I was watching a TV programme the other evening, whiling away my lockdown hours, when I came across a programme of unknown vintage about food in the UK. Part of the programme was about ‘chlorine washed chicken’, so it can’t be that old. This was quite interesting as the scientist (sorry, didn’t get the name) showed Salmonella cells surviving a chlorine wash of chicken, although somehow not commenting on the wall-to-wall Salmonella on the water washed plate. It was claimed that a chlorine wash papers over the cracks of poor hygiene/husbandry up to the point of slaughter and processing. I have discussed ‘chlorine washing’ elsewhere.
I was somewhat amazed to hear it opined that the US suffered ten-times worse foodborne disease that the UK does, presumably to underscore how well foodborne disease is under control when food is subject to EU regulations (bearing in mind that we do not belong to the EU any more). Is this true? I honestly didn’t know as I have previously compared UK and US data with those from New Zealand, not against each other. I thought that, for campylobacteriosis at least, the US was running at around 20 and the UK 100 cases per 100,000. The US was, according to my recollection, five times better that the UK. So, I needed to check up on these claims.
To keep things focused I’ll only consider campylobacteriosis and salmonellosis since they are diseases well established as being linked to the consumption and/or handling of raw poultry. The information is presented in the table below:
|Disease||UK rate1 (/100,000) 2018||US rate2 (/100,000) 2019|
1 European Food Safety Authority and European Centre for Disease Prevention and Control (EFSA and ECDC) (2019) The European Union One Health 2018 Zoonoses Report. EFSA Journal 2019;17(12):5926.
2 D.M. Tack; L. Ray; P.M. Griffin; P.R. Cieslak; J. Dunn; T. Rissman; R. Jervis; S. Lathrop; A. Muse; M. Duwell; K. Smith; M. Tobin-D’Angelo; D.J. Vugia; J. Zablotsky Kufel; B.J. Wolpert; R. Tauxe; D.C. Payne (2020) Preliminary Incidence and Trends of Infections with Pathogens Transmitted Commonly Through Food — Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2016–2019. Morbidity and Mortality Weekly Report. 69 (17)
In a very crude analysis, the data for salmonellosis are quite similar, while the UK has 4-5 the rate of campylobacteriosis as the US. I’ve always been suspicious of the US data as they are very low. For example, the overall rate for the EU is around 64 cases per 100,000 and the rate for the Czech Republic is 215.8/100,000. However, there is nothing here to say that the US is ten-times worse than the UK. It also agrees with my memory of past projects, which is something of a relief. The data might even suggest that the UK should start chlorine washing chicken as soon as possible to reduce campylobacteriosis by 80%, but that would be mis-using the data quite badly.
There are some caveats. Firstly, the data are not for the same year, but they are for the most recent year where data are available. Secondly, the data are collected in different ways, for example the US data are for 10 sentinel sites while the UK data are not and the methods used to collect samples and test them will be different (the difficulties comparing data between countries have come to the fore during the covid-19 pandemic). I’m sure there are more, but we are not comparing in exact detail, the idea is to get an estimate of the magnitude in each country, the ‘ten times’ factor given by the scientist on the box.
It is also acknowledged that this information, which is based about detections in human cases, is an underestimate. For example in 2011 Scanlan (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375761/pdf/09-1101p1_finalR.pdf) examined data for the US and estimated that there were around 25 times more cases of domestically-acquired salmonellosis than were laboratory conformed, once under reporting and under diagnosis was taken into account. Different ways of attempting to quantify this under ascertainment make comparisons even more difficult.
So, I don’t know where the data supporting the “ten-times” claim comes from (well, it may be here: https://fullfact.org/health/food-poisoning-US-UK/) and that comparison is made on estimated cases rather that confirmed cases, but in a way it’s not the point. With respect to the whole point of making the comparison in the first place, It isn’t a case of either rearing broilers in a hygienic and high welfare way OR chlorine washing of carcasses. You can have both.