Letters to the Editor creased by 47 percent between 1988 and 1989. As more physicians have become aware of the epidemic, fewer cases are being missed at delivery. Of the 154 symptomatic cases reported over the past three years, more than one-third of the infants had been asymptomatic at birth. In the past, failure to provide appropriate management at delivery increased the numbers of symptomatic cases. This is in sharp contrast to New York City, where Dr. Schultz and colleague imply that the number of symptomatic cases reported was decreased due to lack of adequate medical work-up and diagnosis. Perhaps New York City infants were presumptively treated when "asymptomatic". In response to an epidemic, screening efforts are generally increased. It is plausible that, in New York City, the percentage of seropositive infants subsequently counted as cases of congenital syphilis decreased due to increased screening in which the pool of false positive infants and/or previously treated serofast mothers was enlarged. If this is the case, then percentages are less valuable than absolute numbers of cases, regardless of symptoms. The current existing California law, mandating a serologic test for syphilis for pregnant women at the first provider visit or within 10 days thereafter, allows infected infants to be missed at delivery. The recent law in New York to perform serologic test for syphilis on all newborns at delivery is a positive step in ensuring consistent monitoring of congenital syphilis trends. Unless California and other high incidence states follow suit, we will never truly know the entire scope of the syphilis problem. And unless there is a consistent and uniform effort to continue effective screening programs, we will never know if epidemic control is real or an artifact. [] Deborah A. Cohen, MD, MPH Lawene Mawoa, MD, MPH Dr. Cohen is with University of Southern California, Department of Family Medicine, 1420

San Pablo Street, Los Angeles, CA 90033. Dr. Mascola is with Los Angeles County Department of Health Services.

References 1. Htoo M, Schultz S: Congenital syphilis criteria. (Letter) Am J Public Health 1991;

81:111. 2. Cohen D, Boyd D, Prabhudas I, Mascola L: The effects of case definition, maternal screening, and reporting criteria on rates of congenital syphilis. Am J Public Health 1990; 80:316-317. 3. Centers for Disease Control: Guidelines for

514 American Joumal of Public Health

the prevention and control of congenital syphilis. MMWR 1988; 37 (suppl # S-1). 4. Centers for Disease Control: Congenital syphilis-New York City, 1986-1988. MMWR 1989; 38:825-829.

Editor's Note: The Journal regrets that this letter from Drs. Cohen and Mascola was not included in the letters on congenital syphilis criteria published in the January 1991 issue (pp 111-112.

Lead Exposure in Sandblasfing With respect to the correspondence in this Journal concerning exposure to lead in sandblasting,' and the possibility that this exposure may have contributed to the excess risk of end stage renal disease reported by Steenland, et al,2 I would like to add the following information to that from Schirmer. According to a recent report by EPA on mining wastes, waste material from lead mines is sold as material for sandblasting.3 This material, finely ground slag and other wastes, can contain lead in concentrations of parts per hundred. Thus it is possible that sandblasters could have exposures to lead that exceed those of workers in identified lead industries, particularly under conditions where "environmental" protections are taken, such as draping and enclosing the site, measures that may reduce releases of lead but tend to increase worker exposure. Given the federal government's passivity on this subject, state and local public health officials may wish to take steps to prevent this dangerous material from use. It is not enough that construction and demolition operations may result in lead exposure and release; if lead-containing materials are used in the process, this exposure may occur even at sites where no lead paint is present. El Ellen K. Sileld PhD Visiting Professor of Toxicology and Adjunct Professor of Pharmacology and Experimental Therapeutics, University of Maryland at Baltimore, University Program in Toxicology, 660 West Redwood Street, Howard Hall, Rm 544, Baltimore, MD 21201.

References 1. Schirmer J: Lead risks overlooked in sandblasters? (letter) Am J Public Health 1990; 80:1275-1276 (and response from Steenland and Thun). 2. Steenland K, Thun MJ, Ferguson CW, Port FK: Occupational and other exposures as-

sociated with male end stage renal disease: A case/control study. Am J Public Health 1990; 80:153-157.

3. US Environmental Protection Agency: Report to Congress on Mining Wastes. Wash-

ington, DC: Office of Solid Waste and Emergency Response, 1990; 10-33.

Response from Schirner Dr. Silbergeld has made an important point concerning the use of lead contaminated mining slag as a sandblasting agent. Since not all readers may appreciate the significance of contamination concentrations in the percentage range, 1 percent is equivalent to 10,000 parts per million. In comparison, soil is considered to result in increasing lead doses to children at concentrations above 500 parts per million.1 There are now three sources which may generate lead in air during sandblasting: the blasting agent, the material to be blasted (e.g. leaded brass), or lead paint still used to coat metal and used in the past on wood and brick. All of these sources may generate lead concentrations during sandblasting which threaten sandblasters or the public at large. Steenland, et al, assumed silica rather than lead to be the agent associated with excess end stage kidney disease in sandblasters.2 This may indeed prove to be valid; silica may be linked to kidney disease. However, kidney damage may also occur to sandblasters as a result of lead exposure and lead exposures to sandblasters are likely to be more severe than those experienced by other "lead-exposed" workers. For example, industrial hygiene measurements from the state of Maryland indicate that lead exposure to sandblasters working on structural steel coated with lead paint range from 1,072 to 10,420 micrograms per cubic meter or from 21 to 208 times greater than the permissible exposure limit set by federal OSHA for industrial workers.3 To visualize this hazard, consider that sandblasting a typical standard sized 500,000 gallon water tower coated with 10 percent lead paint would require the removal of 246 pounds of lead.4 This is significant since the toxic effects of lead begin with exposures measured at microgram concentrations of lead per cubic meter of air. Similarly, Froines, et al, examined OSHA lead inspection data from 1979 to 1985 and found higher lead exposures in bridge, tunnel, and elevated highway construction than in industries typically considered lead-exposed such as battery manufacturing, radiator repair or non-ferrous foundries.5 Painters in machinery manufacture (SIC 35) and transportation equipment manufacture (SIC 37) were also at high risk for lead exposure.

April 1991, Vol. 81, No. 4

Lead exposure in sandblasting.

Letters to the Editor creased by 47 percent between 1988 and 1989. As more physicians have become aware of the epidemic, fewer cases are being missed...
254KB Sizes 0 Downloads 0 Views