The Texarkana mercury incident.

In November 1997, 2 teenagers allegedly removed a large amount of metallic mercury from an abandoned sign plant and distributed the material among friends. One teenager developed symptoms and admitted playing with mercury to his physician. His blood mercury was elevated. In February 1998, faculty from the University of Texas Health Center at Tyler conducted an investigation that included in-depth evaluations on 10 patients with urine mercury concentrations up to 100 micrograms/L. Exposure pathways and timelines were reconstructed from records assembled by the Arkansas State Health Department epidemiologist. Mercury contamination was found among teenagers, children, and adults who came in contact with the metal. Biomarkers of exposure documented reduction in mercury concentrations after these persons were removed from their homes and sources of mercury. Neurobehavioral assessment, including assessment of tremor, failed to establish a relationship between mercury exposure and performance.

Exporting DBCP and other banned pesticides: consideration of ethical issues.

Many developed countries permit the export of pesticides that are banned, restricted, or unregistered within their own borders. This practice, which leads to the exposure of agricultural workers in developing countries to high levels of pesticides that are not permitted in the country of manufacture, raises many ethical issues as well as economic, social, political, and public health issues. Worldwide attempts to control export of such pesticides, through the FAO/UNEP Prior Informed Consent program, moves this issue in the right direction. This article explores the current U.S. and international practices, using the specific example of export of DBCP to banana-producing countries. The actions taken by multinational corporations, manufacturers of the pesticides, and public health officials in both the exporting and importing countries are explored, along with the impacts on workers, local economies, governments, and the environment.

Role of biomarkers of exposure in the assessment of health risks.

Biomarkers of exposure can be used as part of an exposure assessment to assess potential health risks when exposure measurements and health effects occur during the same period of time. Exposure assessment is the determination of the concentration of a chemical in an environmental medium coupled with the presence of the human in that environment. A biomarker of exposure gives an assessment of absorbed dose in the worker. A biomarker of effect, often referred to as a biomarker, is used in the assessment of health risk. A biomarker of effect gives an assessment of the effect of a chemical on a physiological process and is an indicator of a possible adverse health effect. For example, biomarkers of exposure give an assessment of a worker's current exposure to solvents and some metals. Biomarkers of exposure for chronic health effects with long latent periods, such as carcinogens, are more problematical. These exposure indicators, however, can be used to help reconstruct past exposures. Selected biomarkers of exposure can also be predictors of adverse health effects. Examples include the use of 2,5-hexanedione and 2-ethoxyacetic acid in urine as indicators of exposure to n-hexane and 2-ethoxyethanol, respectively. These two urinary metabolites are 'active' metabolites responsible for observed neurotoxic and reproductive effects. Biomarkers of exposure are particularly useful for the objective assessment of current systemic exposure to chemicals that are readily absorbed through the skin. Exposure assessments, including the use of biomarkers of exposure, are necessary to postulate a cause of observed adverse health effects seen in epidemiological investigations and to determine the bioavailability of the chemicals present in the workplace.

Interpretation of urine results used to assess chemical exposure with emphasis on creatinine adjustments: a review.

This paper reviews the process of elimination of creatinine (CRE), and the limitations presented when using it to express urine concentrations. This literature review leads to three conclusions: (1) CRE excretion is subject to wide fluctuations due to specific internal and external factors; (2) the use of CRE to correct chemical concentrations in urine will not necessarily improve the correlation to the exposure dose for all chemicals (it may, in fact, worsen the result); and (3) other means of expressing urine concentration may offer greater accuracy towards estimating individually absorbed dose.

Applications of biological monitoring in occupational health practice: practical application of urinary 2-ethoxyacetic acid to assess exposure to 2-ethoxyethyl acetate in large format silk-screening operations.

A practical application of urinary 2-ethoxyacetic acid (EAA) to assess occupational exposure to 2-ethoxyethyl acetate (EGEE-Ac) during a large format silk-screening operation is described. Industrial hygiene air monitoring of employees of a silk-screen shop producing large aircraft interior panel coverings revealed a broad range of exposures to EGEE-Ac. Time weighted exposures averaged 12 ppm (range 2.9-34 ppm) in press operators during production press runs, exceeding the 5 ppm Washington State permissible exposure limit. Employees were instructed to use organic vapor respirators until engineering controls could be developed. Urinary monitoring of EAA was conducted on 30 employees by the company medical department to aid in exposure risk assessment and to assess compliance. Results obtained ranged from 1.1-27 mg EAA/g creatinine which compares favorably with the proposed Biological Exposure Index (BEI) of 100 mg EAA/g creatinine. Results of representative air and biological monitoring, and observations of work practices for different exposure groups indicated that inhalation exposure was the predominant route of exposure. Follow-up testing to assess the efficacy of a newly installed ventilation upgrade is planned.

N,N'-diethyl-m-toluamide (m-DET): analysis of an insect repellent in human urine and serum by high-performance liquid chromatography.

A procedure for monitoring m-DET in human urine and serum is described. m-DET is removed from the urine specimen by partitioning into diethyl ether, but solid-phase extraction is used to remove it from human serum. The urine and serum m-DET values are determined by HPLC with a UV detector. The limit of detection was 0.09 micrograms/mL in urine and 0.09 micrograms/g for serum. The percent of m-DET recovered from human urine spiked between 0.50 and 8.00 micrograms/mL was 90 +/- 5.4%. For human serum spiked between 0.25 and 10.00, the percent recovered was 96 +/- 5.9%. The pooled relative standard deviations (RSD) for spiked matrices were 0.06 for urine and 0.06 for serum.

The biological exposure index: its use in assessing chemical exposures in the workplace.

Human exposure to chemicals in the workplace has traditionally been assessed by determining the concentration of an airborne chemical in the workroom air. More recently, biological monitoring has been used to assess worker uptake of chemicals by all routes of exposure. Both approaches for the assessment of exposure and uptake are complementary. This relationship is examined, along with the advantages and limitations of using biological monitoring. The concept of the biological exposure index (BEI), developed by the American Conference of Governmental Industrial Hygienists (ACGIH), and information on the intended use and interpretation of BEIs are described. Examples are presented on the use of biological monitoring in NIOSH Health Hazard Evaluations (e.g., carboxyhemoglobin in blood to assess exposure to carbon monoxide, urinary metabolites of trichloroethylene to assess exposure to trichloroethanol, and 2-ethoxyacetic acid in urine to assess exposure to 2-ethoxyethanol). The progress of current research studies on the biological monitoring of volunteers exposed to paint spray solvents is presented, along with speculation on the future directions of biological monitoring research.

Body burden profiles of single and mixed solvent exposures.

The dynamics of inhaled solvents have not been studied extensively for exposure conditions involving combinations of chemical agents. An ongoing laboratory study examining psychomotor performance effects on human volunteers exposed to spray paint agents offered an opportunity to gather data on the body burden profiles produced by the inhalation of two solvents alone and in combination. Breath and blood samples were collected from 70 male and female subjects who were randomly assigned to four treatment conditions: chemical placebo, 250 ppm acetone, 200 ppm methyl ethyl ketone, or 125 ppm acetone/100 ppm methyl ethyl ketone. The exposures lasted for four hours. No interaction between the two solvents affecting uptake or elimination was noted. There were no significant differences between the uptake and elimination in males and females. The results are discussed in relation to physiological simulation modeling of the exposure.

Biological exposure index as a complement to the TLV.

The American Conference of Governmental Industrial Hygienists (ACGIH) has recognized the value of biological monitoring for assessing worker exposure to chemicals. The ACGIH has established a Biological Exposure Indices Committee to review literature, prepare documentation analogous to the widely used TLVs, and recommend biological exposure indices (BEIs) for selected workplace chemicals. The BEIs represent an in-depth review of the literature and address such important issues as routes of exposure, absorption, metabolism, uptake, pharmacokinetics, sampling, methods of analysis, interferences (both chemical and metabolic), and interpretation of results. The recommended BEIs represent levels of some biological parameter that would be found in a worker following an 8-hour exposure (at moderate work) to the current TLV. To date, ten documentations and an introduction have been published by the ACGIH. They include toluene, xylene, ethylbenzene, carbon monoxide, styrene, benzene, n-hexane, lead, phenol, and trichloroethylene. Others are in preparation.

Final report of the Color Additive Scientific Review Panel.

The Color Additives Scientific Review Panel considered whether there was information sufficient to perform a carcinogenic risk assessment on the colors D&C Red No. 19 (R-19), D&C Red No. 37 (R-37), D&C Orange No. 17 (O-17), D&C Red No. 9 (R-9), D&C Red No. 8 (R-8) and FD&C Red No. 3 (R-3) and to evaluate the assessments sent to FDA as part of the petitions for use of the colors for drug and external uses by the Cosmetic, Toiletry and Fragrance Association (CTFA). There is a lack of human data concerning the colors for making a human health assessment, so the assessments are based upon the extrapolation of animal data. The risk assessments are determined for exposure to single chemicals. Excluded from consideration are possible effects from exposure to multiple chemicals, such as co-carcinogenesis, promotion, synergism, antagonism, etc. In the light of recent efforts in establishing a consensus in risk assessment, the Panel has determined that the CTFA assessments for R-10, O-17, and R-9 are consistent with present acceptable usages, although it questions some of the assumptions used in the assessments. The Panel identified a number of general assumptions made, and discusses their validity, their impact on total uncertainty, and the potential options to address the gaps in understanding that necessitate the assumption. The Panel also derived revised risk estimates using more "reasonable" assumptions than "worst-case" situations, for 90th percentile and average exposure. For those assumptions that are easily quantifiable, the Panel's estimates are less than an order of magnitude lower than the CTFA risk estimates, indicating that the underestimates and overestimates of the CTFA risk estimates tend to balance each other. The impact of most of the assumptions is not quantifiable. The assessment for R-3 is complicated by the fact that there is no good skin penetrance study for this color. It was assumed that the penetrance is similar to that of another water-soluble xanthene color, R-19. It is expected that the absorption of the color is not likely to exceed that of the smaller molecule, R-19. Therefore, the risk estimates are similar to the CTFA estimates, but with different reasoning. The estimates for R-8 and R-37 are different from the others in that there is a lack of any exposure or toxicological information on these colors.(ABSTRACT TRUNCATED AT 400 WORDS)

Analyses of ethylene glycol monoalkyl ethers and their proposed metabolites in blood and urine.

Glycol ethers are known to produce embryotoxic and teratogenic effects in a variety of animal species. In addition, testicular edema and tubular atrophy have been reported. The health effects of this class of compounds are not known in humans, despite the fact that these solvents are widely used in industry. In order to evaluate potential effects in humans, it is first necessary to estimate exposure in the workplace (environmental monitoring). However, in the case of glycol ethers traditional air monitoring may be ineffective because of the low volatility of these solvents and the possible significant exposure via the skin. Biological monitoring can be used to estimate glycol ether uptake by all routes of exposure. The compounds can be measured in blood or their metabolites quantitated in urine. These procedures are suggested for measuring 2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol in blood. In addition, tentative procedures have been developed to measure the oxidized acidic metabolites, methoxyacetic acid and ethoxyacetic acid in urine as possible indices of exposure. All procedures have detection limits of less than 11 parts per million. These procedures are ready to be validated in workers exposed to these solvents.

Metabolism of nine benzidine-congener-based azo dyes in rats based on gas chromatographic assays of the urine for potentially carcinogenic metabolites.

Metabolism experiments were conducted with rats dosed with nine azo dyes based on dimethyl-, dimethoxy-, or dichlorobenzidine to determine whether the free amine congeners, their monoacetyl or diacetyl metabolites, or alkaline hydrolyzable conjugates were excreted in the urine. After preliminary tests of the dyes, 2-mg doses were administered to each animal and urine samples were collected at intervals up to 96 hours. EC/GC procedures were based on the analysis of heptafluorobutyryl derivatives of the free amine congener moieties or their monoacetyl metabolites. Peak levels of metabolites were excreted either 0-12 or 12-24 hours after administration and, in seven of nine instances, no metabolites persisted in the urine after 48 hours. Minimum detectable levels of all metabolites were 12 ppb or less. All nine dyes were shown to be converted to measurable levels of their benzidine-congener-based metabolites in rats.

Metabolic and health consequences of occupational exposure to polychlorinated biphenyls.

In surveys of three groups of workers occupationally exposed to polychlorinated biphenyls (PCBs) serum PCB concentrations were quantitated as lower chlorinated biphenyls (L-PCBs) and higher chlorinated biphenyls (H-PCBs). Serum L-PCB and H-PCB concentrations were many times greater among workers employed in power capacitor manufacturing than exposed areas. Statistically significant positive correlations of symptoms suggestive of mucous membrane and skin irritation, of systemic malaise, and altered peripheral sensation were noted with increasing concentrations of serum PCB. No clinical abnormalities attributable to exposure to PCB were observed. Serum PCB concentrations were positively and significantly correlated with glutamic-oxalacetic transaminase (SGOT), serum gamma-glutamyl transpeptidase (GGTP), and plasma triglyceride, and inversely correlated with plasma high density lipoprotein-cholesterol. These correlations were present across all study sites. These findings are indicative of PCBs' physiological effect on the liver, whose long-range health significance is unknown. Nevertheless, the consistent positive association of serum PCB with plasma triglyceride and negative association with plasma HDL-cholesterol may have long-term cardiovascular consequences.

Chemical monitoring of urine from workers potentially exposed to benzidine-derived azo dyes.

Benzidine (Bzd) and monoacetylbenzidine (MoAcBzd) were found in the urine of workers exposed to benzidine-based azo dyes. A colorimetric screening method, based on the reaction of extracted free aromatic amines with 2,4,6-trinitrobenzene-sulfonic acid (TNBS), was used with a specific electron-capture gas chromatographic (EC-GC) method. Alkaline hydrolyzable conjugates of Bzd and 2,4-diaminoazobenzene (DiAmAzBz) were found together with free DiAmAzBz and traces of 3,3'-dimethylbenzidine (DiMeBzd) and 3,3'-dimethoxybenzidine (DiMxBzd). The presence of a known human bladder carcinogen (Bzd) and its metabolites in the urine of workers exposed to benzidine-based azo dyes is a cause for concern.

Occupational exposure to synthetic estrogens--the need to establish safety standards.

An environmental survey of a plant formulating oral contraceptives demonstrated considerable variation in possible synthetic estrogen exposure to the plant personnel. Clinical epidemiological studies showed evidence of increased absorption of estrogens in some employees at the plant. In view of the company's considerable efforts to suppress dust from work areas, new approaches to containment may be necessary with biologically active dusts--including the establishment of a dust standard.