Update to WES & Biological Exposure Indices

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Workplace Exposure Standards and Biological Exposure Indices

The 11th Edition of the Workplace Exposure Standards and Biological Exposure Indices Special Guide has now been published on the WorkSafe website here.
Table 1 below shows some of the WES that have been adopted in December 2019, and those for which we intend changing the WES in three years’ time.
Below are some of the changes to 11th Edition of WES & BEI Book

Hydrogen Sulphide

Interim WES-TWA of 5 ppm and STEL of 10 ppm over three years (from date of publication of 2019 WES book) with intention to go to WES-TWA of 1 ppm and STEL of 5 ppm after 3 years.

Lead (Biologicial Exposure Index)

A BEI of 20 g/dL (0.97 mol/L) of whole blood; a suspension (removal) level of 30 g/dL (1.45 mol/L) of whole blood for females not of reproductive capacity, and males; a suspension (removal) level of 10 g/dL (0.48 mol/L) of whole blood for females of reproductive capacity, and those pregnant and/or breastfeeding. 

Silica (crystalline, all forms)

Accept proposed 8-hour WES-TWA 0.05 mg/m3. Review the WES within the next three years. 

Sulphur Dioxide

Accept proposed WES-STEL of 0.25 ppm and remove the WES-TWA 

Wood Dust

Accept proposed 8-hour WES-TWA of 0.5 mg/m3 for hard wood dust.  Retain the current WES-TWA of 2 mg/m3 for soft wood dust with an intention to lower it to 1 mg/m3 in three years.