Is “No-Threshold” a “Non-Concept”?

A controversy prominent in scientific literature that has carried over to newspapers, magazines, and popular books is having serious social and political expressions today: “Is there, or is there not, a threshold below which exposure to a carcinogen will not induce cancer?” The distinction between establishing the existence of this threshold (which is a theoretical question) and its value (which is an experimental one) gets lost in the scientific arguments. Establishing the existence of this threshold has now become a philosophical question (and an emotional one). In this paper I qualitatively outline theoretical reasons why a threshold must exist, discuss experiments which measure thresholds on two chemicals, and describe and apply a statistical method for estimating the threshold value from exposure-response data.     

Threshold estimation from the linear dose-response model: Method and radiation data

The linear dose-response model is considered a conservative, nonthreshold relationship. This is based on a confusion between the sufficient condition (that is, zero slope at zero dose) and the necessary condition (that is, response distinguishable from zero). Once the threshold is properly defined, it is shown that the linear model predicts thresholds for radiation data in good agreement with experimental results.     

CRITIQUE—Consumer product safety: Risk assessment of exposure to asbestos emissions from hand-held hair dryers

The paper by Dr. William Hallenbeck of the University of Illinois on pp. 23–32 of this issue ofEnvironmental Management contains an estimate of the risk of respiratory cancer resulting from exposure to asbestos fibers emitted from asbestos-containing hairdryers. The study, which is described as a worst case analysis, concludes that the use of these hairdryers would result in a maximum of 0.15 deaths from respiratory cancer per year in the United States, based on a median case estimate of asbestos fiber emission from hair-dryers. This estimate of risk was developed using data from one epidemiologic study.In this critique, we suggest that the use of other epidemiologic studies and the inclusion of other minor, reasonable changes to the basic assumptions made by Hallenbeck could significantly change the estimate in the direction of greater risk. Indeed, the use of other epidemiologic studies in the risk estimate results in an increase in the predicted risk of up to 3 orders of magnitude. Inclusion of changes both in the epidemiologic study used and in certain model assumptions results in an increased risk prediction of over 4 orders of magnitude in the extreme.Since there is no definitive basis on which to include or exclude certain assumptions or relevant studies, the risk estimate at best must be represented as a range of values. Such a range demonstrates the inherent uncertainties associated with estimating the risk to humans from known carcinogens. The size of the range developed in this analysis may actually be underestimated since no attempt has been made to evaluate the uncertainty associated with the choice of the dose-response model.The material found within this paper contains the views of the authors who are employees of the Consumer Product Safety Commission and does not necessarily reflect official opinions or policies of the U.S. Consumer Product Safety Commission.This paper was prepared in the course of the official duties of the authors as employees of the U.S. Consumer Product Safety Commission. It is in the public domain and may be freely copied and reproduced.     

两波长定域同步荧光光谱法快速测定苯并(a)芘的研究

本文提出了快速测定环境样品中强致癌物BaP的两波长定域同步荧光光谱法(SFDW),样品经有机溶剂超声提取后,可以不经过预分离而直接用于测定,该方法操作简单、快速、灵敏,分析一个样品的时间由原来的1小时缩短为几分钟。其检测限为10~(-10)g,定量的线性范围至少可达三个数量级,该方法直接检测BaP的结果和样品经过分离后,采用高效液相色谱法(HPLC)测定的结果相近,其相对误差小于±20％,易于实现仪器化。     

Analysis of carcinogenic and mutagenic aromatic amines: An overview

The aromatic amines represent a category of considerable importance in terms of their broad industrial utilization per se as well as intermediates in the manufacture, of a wide variety of dyes which have been broadly used in textile, leather, plastic and paper products as well as in permanent and semi‐permanent coloring products. The exposure to these agents, a number of which are carcinogenic and/or mutagenic, can occur primarily via skin contact and inhalation and covers the spectrum of occupational, consumer and the general public. This overview will principally highlight a number of the recently applied methodologies (including GLC, HPLC, and SPF) for the analyses of benzidines, naphthylamines, aminobiphenyls, methylene bis(2‐chloro‐aniline); 2,4‐diaminotoluene and 2,4‐diaminoanisole with a focus on their determination in environmental and occupational samples.