Evaluation of data and recommendation on measurement technique and sampling protocol for determining concentrations of engineered and incidental nanoparticles

Introduction
The National Institute for Occupational Health (NIOH) of the National Health Laboratory Service (NHLS) support the South African public health service. NIOH is conducting an OECD-approved study on human exposure assessment of engineered gold nanoparticles in research laboratories. A similar study will also be done in laboratories synthesising carbon-based engineered nanotubes and in a power generating utility, producing carbon-based incidental nanoparticles.

Aim is to generate and evaluate relevant data to establish appropriate assessment and control methods and identify and prioritise exposure levels; to suggest control measures in line with observed exposures scenarios; to develop a simple risk assessment tool/checklist to assist managers in the process of health hazard identification and risk prioritisation.

Methods
This is a descriptive, qualitative study with 4 phases: (1) Hazard Identification – based on available scientific literature, field observations and interviews, identifying potential exposure situations during the processes; (2) Exposure risk quantification through occupational hygiene field measurements at ‘actual’ point/s of emission and at ‘background’ positions (3) The physico-chemical characterisation of particle concentrations captured on filtres of less than 1 µm pore size, for mass, number, size distribution and surface area where possible with relationship to toxicity outcomes postulated (4) Identification and evaluation of control measures for their efficacy for each exposure scenario (5) development of a pre-exposure risk-assessment checklist for use by managers to evaluate possible exposures during the operation of processes.

Results
Generated data will be used to evaluate exposure risks to engineered gold nanoparticles, carbon nanotubes and incidental nanoparticles. Appropriate control measures to manage workers’ exposures will be identified and evaluated.

Discussion
Although this study is conducted in research laboratories and a real-life workplace process, assessment techniques and appropriate control measures identified that will be established and the risk assessment tool that will be developed could be applied/adapted for any standard setting measure.