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We have identified 71 chlorophenate-exposed sawmill workers as part of a group undergoing an extensive health and environmental evaluation in a pulp mill. We have compared this group with a group (351) with no physical proximity to the area in which chlorophenates were used. We demonstrated a gradient of exposure from 230 ppb in urine and 919 ppb in serum for those directly handling the contaminated wood, to 139 ppb in urine and 354 ppb in serum for those working in the area but not in manual contact as compared with serum levels of 84 ppb in the unexposed group. We noted that the bulk chemical was primarily in the tetrachloro-form but the serum levels contained more pentachlorophenate. The urine proportions were intermediate, approximating the bulk chemical proportions at the lower levels of exposure. We did not find an excess prevalence of respiratory symptoms or spirometric abnormalities which could be explained by the chlorophenate exposure.

The ability to detect the characteristic "chocolate" brown color of methemoglobin containing blood was tested in a double blind study. We prepared three concentrations of methemoglobin by adding sodium nitrite to 1-2 ml of venous, heparinized blood that was "arterialized" by mixing with room air in vacutainer tubes. House officers (HO) were asked, in a standardized protocol, to make observations ("chocolate", "abnormal" or "normal") about the methemoglobin blood alone (first in Vacutainer, and then on filter paper), and then in comparison with control blood, again in Vacutainer, then filter paper. Each HO assessed only one methemoglobin concentration. Three methemoglobin blood samples were studied with 12-14%, 26-35% and 68% methemoglobin concentrations respectively. We found that the ability to detect visually an abnormal appearance of methemoglobin was significantly improved when the test sample was compared to control blood. The descriptive term "darker than normal" was much more commonly used than "chocolate" to describe the methemoglobin blood.