Recall bias in disease status associated with perceived exposure to hazardous substances.

Recall bias was assessed in a study of cancers reported by persons living in a community with a hazardous waste treatment facility (A) and a control community (B). The self-reported cancers were verified against medical records and pathology reports. Of the 56 cancer cases reported, 43 were in community A and 13 were in community B. The difference in incorrect reporting of neoplasms between community A and community B was 12% for neoplasms and 23% for malignancies. Before verification, there was a borderline significant association (P = 0.049) between living in community A and all self-reported cancers [odds ratio (OR) 1.88, 95% confidence interval 0.99-3.57]. The verified data showed that ORs decreased with the increasing precision of diagnosis. The effect of misclassification on the OR was an inflation by 15% for neoplasms and by 31% for malignancies. The results demonstrate the importance of verifying reported cases of disease, even a disease as well defined as cancer.

Factors affecting in vivo measurement precision and accuracy of 109Cd K x-ray fluorescence measurements.

109Cd K x-ray fluorescence (XRF) measurement systems from two research centres were used to measure tibia lead content in a population (n = 530) of young adults. The group mean bone lead contents (+/-SEM) determined by McMaster University (n = 214) and the University of Maryland (n = 316) were 2.80 +/- 0.51 and 2.33 +/- 0.50 microg Pb/(g bone mineral) respectively. The mean difference of 0.47 +/- 0.71 microg Pb/(g bone mineral) was not significant. There was no evidence of a systematic difference between measurements from the two systems. Measurement uncertainties for the young adults were poorer overall than uncertainties for a population of occupationally exposed men. This was because obese subjects and women were included in the study. Regressions of precision against body mass index (BMI, defined as weight/height2) determined that uncertainties increased with BMI and were poorer for women than men. Measurement uncertainties (1sigma) were >8 microg Pb/(g bone mineral) for women with a BMI > 0.004 kg cm(-2). Poor-precision data affected population estimates of bone lead content; an inverse correlation was found between precision and bone lead content. A small number (0.4%) of individual measurements with poor uncertainties were inaccurate to within the precision. It is suggested that obese subjects, whose BMI > 0.004 kg cm(-2), should be excluded from 109Cd K XRF studies, as the measurement provides limited information and may be inaccurate.

Assessment of reproductive disorders and birth defects in communities near hazardous chemical sites. I. Birth defects and developmental disorders.

Members of the workgroup on birth defects and developmental disorders discussed methods to assess structural anomalies, genetic changes and mutations, fetal and infant mortality, functional deficits, and impaired fetal and neonatal growth. Tier 1 assessments for all five adverse reproductive outcomes consist of questionnaires and reviews of medical records rather than laboratory testing of biologic specimens. The work-group members noted a role for neurodevelopmental testing and for limited genetic studies, such as karyotyping in Tier 2 assessments. Emerging methodologies to identify chromosomal aberrations, DNA adducts, and repair inhibition were reserved for Tier 3.

Public health risks of railroad hazardous substance emergency events.

The number of railroad events reported to the Agency for Toxic Substances and Disease Registry's Hazardous Substances Emergency Events Surveillance system increased from 84 in 1993 to 177 in 1998. Comparisons of data on railroad and non-railroad events were made. The results overall indicated a greater potential impact of railroad events on public health. A median number of 2039 persons were living within a 1-mile radius of railroad events versus 982 for non-railroad events. The percentage of events during times when people are more likely to be home was also greater for railroad events. Railroad event victims were more likely to need hospital treatment than non-railroad event victims, which suggested the need for better community planning, reevaluation of current federal regulations and priorities for railroad hazardous material transport, and enhanced railroad industry commitment to safety.

Frequency and type of injuries in responders of hazardous substances emergency events, 1996 to 1998.

This analysis describes the frequency and type of injuries among responders to hazardous materials releases. Data were analyzed from states that participated in the Hazardous Substances Emergency Events Surveillance system maintained by the Agency for Toxic Substances and Disease Registry from 1996 through 1998. A total of 348 responders were injured in 126 (0.7%) of 16,986 reported events. Firefighters and police officers were most often injured. Respiratory irritation and nausea were the most commonly reported injuries, and no injuries resulted in death. Almost half of the responder victims wore firefighter turn-out gear, and about a third had received hazardous materials training. Chemicals frequently released during these events were in the category "other substances not otherwise specified" and "acids." Training, education, planning, and coordination are needed to effectively respond to hazardous substances emergency events.

Health effects related to releases of hazardous substances on the Superfund priority list.

The Agency for Toxic Substances and Disease Registry maintains an active, state-based surveillance system to record the public health consequences of hazardous substance releases. During 1992, the 9 participating states reported 1,876 events; 80% of the events occurred at fixed facilities, and 20% were transportation related. The most frequently released substances were volatile organic compounds, acids, herbicides, and ammonia. In 263 events, 600 people were injured and 4 died. Employees were injured more frequently (71%) than first responders or the general public. The most frequently reported injuries were respiratory and eye irritation. Evacuations occurred in 13% of the events. These results provide information for preparedness planning and training of first responders and employees.

Exposure registries.

Exposure registries are new tools for use as part of the public health response to toxic occupational and environmental exposures. These registries can help fill a gap that currently exists in the effective handling of problems following the revelation of an exposure situation. In the past, such a tool was lacking and potentially high-risk groups may not have received needed services. Recent legislation, however, has mandated the establishment of exposure registries. These registries can help provide the basis for a unified response to what historically has been described as a fragmented and ineffective approach to managing high-risk cohorts and assessing the impact of toxic substances. Certain exposure registries are now mandated by law (PL 96-510), and they have a place alongside other disease control and public health tools. Their establishment and use is not without problems, but the gain from them could be substantial. They fill a gap in the current public health response to problems of groups found to be at increased risk of exposure to toxic substances.

New ceramics-related industry implicated in elevated blood lead levels in children.

Elevated lead levels have been implicated as a cause of a variety of health problems in children. Blood lead, erythrocyte protoporphyrin, and hemoglobin levels were measured for family members of workers exposed to lead borosilicate dust in a capacitor and resistor plant in Colorado. Previous studies in other lead-related industries have shown an increased risk of lead poisoning among workers' children through exposure to dust brought home on work clothes. Eighty-nine family members of 41 exposed workers were tested along with 62 family members of 30 unexposed comparison households. The mean blood lead level in the family members of exposed workers was significantly elevated compared with that of the unexposed group (10.2 vs. 6.2 micrograms/dl, p = .0001).

Data linkage to explore the risk of low birthweight associated with maternal proximity to hazardous waste sites from the National Priorities List.

Data from the 1988 National Maternal and Infant Health Survey files were linked with data from the 1990 Environmental Protection Agency National Priorities List of hazardous waste sites to determine whether any relationship existed between living in proximity to hazardous waste sites and low birthweight. The odds ratio for low birthweight versus normal birthweight was 1.03 (95% confidence interval [95% CI] = 0.98-1.16), and remained at 0.99 (95% CI = 0.86-1.16) when adjusted for maternal age, parity, infant sex, prenatal care, and behavioral and socioeconomic factors. Very low birthweight, infant and fetal death, prematurity, and congenital malformation were not found to be associated with living in the vicinity of a hazardous waste site during pregnancy. Merging a large population database with environmental data proved to be an innovative but not very efficient method of assessing the risks of low birthweight related to the environment.

Recent chemical exposures and blood volatile organic compound levels in a large population-based sample.

Little is known about factors that influence blood levels of volatile organic compounds in nonoccupationally exposed populations. The authors examined the possible relationship between recent self-reported chemical exposures and elevated blood volatile organic compound levels among 982 adult participants in theThird National Health and Nutrition Examination Survey. A strong dose-response effect was indicated (p < .001) for increasing lifetime pack-years of cigarettes smoked for elevated levels of toluene, styrene, and benzene. A positive dose-response effect was indicated for daily alcohol consumption with respect to elevated blood levels of 2-butanone and acetone. For volatile organic compounds typically found in 10-75% of the population, the establishment of a link with specific environmental exposures is relatively easy because there is less effect of confounding in this group. Some volatile organic compounds, however, are seen in less than 10% of the general population; finding these compounds at any level may warrant a search for a particular exposure.

Surveillance of hazardous substance releases and related health effects.

The public health consequences of hazardous substance releases have not been characterized adequately. In response, therefore, the Agency for Toxic Substances and Disease Registry implemented an active, state-based surveillance system. Information is collected with respect to the events, chemicals, victims, injuries, and evacuations. Five states reported 1,249 events during 1990 and 1991. Seventy-two percent of the events occurred at fixed facilities, and 28% of the events were transportation related. In 80% of the events, one chemical was released. The most frequently released chemicals were herbicides, acids, volatile organic compounds, and ammonias. In 204 events, 846 persons were injured and 7 died. Employees were injured more frequently than first responders or the general public. The most frequently reported injuries were respiratory irritation and eye irritation. Evacuations occurred in 14% of the events. These results provide information for preparedness planning and training of first responders and employees.

Use of exposure databases for status and trends analysis.

Exposure databases are useful for monitoring status and trends in environmental health. However, other supporting data are usually needed to infer human exposure or internal dose. Program planning and evaluation, environmental health surveillance, epidemiologic research, and contributions to international efforts are four major purposes for monitoring environmental exposure status and trends. Although databases play an important role in monitoring human exposure, certain methodological problems need to be overcome. The work group developed six criteria for meeting information needs for human exposure assessment. Areas that need attention are (1) specification of location, (2) specification of facility and chemical identifiers, (3) documentation of special populations at risk, (4) provision of early warning of new problems, (5) monitoring changes over time, and (6) enhancement of documentation. We tested these criteria by examining six available databases that might be used for monitoring exposure to contaminants in drinking water. Available data fell short of information needs. We drew four conclusions and offered several recommendations for each. First, available data systems lack adequate measures of human exposure. Second, data for monitoring exposures for many important population subgroups and environmental settings are inadequate. Third, an "early warning" system that monitors human exposures is needed. Fourth, designers of data-collection systems should consider the needs of users who monitor status and trends of human exposure.

Tetrachloroethylene in drinking water and birth outcomes at the US Marine Corps Base at Camp Lejeune, North Carolina.

A study of mean birth weight, small-for-gestational-age infants, and preterm birth was conducted at the US Marine Corps Base at Camp Lejeune, North Carolina, where drinking water was contaminated with volatile organic compounds. Tetrachloroethylene (PCE) was the predominant contaminant. The authors used multiple linear and logistic regression to analyze 1968-1985 data from 11,798 birth certificates. Overall, at most weak associations were observed between PCE exposure and study outcomes. However, associations were found between PCE exposure and birth-weight outcomes for infants of older mothers and mothers with histories of fetal loss. Adjusted mean birth-weight differences between PCE-exposed and unexposed infants were -130 g (90% confidence interval (CI): -236, -23) for mothers aged 35 years or older and -104 g (90% CI: -174, -34) for mothers with two or more previous fetal losses. Adjusted odds ratios for PCE exposure and small-for-gestational-age infants were 2.1 (90% CI: 0.9, 4.9) for older mothers and 2.5 (90% CI: 1.5, 4.3) for mothers with two or more prior fetal losses. These results suggest that some fetuses may be more vulnerable than others to chemical insult.

A case-control study to determine risk factors for elevated blood lead levels in children, Idaho.

OBJECTIVE: A pair-matched, case-control study was conducted to identify if risk factors or behaviors suspected to affect childhood blood lead levels, were more prevalent among children with elevated blood lead levels living in the vicinity of a defunct mining and smelting facility. METHODS: Study individuals were recruited from the 1992 Silver Valley blood lead screening participants. The cases were children with a blood lead level > 10 micrograms per deciliter (microgram/dL). The controls were children with a blood lead level < 10 micrograms/dL, who were matched to cases by age and sex. Data on risk factors were obtained through personal interviews. RESULTS: Of the variables examined, yard soil remediation showed the strongest association with changes in blood lead levels. This variable was found to be a protective factor for elevated blood lead levels in children (odds ratio, 0.28; confidence interval, 0.08-0.92). CONCLUSION: The results suggest that removal of lead contaminated soil from residential yards was effective in reducing blood lead levels in children.

Cluster: a software system for epidemiologic cluster analysis.

A software package for cluster analysis was developed that incorporates 12 methods to analyse residence and time data, and morbidity or mortality rates. The Knox, Barton, Chen and Ohno methods of the software are illustrated with data for 123 cancer cases reported by a citizen requesting a cluster investigation. Longitude and latitude for each address were assigned by a geographic information system for analyses with the Barton (p > 0.05) and Knox methods (p > 0.05). The data were also analysed for time of the event with the Chen method, comparing the observed incidence to expected county disease rates (p = 0.61), and for temporal patterns within the geographically defined population with the Ohno method (p >0.05). It was concluded that no statistically significant disease cluster existed.

109Cd K x ray fluorescence measurements of tibial lead content in young adults exposed to lead in early childhood.

OBJECTIVES: Tibia lead measurements were performed in a population of 19-29 year old people who had been highly exposed to lead in childhood to find whether lead had persisted in the bone matrix until adulthood. METHODS: (109)Cd K x ray fluorescence was used to measure the tibia lead concentrations of 262 exposed subjects and 268 age and sex matched controls. Questionnaire data allowed a years of residence index to be calculated for exposed subjects. A cumulative blood lead index was calculated from the time weighted integration of available data of blood lead. RESULTS: The mean (SEM) difference between exposed and control men was 4.51 (0.35) micrograms Pb/g bone mineral, and between exposed and control women was 3.94 (0. 61) micrograms Pb/g bone mineral. Grouped mean bone lead concentrations of exposed subjects were predicted best by age. When exposed and control subjects' data were combined, grouped mean bone lead concentrations were predicted best by cumulative blood lead index. The years of residence index was neither a good predictor of bone lead concentrations for exposed subjects nor for exposed and control subjects combined. Finally, exposed subjects had increased current blood lead concentrations that correlated significantly with bone lead values. CONCLUSION: Bone lead concentrations of exposed subjects were significantly increased compared with those of control subjects. Lead from exposure in early childhood had persisted in the bone matrix until adulthood. Exposed subjects had increased blood lead concentrations compared with controls. Some of this exposure could be related to ongoing exposure. However, some of the increase in blood lead concentration in adult exposed subjects seemed to be a result of endogenous exposure from increased bone lead stores. The endogenous exposure relation found for men was consistent with reported data, but the relation found for women was significantly lower. Further research is needed to find whether the observed differences are due to sex, or pregnancy and lactation.

Surveillance for emergency events involving hazardous substances--United States, 1990-1992.

PROBLEM/CONDITION: A review of existing reporting systems indicated that not enough information was being collected to determine the public health consequences of emergency events involving hazardous substances. REPORTING PERIOD COVERED: January 1990 through December 1992. DESCRIPTION OF SYSTEM: State health departments in selected states collect and each quarter transmit information about the events, substances released, and the public health consequences of hazardous substance releases (i.e., morbidity, mortality, and evacuations) to the Agency for Toxic Substances and Disease Registry (ATSDR). Five state health departments (Colorado, Iowa, Michigan, New Hampshire, and Wisconsin) began data collection on January 1, 1990. On January 1, 1992, the reporting state health departments included those from Colorado, Iowa, New Hampshire, New York, North Carolina, Oregon, Rhode Island, Washington, and Wisconsin. RESULTS AND INTERPRETATION: During 1990-1992, 3,125 events were reported from participating states to ATSDR's Hazardous Substances Emergency Events Surveillance (HSEES) system. Of these events, 2,391 (77%) were fixed-facility events (i.e., occurred at stationary facilities), and 723 (23%) were transportation related. In 88% of events, a single chemical was released. The most frequently released hazardous substances were volatile organic compounds (18% of the total 4,034 substances released), herbicides (15%), acids (14%), and ammonias (11%). In 467 events (15% of all events), 1,446 persons were injured; 11 persons died as a result of these injuries. Respiratory irritation (37%) and eye irritation (23%) were the most frequently reported health effects. A total of 457 (15%) events resulted in evacuations; of these, 400 (88%) were ordered by an official (e.g., a police officer or firefighter).(ABSTRACT TRUNCATED AT 250 WORDS)

Public health consequences of hazardous substance releases.

Information collected on events and public health consequences can indicate trends in temporal and spatial distribution, chemical releases, and morbidity and mortality of emergency events. This knowledge will be useful in training first responders, planning preparedness for such events, and formulation of guidelines and policies. The impact of such training or policies should reduce both the number of events (primary prevention) and the morbidity and mortality associated with these events (secondary prevention). HSEES is the first comprehensive, state-based surveillance system of hazardous substance releases and public health consequences. Successful implementation of the system requires an active, state-based approach that uses multiple data sources and collects information in a consistent format. Good working relationships between agencies are of paramount importance for obtaining notification about events and information for the lengthy data-collection form. The system is more sensitive in recording hazardous substance releases than any existing single national database, as shown through quality-control evaluations in which HSEES data are compared with events reported to other databases. Consistency in data reporting is further evaluated by case studies sent to states on a regular basis. The five states that participated during the first 2 years of surveillance were not randomly selected. However, with additional states participating in HSEES, the representativeness of surveillance data will improve for making national estimates.

Risk factors for hazardous substance releases that result in injuries and evacuations: data from 9 states.

This study was undertaken to determine risk factors associated with hazardous substance releases (at fixed facilities or during transport) that have public health consequences. Data from nine states with surveillance systems for such releases and their consequences were analyzed. Risk factors were determined for releases resulting in (1) injuries or (2) evacuations. Both outcomes were more likely to occur as a result of facility releases (odds ratio [OR] = 1.89, 95% confidence interval [CI] = 1.44, 2.47, for injuries; OR = 3.29, 95% CI = 2.28, 4.74, for evacuations). Releases of ammonia, chlorine, and acids resulted in injuries and evacuations more frequently than releases of other substances.

Neurotoxicity in young adults 20 years after childhood exposure to lead: the Bunker Hill experience.

OBJECTIVES: An epidemiological study of young adults was conducted to determine whether environmental exposure to lead during childhood was associated with current adverse neurobehavioural effects. METHODS: The exposed group consisted of 281 young adults who had been exposed environmentally to lead as children and the unexposed referent group consisted of 287 age and sex frequency matched subjects. Information on demographics, past and current health, and past exposures to neurotoxicants, and responses to the Swedish Q16 questionnaire were collected by interview. Standard neurobehavioural and neurophysiological tests were administered by computer or trained technicians. K x ray fluorescence was used to estimate tibial bone lead concentrations among the exposed and unexposed groups. Associations were examined between the exposed group and referents and tibial bone lead concentration and the neurobehavioural and neurophysiological outcomes of interest. RESULTS: Among the measures of peripheral nerve function, after controlling for confounders, sural sensory nerve evoked response amplitude, peroneal motor nerve compound motor action potential amplitude, vibrotactile thresholds of fingers and toes, and standing steadiness were significantly associated with exposure group. Among the neurobehavioural tests, hand-eye coordination, simple reaction time latency, trails B latency, symbol digit latency, serial digit, and learning error score were also significantly associated with exposure group after controlling for confounders. Exposed subjects had significantly more neuropsychiatric symptoms than the referents. Associations between tibial bone lead concentration and scores for vocabulary, vibrotactile thresholds of the fingers, and vibrotactile thresholds of the toes approached significance. CONCLUSIONS: Significant adverse central and peripheral neurological effects were found in a group of young adults 20 years after childhood environmental exposure to lead when compared with non-exposed controls. The absence of a significant association between neurological outcomes and tibial bone lead concentration, and the presence of significant associations between neurological outcomes and exposure group may be due to either the magnitude of measurement uncertainty in K x ray films relative to the actual tibial bone lead concentration in these young non-occupationally exposed subjects, or uncontrolled confounding of the exposure group.