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Recently, environmental groups have cited an article in the May 22nd issue of Science News (Volume 143) as indicating that cement plant HWF operations are harmful to human health and the environment. The article very briefly summarizes five papers that were given at a recent hazardous waste health effects conference held in Atlanta.
The article leads readers to believe that respiratory and neurological problems have been definitively linked to working at, or living near, hazardous waste incinerators. This is simply not the case. Three of the five studies concentrated on workers from facilities that had been shut down at the time of the study. One of these studies, conducted by Kawamoto from NIOSH in Cincinnati, was the only study that was designed to include medical evaluations by internists and neurologists, plus psychological evaluations by psychiatrists. A movement disorder specialist was also involved, and special efforts were made to design bias out of the investigation. Even given the well thought out comprehensive design of the Kawamoto study, the study concludes:
"The most frequently reported symptoms were nonspecific (that is, they could be easily caused by any of a number of factors, including, but not limited to, chemical exposures).... All participants had psychiatric symptoms, but the diagnoses with sufficient supporting information were not the same, and no specific work-related syndrome was observed." The report summary goes on to say, "The September 1990 evaluations did not demonstrate a high prevalence of any objectively quantifiable findings that could be used as part of a specific case definition to evaluate other Caldwell employees. Without such a case definition, a valid epidemiological study to determine whether the reported health conditions could be associated with work exposures was not feasible."
A second study associated with this same closed facility, cited in this article, conducted by Straight from the Agency for Toxic Study and Disease Registry (ATSDR) in Atlanta, is a draft report that has only been released for public comment. This study did not include comprehensive medical and psychological examinations. It relied almost exclusively on responses to questionnaires.
The draft write-up points out that "Recall bias, another type of information bias, is also inherent in all retrospective studies, especially those involving well publicized environmental exposures. Recall bias was of concern because two years had elapsed between the closing of the incinerator and the field portion of the study, and 14 years had elapsed since the start of incinerator operation." Additionally, where medical information was used to corroborate questionnaire findings, as stated in conclusion #2, "Neither physician-diagnosed diseases nor hospital admissions for these diseases differed in prevalence between the target and comparison areas."
The Science News article leads readers to believe that because "The closer community [to the closed incinerator] reported almost nine times more coughing and wheezing, 2.4 times as much neurological disease...and 40 percent more neurological symptoms...." that this was in some way caused by the incinerator. What Science News fails to point out is that:
"Persons who reported current health problems thought to be caused by chemicals in or near the home were five times as likely to report respiratory symptoms as persons who did not report such health problems...." These people were "...twice as likely...to report diagnosed respiratory disease...." (as opposed to just the symptoms). The ATSDR draft report also points out that "Self-reported symptoms may be affected by a variety of factors, including difficulty recalling minor symptoms, determining when symptoms started and stopped, or determining how much significance was attached to a symptom when it occurred."
The ATSDR draft report lists seven conclusions. The final conclusion is quoted as follows: "7. As the study objective stated, this type of study is not designed to determine a causal association between environmental exposure and health outcomes, even though significant differences were found between the target and comparison areas."
The third study associated with a closed facility was originally conducted in 1988, but the participation rate was so low that the results were not published until now, in conjunction with this health effects conference, over five years later. This study makes the strongest inferences of the health effects associated with handling waste torpedo fuel containing a form of cyanide, an activity not found at any cement plant burning waste fuel. This study was conducted by Stopford of Duke University Medical Center in Durham, N.C. who is planning additional studies of workers not exposed to the waste torpedo fuel as a comparison group.
A key factor which is not brought out in the Science News article, is that the Kawamoto and Straight studies involved incinerators that were poorly operated. These incinerators appear to have been operated without proper regard to employee health and safety. These incinerators should have been shut down and ultimately were shut down.
It seems apparent that the Caldwell and Mitchell incinerators were not very well run from a health and safety standpoint. As an example, the facility regularly handled waste torpedo fuel, approximately eight percent of the waste processed, which contained propylene glycol dinitrate, 2-nitrodiphenylamine and dibutyl sebucate. Traces of cyanide gas were also present in the fuel. This type of material has repeatedly been rejected for consideration as waste fuel for cement kilns due to the relatively high toxicity.
These reports are already being cited by environmentalist groups as proving that life around an incinerator is unhealthy. They could more accurately be described as studies of poorly operated facilities that did not take proper safety and health precautions. Not readily discernable from the study is whether the waste processed in the incinerator (not a cement kiln) was over chlorinated. Even given all of that, dairy cattle pastured on an adjacent dairy farm revealed blood lead and serum dioxin and furan levels below published normal values for cattle. (emphasis added)