Asri, Amiratul Aifa Mohamad
(2020)
Respiratory effects of aflatoxin b1 and risk of workplace to home exposure among selected rice millers in Malaysia.
Masters thesis, Universiti Sains Malaysia.
Abstract
Rice milling process produces a huge amount of dust which may contain fungal
toxins due to improper handling and storage at high humidity levels. Aflatoxin B1
(AFB1) is the most potent among the aflatoxins and carcinogenic to humans when
ingested or inhaled that might cause hepatocellular cancer or lung cancer. This study
aims to assess the exposure of AFB1 and its respiratory effects among selected rice
millers in Malaysia. Area and personal dust exposure were evaluated using a sampling
train consist of a glass microfibre filter, IOM sampler and GilAir Plus Personal Air
Sampling Pump. The pump was worn for eight working hours, attached to the workers’
belt. Lung function test was performed pre and post-shift. The palms of both hands of
the workers were swabbed with sterile cotton pads wetted with Phosphate Buffered
Saline Tween-20 solution (PBST), pre and post-shift. Home dust sampling was done
by vacuuming the living room using a DUSTREAM collector containing mesh nylon
filter attached to a vacuum cleaner. The results were then compared with the control
group involving USM administration workers. Questionnaires were given to collect
information on sociodemographic data, occupational details, personal protection
equipment (PPE) compliance, workplace practices, respiratory symptoms and factors
that lead to take-home exposure to AFB1. Altogether, there were 115 subjects
participated in the study, 77.5% of them are Malay. AFB1 was detected in 14.1% (n =
10) of personal airborne dust samples (median: 0.16, IQR: 0.14-0.90). Post-shift hand
swab was positive with AFB1 in two rice millers 13.0% (n = 2) (median: 0.24 ng/ml,
IQR: 0.24-0.27 ng/ml). However, AFB1 was non-detected on hand swabs among
office workers (<LOQ: 0.24 ng/ml). There was no significant difference was found in
post-shift lung function between rice millers and controls (FVC: p = 0.911, FEV1: p =
0.637, FEV1/FVC: p = 0.385, PEF: p = 0.160) after controlled for gender and smoking
as confounders. The AFB1 home dust level among rice millers was 0.18 ng/kg (IQR:
0.08 – 8.32). There was no significant difference in AFB1 levels in home dust between
both groups. To conclude, detected AFB1 at rice mills (airborne filter and hand swabs)
were lower than the permissible limit (30 ng/m3). Consequently, there is no significant
correlation between workplace and home AFB1 levels. Thus, the presence of AFB1 at
home could be influenced by environmental factors such as human activities at home.
Cumulative effects may pose risks over the years so proper control measures such as
hygiene practices at work and preventing take-home exposure are highly
recommended to reduce the levels of AFB1 among the workers and their family
members.
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