Trends in occupational asbestos exposure and asbestos consumption over recent decades in Korea

Our plain-English summary of Trends in occupational asbestos exposure and asbestos consumption over recent decades in Korea, by D. Park, S. Choi, K. Ryu, et al (International Journal of Occupational and Environmental Health, 2008).

The study

• Authors: D. Park, S. Choi, K. Ryu, J. Park, N. Paik
• Journal: International Journal of Occupational and Environmental Health
• Published: 2008;14(1):18-24
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In Korea, national statistics for asbestos exposure levels covering various asbestos industries and associated with specific years have never been published. The authors analyzed 2,089 asbestos exposure data sets compiled from 1995 through 2006. Exposure levels were characterized according to type of asbestos industry and year. Asbestos exposure levels have decreased over time, dropping sharply from 0.92 fibers/cc (f/cc) in 1996 to 0.60 f/cc in 1997, to 0.19 f/cc in 1998, and to 0.06 f/cc in 1999, possibly in part because of enforcement of 1997 legislation banning the use of amosite and crocidolite. In particular, a substantial reduction in asbestos exposure levels was most evident among primary industries handling raw asbestos directly. A similar relationship was found between a significant decline in asbestos consumption volume and the timing of regulation enforcement.

In plain English

The authors analyzed 2,089 asbestos air measurements taken in the breathing zones of workers in Korea from 1995 through 2006, along with national asbestos import data. Fibers were counted by phase-contrast microscopy. The yearly average exposure fell from 0.92 fibers per cubic centimeter (f/cc) in 1996 to 0.60 in 1997, 0.19 in 1998 and 0.06 in 1999. Levels for 1995 to 1997 (average 0.58 f/cc, 739 samples) were significantly higher than in the three later periods, which did not differ from each other. Industries handling raw asbestos or making asbestos-containing materials averaged 0.31 f/cc. That was significantly higher than industries using such materials (0.05 f/cc), and only the first group showed a significant decline over time. Raw asbestos consumption fell from 77,145 tons in 1996 to 44,985 tons in 1997. That was the year amosite and crocidolite were banned and also the year of an economic crisis. Imports of asbestos-containing materials later rose. The authors concluded that declines in exposure and consumption corresponded with the timing of regulation enforcement. They noted missing job information and unbalanced samples across industries and years.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective analysis of workplace asbestos exposure measurements, combined with a review of national asbestos consumption figures, legislation and earlier Korean exposure studies
• Who was studied: 2,089 personal breathing-zone air samples from 38 types of asbestos industries in Korea, analyzed by Seoul National University, 1995 to 2006. There were 1,555 samples from primary industries (handling raw asbestos or manufacturing asbestos-containing materials) and 534 from secondary industries (end users of asbestos-containing materials, or maintenance work). Area, indoor and outdoor air samples were excluded.
• Exposure: Airborne asbestos fibers measured in workplace air and counted by phase-contrast microscopy (NIOSH 7400 method, 'A' counting rules). The results are given in fibers per cubic centimeter (f/cc) and are not broken down by fiber type. The study period spans the May 1997 ban on crocidolite and amosite and the June 2003 ban on anthophyllite, actinolite and tremolite. Chrysotile remained in use.
• Main results:
  • Across all samples, average yearly exposure fell from 0.92 f/cc in 1996 to 0.60 f/cc in 1997, 0.19 f/cc in 1998 and 0.06 f/cc in 1999.
  • Yearly average levels before 1999 were above the current Korean occupational exposure limit of 0.1 f/cc.
  • By time period (Table 1), mean exposure was 0.58 f/cc in 1995 to 1997 (739 samples), 0.09 f/cc in 1998 to 2000 (451 samples), 0.05 f/cc in 2001 to 2003 (616 samples) and 0.03 f/cc in 2004 to 2006 (283 samples). The earliest period was significantly higher than the other three (P less than 0.05), and the later three periods did not differ statistically from one another.
  • Primary asbestos industries averaged 0.31 f/cc (1,555 samples). Secondary industries averaged 0.05 f/cc (534 samples, Table 1). The difference was statistically significant (p less than 0.001).
  • 25% of the 1,555 primary-industry samples exceeded the exposure limit of 0.1 f/cc, compared with 38 (7%) of the 534 secondary-industry samples.
  • In the primary industry group, exposure in 1995 to 1997 differed significantly from the three later periods (p less than 0.0001). In the secondary industry group, there was no significant difference among the four periods (p = 0.129).
  • From 2000 onward, average exposure in secondary industries was higher than in primary industries. For example, in Table 3 the 2001 to 2003 averages were 0.09 f/cc for secondary and 0.04 f/cc for primary industries.
  • The exposure limit was lowered to 0.1 f/cc, as a regulation from 2003. Exposure after 2003 (0.05 f/cc) was not statistically different from the 1999 to 2002 average (0.03 f/cc) (P greater than 0.05).
  • Raw asbestos consumption fell from 77,145 tons in 1996 to 44,985 tons in 1997, the year regulations banning amosite and crocidolite were enacted.
  • An economic crisis occurred in Korea in the same year, 1997, as the amosite and crocidolite ban.
  • Imports of asbestos-containing materials, including cement and fiber products, rose from 9,116 tons in 1996 to 47,967 tons in 2005.
  • In a statistical model of log-transformed concentrations, both time period and industry group were significantly associated with exposure levels (adjusted R2 = 0.245; P less than 0.001).
• The authors' conclusion: The authors concluded that time period and type of asbestos industry were significantly related to exposure levels. They found the reduction most evident in primary industries, and that declines in both exposure levels and consumption corresponded with the timing of regulation enforcement.
• Limitations the authors state:
  • The samples were unbalanced across industries and years.
  • There was no information on the job, operation or task sampled.
  • Consumption and exposure data were not available by asbestos type, so the authors could not check whether the amphibole ban led to increased chrysotile use or exposure.
  • There were no data for the asbestos cement industry, and the construction industry was not included.
  • There were no data from before 1995, so the effect of the first exposure limit set in 1986 could not be examined.
  • The authors stated their results would not be of much value for industry-specific cohort studies.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Amosite, Crocidolite.

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