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FW: Current Issue of "JAMA": Lead Exposure From Candles

Charles Miller rellim at mailhost.tcs.tulane.edu
Mon Jul 10 10:02:39 EST 2000


----------
From: Cathy Flanders <Rkfabf at AOL.COM>
Subject: Current Issue of "JAMA": Lead Exposure From Candles

Published in the current  "Journal of the American Medical Association"

The current issue [7/12/00] of  <A
HREF="http://jama.ama-assn.org/issues/v284n2/full/jlt0712-6.html">JAMA</A>
[J
ournal of the American Medical Association]  is available on the internet
now.  This is GREAT...And will finally acquaint the Medical Community to
this 
little known source of lead exposure.  An Endocrinologist I met with this
past week had never heard of this, as a matter of fact nearly  every
physician I've encountered in the last 2 or 3 years has been completely in
the dark about this ;c)  hopefully this information in JAMA will shed some
light on this problem for mainstream health care providers ;c)

 <A HREF="http://jama.ama-assn.org/issues/v284n2/full/jlt0712-6.html">Lead
Exposure From Candles</A>
[http://jama.ama-assn.org/issues/v284n2/full/jlt0712-6.html]

Research Letters  
 
<A HREF="http://jama.ama-assn.org/issues/v284n2/full/jlt0712-6.html">Lead
Exposure From Candles</A>
 

To the Editor: Blood lead levels as low as 0.43 µmol/L (10 µg/dL) in
children 
can result in developmental and behavioral problems, including lower
intelligence.1 For this reason, lead has been restricted in paint and banned
in gasoline and vinyl miniblinds in the United States. However, most
physicians are probably unaware that household candlewicks may still include
lead as a stiffener. In 1974, the candle industry agreed with the Consumer
Product Safety Commission (CPSC) to voluntarily stop making candles with
lead-containing wicks. In February 2000, we conducted a systematic survey to
determine the prevalence of such candles. We also estimated atmospheric lead
levels produced by burning lead wick candles.
 

Methods

We purchased 1 of each type of candle with a metallic wick from 11 chain
stores and 1 dollar store in the Baltimore-Washington area and tested these
for lead by using inductively coupled plasma spectroscopy (R. J. Lee Group,
Inc, Monroeville, Pa). We then used these measured lead contents to estimate
the average 24-hour ambient air lead levels that would result from burning
these candles for 3 hours by solving the following rate equations:

(1) d l(t)/dt= -0.2  l(t) for 0t3 h

(2) d l(t)/dt=-0.2  l(t) for t>3 h

Here, 1(t) is the concentration of lead in a 51-m3 room as a function of
time,  is the rate at which lead enters the room (micrograms of lead per
centimeter of wick [determined empirically]  length of wick consumed per
hour 
[1.33 cm/hr] (written communication, K. Bridbord, MD, December 14, 1973)
fraction of lead vaporized [20%] 2, and 0.2 is the typical fraction of air
exchanged per hour in an energy-efficient home.3


Results

Eighty-six (30%) of the 285 types of candles contained metallic wicks and 9
of these (10%) contained lead, for an overall 3% lead-wick prevalence. Total
lead content per wick ranged from approximately 24,000 µg to 118,000 µg (<A
HREF="http://jama.ama-assn.org/issues/v284n2/fig_tab/jlt0712-6_t1.html">Tabl
e 
1</A>) (33%-85% lead by weight). When the rate equations are solved, these 9
candles are calculated to result in average 24-hour air lead concentrations
ranging from 15.2 to 54.0 µg/m3, which is 10.1 to 36.0 times the US
Environmental Protection Agency standard of 1.5 µg/m3.
 

Comment

Because each 1-µg/m3 increase in ambient air lead concentration in this
range 
can increase a child's blood lead level by 0.22 µmol/L (5 µg/dL),4 chronic
exposure to only 1.5 µg/m3 could raise a child's blood lead level from 0.13
µmol/L (2.7 µg/dL) (the median for US children younger than 5 years)1 to
0.48 
µmol/L (10 µg/dL), which is the upper limit recommended by the Centers for
Disease Control and Prevention. Thus, all 9 candles that we tested have at
least 10 times enough lead to achieve this increase.

We estimated that the candle containing the least lead would produce an
average air lead concentration of 30.6 µg/m3 during 3 hours of burning; a
6-year-old, inhaling 0.66 m3 of this air per hour during average daily
activity5 would exceed the CPSC's recommended daily lead limit for children
(15 µg) in 45 minutes.

According to the National Candle Association, $2.3 billion worth of candles
were projected to be sold in 1999, a figure that is increasing by 10% to 15%
annually.6 Physicians must warn patients that burning candles with
lead-containing wicks may cause lead poisoning and that there is no reliable
method to distinguish metallic candlewicks containing lead from those that
do 
not. Families exposed to candles with metallic wicks should have their blood
lead levels checked. Most importantly, the CPSC should ban and recall all
candles containing wicks with lead; we have recently filed a petition
requesting this (<A
HREF="http://www.citizen.org/hrg/PUBLICATIONS/1510.htm">ht
tp://www.citizen.org/hrg/PUBLICATIONS/1510.htm</A>).
 
Howard L. Sobel, MD, MPH, MS
Peter Lurie, MD, MPH
Sidney M. Wolfe, MD
Public Citizen's Health Research Group
Washington, DC
 

1. Centers for Disease Control and Prevention. Update: blood lead
levels—United States, 1991-1994. MMWR Morb Mortal Wkly Rep. 1997;46:141-146
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