Cancer risk for meat workers
A study of over 6600 meat industry workers around New Zealand
has found a significantly high rate of cancers, particularly
cancer, which may be caused by exposure to cancer causing agents
carried by animals.
The study, by Dr Dave McLean, Centre for Public Health Research,
followed the health status of 6647 people who work or have worked
in the meat processing industry from three plants, in the North
and South Islands. International research indicates there is an
increased risk of cancers of the lung and larynx, and of leukaemia
and lymphoma, among butchers and slaughterhouse workers. The aim
of this project was to see whether the same was true for New Zealand
and to identify the exposures associated with any increased risks.
Dr McLean says the study found that the rate of lung cancer in
the group was signficantly higher than in the general population.
He says while it is possible that smoking and the ethnicity of
the workers had an impact on these findings, it is highly unlikely
that either factor is sufficient to account for more than a small
part of the excess observed.
There are two key findings that are of considerable interest. The
first is that there is an excess of lung cancer, for which there
is a strong dose-response relationship based on how long people
had worked in certain jobs. Lung cancer was most strongly associated
with exposures to biological material in animal urine, faeces or
blood – we don’t know what the cause is but one possibility
is that they are exposed to a biological element, caused by something
like a bacteria, virus or fungi, which is carried by the animals.
The second finding is that despite small numbers there is evidence
of an association of cancers of the lymphohaematopoietic system
with how long people had worked in meat processing and plant services.
This was particularly associated with exposure to animal faeces.
This effect appears to exist for non-Hodgkin’s lymphoma,
and possibly also for leukaemia.”
Dr McLean says that while there has been very little research into
the types of exposures that occur in the meat industry, potentially
hazardous exposures are primarily biological, including bacterial
and viral infectious agents as well as non-infectious bioaerosols.
There is also a limited range of potential exposures from chemicals
either used in the process or in the maintenance of plant and equipment,
or encountered as residues of animal remedies or pesticides used
Dr McLean emphasises that there is no evidence to implicate the
meat processed in the plants, or indicate any risk to consumers
“Evidence would appear to suggest that the risk is associated
somehow with the handling of live animals and the slaughter process
and the high exposures to that proces, and that it disappears completely
in those jobs that involve the further handling of meat, such as
the meat cutters or retail butchers. But further research is required
before we could positively identify the causes.”
He says the findings could have significance for public health
policy making because of the number of people employed in the meat
processing industry in New Zealand. However, further research is
required to identify the specific agents responsible, so preventive
measures can be developed.
The study found that mortality from all causes was higher than
expected based on the general population (227 deaths compared with
204 expected), and from all cancers (69 deaths compared with 61
expected). Among the cancers, significant excess mortality was
observed for lung cancer (23 deaths compared with 13 expected).
Of the 6647 people studied the majority had been employed on the
slaughter board (44 percent) or in meat cutting (28 percent), with
a further 10 percent employed in departments associated with the
processing of edible and inedible offal and meat wastes.
Dr McLean worked with Soo Cheng and Professor Neil Pearce, from
the Public Health Research Centre, Andrea ‘t Mannetje, from
the International Agency for Research on Cancer (a branch of WHO)
and Alistair Woodward, Wellington School of Medicine, on the project
which was funded by the Health Research Council.