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Aflatoxin (AF), a highly potent hepatocarcinogen, is strongly implicated in the pathogenesis of human hepatocellular carcinoma (HCC). In this study, our aim was to determine if this carcinogen is associated with cases of HCC in Singapore. Blood levels of the naturally-occurring AFs--B1, B2, G1 and G2--were assayed in 56 cases of HCC. AF was detected in only 2/56 (3.6%) cases of HCC, one each of AF-B1 and AF-G1. In contrast, in a similar survey done in Singapore on normal subjects, AF was positive in 64/423 (15.1%) cases. The low frequency of AF detection in our patients suggests that HCC in Singapore is not associated with significant chronic exposure to AF.

The toxicology laboratory provides a whole range of forensic toxicology services to the doctors, pathologists, law enforcement agencies and the public. This paper, anchored in one hundred and ten years of history, traces the practice and development of this laboratory to the present day of offering services in blood for alcohol determinations, antemortem biological fluids (gastric aspirate, blood, etc.) and postmortem biological fluids and tissues (liver, kidney, etc.) for drugs and poisons screen. This paper spells out in detail the nature of specimens required, the analytical techniques used, the toxins looked for and the medico-legal implications of our analytical findings. A number of recent cases of interest are presented.

Between 1987 and 1989 there were approximately 5,000 cases of fatal and injury-sustained road traffic accidents, of which 2.3-3.0% were alcohol related (blood alcohol levels greater than the legal limit of 80 mg% ethanol). The offenders of alcohol-related accidents are mostly Chinese (> 79%), male (> 98%), and more often 30-40 years old. The majority of the alcohol-related accidents (> 74%) took place between 8 P.M. and 4 A.M. in fine weather and light traffic. Rear-end, head-on, and side-on collisions comprised > 60% of all the alcohol-related accidents, and losing control of vehicles approximately 30%. Drunken driving cases for the same period that were not accidents showed a number of characteristics similar to those for accidents. In Singapore, motorcycle riders and pedestrians are more prone to road fatality than other road-user groups. International comparisons of road fatalities per 100,000 population gave Singapore one of the lowest accident rates (8.1-8.4) as compared with countries such as Australia, the United Kingdom, the United States, New Zealand, Canada, and Japan.

In the early eighties, in response to increasing self-poisoning incidents by pharmaceuticals in Singapore, a comprehensive wide-sweep screen for these drugs in clinical gastric aspirates was devised and implemented by us. The toxicological screen which involved quadruplicate extractions, two in acidic conditions and the other two in alkaline conditions, required the following analyses to be carried out: UV on the acidic fraction, TLC on the basic fraction and mega-bore capillary GC/NPD (nitrogen phosphorus detector) on the combined fraction. The combined fraction if necessary was subjected to GC/MS analysis. Our screen satisfied the need to confirm the analytical outcome of one method by another. Combining the acidic and basic fractions for a single GC analysis saves on instrument time and manpower. All coma and emergency cases were required to undergo GC/MS analysis to prove the identity of toxic agents beyond reasonable doubt. Quality control procedures were instituted at key steps to ensure quality of analytical outcome.

A study on past toxicological activities in Singapore enabled us to capture the trends of poisons abused in this country over the last 108 years. Until the early sixties, corrosive alkali and acids, alcohol (poisoning cases), inorganic chemicals, heavy metals and plant alkaloids were the mainstay of poisons principally used. The seventies and eighties saw a swing towards pharmaceuticals. The 1988-89 data gave alcohol (poisoning cases), pharmaceuticals, household items such as detergents, hypochlorite and antiseptic, carbon monoxide, paraquat, malathion, organic solvents (toluene and xylenes) and narcotics as the mainstay of poisons encountered. The last two classes of poisons reflect the continuing problems of glue sniffing and narcotics abuse facing Singapore.

In the period 1987 to 1989 there were about 5,000 cases of fatal and injury-sustained road traffic accidents, of which 2.3 to 3.0% were alcohol-related (Blood alcohol levels greater than the legal limit of 80 mg % ethanol). The offenders of alcohol-related accidents are mostly Chinese (greater than 79%), predominantly of the male gender (greater than 98%), and more often than not in the 30 to 40 age-range. The majority of the alcohol-related accidents took place between 8 p.m. to 4 a.m. (greater than 74%) under fine weather and light traffic. Rear-end, head-on and side-on collisions comprised over 60% of all the alcohol-related accidents and losing control of vehicles about 30%. Drunken driving non-accident cases for the same period showed a number of characteristics similar to those for alcohol-related accident cases. In Singapore motorcycle riders and pedestrians are more prone to road fatality than other road-user groups. International comparisons of road fatalities per 100,000 population gave Singapore one of the lowest accident rates (8.1 to 8.4) as compared to countries such as Australia, the United Kingdom, the United States, New Zealand, Canada and Japan.

Urinary borates calculated as boric acid were found to span 0 to 54 microgramme per ml urine for both Singaporean adults (population size: 507) and children (population size: 162). The normal dietary boron intake could account for the urinary boric acid levels observed. Of the hundred and fifty-three children who suffered from gastroenteritis in Singapore over the period from Jan to May 1989, two were found to have urinary boric acid exceeding 54 micrograms per ml urine. One of them was said to have consumed fish balls, bean curds and noodles prior to the onset of illness. These food items were among those likely to have added borates. Unfortunately, the dietary intake prior to the onset of illness of the other child was not recorded. Of the hundred and twelve adults affected by gastroenteritis in Dec 1988 in the Tiong Bahru area, one was found to have boric acid level of 117 micrograms per ml urine, indicative of added borates in the diet. The present study showed that borates related gastroenteritis incidents in Singapore over the time-period of our study at least, were few and far in between. With the on-going surveillance for the presence of added borates in both locally manufactured and imported food and the continued tight control over the importation and sale of borates, future incidents are likely to be minimal.