to lawn care and agrochemical products, " Greenlee writes.

" Applying these products according to label guidelines and wearing protective

 

gear, such as masks or gloves, can help reduce exposure. It's also important

to

adhere to the length of time manufacturers recommend you stay off your lawn

or

field after using pesticides, herbicides, and fertilizers " she advises