JPH085689Y2 - Inhalation toxicity test equipment - Google Patents

Description

[Detailed description of the device]

[0001]

This invention relates to a device for conducting an inhalation toxicity test for agricultural chemicals, pharmaceuticals, etc. on small animals such as rats.

[0002]

2. Description of the Related Art Generally, an inhalation toxicity test is carried out by using a mist prepared by dispersing a liquid test substance such as an agricultural chemical in a gas such as air in a mist state or a dust prepared by dispersing a powder of a solid test substance in a gas. It is used for inhalation in small animals such as rats, and the toxicity of the test substance is evaluated by the biological damage caused by the inhalation. A typical inhalation toxicity test is an acute inhalation toxicity test. In this acute inhalation toxicity test, the toxicity of the test substance is usually evaluated by the concentration at which half of the test animals die when exposed for a certain period of time (that is, the half-lethal concentration LC ₅₀ ).

The inhalation toxicity test method includes a whole body exposure method in which the whole body of a small animal such as a rat is exposed to an atmosphere containing a test substance, and a head exposure method in which only the head or nose is exposed. In the systemic exposure method, the test substance is dermally administered in addition to inhalation by the respiratory system.
The latter head exposure method is preferable to correctly evaluate toxicity by inhalation only.

As shown in FIG. 5, a conventional inhalation toxicity test apparatus for head exposure has a chamber around a vertical inhalation box body 1 having a hollow cylindrical shape, as shown in FIG. A plurality of openings 2 for exposing the head or nose of the rat are formed at intervals in the circumferential direction, and holders 4 for holding a test animal 3 such as a rat are attached to these openings 2 respectively. A supply device for supplying a test substance such as mist to the upper end portion 1A of the inhalation box body 1, for example, a spray nozzle 5 for spraying a liquid test substance to generate a mist is provided. It is widely known that the gas containing the test substance is sent from the upper side to the lower side in the suction box body 1.

On the other hand, the inventors of the present invention have found that, among various test substances, as an inhalation toxicity test device using a mist in which a liquid test substance is dispersed in a gas in a mist state, a certain particle size excluding unexpected coarse particles is excluded. An inhalation toxicity test device capable of inhaling a mist having a distribution into an animal under test has already been proposed in JP-B-57-45574.

FIG. 6 shows an inhalation box (chamber) of the above proposed inhalation toxicity test apparatus.

In FIG. 6, the suction box body 10 which is a main component of the suction box 90 is made to have a hollow cylindrical shape as a whole, and its upper end portion is a conical surface 11. A mist discharge port 13 communicating with the hollow chamber 12 in the suction box body 10 is formed at the top of the suction box body 10.

Further, on the peripheral wall of the suction box body 10,
The openings 2, 2'to which the holder 4 for holding the test animal 3 such as a rat is attached, that is, the openings 2, 2'for exposing the head of the test animal 3 are circumferentially spaced. Moreover, it is formed in two steps, upper and lower. A supply chamber 1 provided with a test liquid mist supply device, for example, a spray nozzle 14 for generating the test liquid mist, at the lower end of the suction box body 10.
5 is formed in a state partitioned with respect to the hollow chamber 12 in the suction box body 10. That is, the atomizing nozzle 14 is attached upward in the center of the bottom of the supply chamber 15, and a small hole-shaped ejection port 16 is vertically formed at the top of the supply chamber 15. .

Further, in the hollow chamber 12 of the main body 10 of the suction box, the hollow chamber 12 is located directly above the jet port 16.
A disc-shaped collision plate 17 having a diameter smaller than the inner diameter of the is arranged horizontally. The collision plate 17 is arranged at a small distance upward with respect to the upper opening end of the ejection port 16 and has a plurality of support arms protruding inward from the inner peripheral wall of the suction box body 10. The collision plate 17 is mounted and supported on the tip end of the collision plate 18, so that the collision plate 17 is substantially open at its periphery. On the collision plate 17, a hollow space body 19 having a shape substantially similar to the suction box body 10 and smaller than the suction box body 10 is placed. Therefore, in the hollow chamber 12 inside the suction box body 10, the central portion of the space above the collision plate 17 is occupied by the space body 19.

In the inhalation toxicity test apparatus for mist as described above, if compressed air and a test liquid are supplied to the atomizing nozzle 14, the supplying chamber 1 goes upward from the nozzle 14.
5, the test liquid mist is sprayed, the test liquid mist rises in the supply chamber 15 and is converged at the ejection port 16, and the accelerated mist passes through the ejection port 16 and moves upward from the ejection port 16 at high speed. And it collides with the collision plate 17. Therefore, the test liquid mist is classified by the inertial collision with the collision plate 17. That is, the coarse particles in the mist ejected from the ejection port 16 collide with the collision plate 17 to be adhered and aggregated to the collision plate 17, and become droplets and fall from the collision plate 17 under its own weight. On the other hand, mist particles of a certain size or smaller in the mist ejected from the ejection port 16 pass from the lower surface side of the collision plate 17 to the periphery thereof and occupy the inner peripheral surface of the suction box body 10 in the hollow chamber 12. Ascends in the space between the body 19 and reaches the openings 2, 2'and is inhaled by the animal 3 to be tested,
Further, the mist which has not been inhaled by the animal 3 to be tested is discharged from the mist discharge port 13 to the outside of the apparatus by an appropriate exhaust means.

Here, even in the mist composed of the relatively fine particles classified by the inertial collision with the collision plate 17 as described above, the particles agglomerate due to the mutual collision of the particles up to the openings 2, 2 '. Coarse particles may be generated, and the coarse particles may be mixed in the collision plate 17 due to re-scattering. However, since the mist must rise from the collision plate 17 to the openings 2 and 2 ', coarse particles generated by agglomeration and the like settle according to Stokes' settling law, and as a result, the openings are actually formed. The particles reaching 2,2 'are limited to those having a particle size of a certain size or less. Therefore, in the above-mentioned device, the classification effect due to the inertial collision and the sedimentation effect due to Stokes' law are combined, and the inhalation of coarse particles into the test animal is extremely effectively prevented. and again,
By selecting the diameter of the ejection port 16 and the flow rate of the mist ejected from the ejection port 16, the maximum particle size of the mist to be inhaled by the test animal can be set to a desired value in advance.

By the way, in both the head exposure type inhalation toxicity test apparatus as shown in FIG. 5 and FIG. 6 or the whole body exposure type inhalation toxicity test apparatus not shown, the hollow chamber ( That is, the space where dust or mist is flowed and at least a part of the animal under test is exposed must be maintained at a slight negative pressure with respect to the external pressure. In other words, since the mist and dust used in the inhalation toxicity test contain toxic test substances, it is in charge of the test that the mist and dust leak from the inhalation box to the outside and pollute the surrounding atmosphere. It is absolutely necessary to avoid health and environmental problems of personnel, and therefore during testing (during mist or dust supply)
Therefore, it is necessary to maintain a slight negative pressure in the hollow chamber of the suction box so that mist and dust do not leak from the suction box to the outside.

Therefore, as a whole system in the conventional inhalation toxicity test apparatus, a system as shown in FIG. 7 or 8 is used.

In the system shown in FIG. 7, air is taken in from the outside by a feeding means 51 such as a pump or a compressor through a filter 50, and the air is taken in as a mist or dust together with a test substance, for example, a chemical solution 52, in a suction box 54. On the other hand, the suction means 58 such as a pump is sucked from the discharge port 55 of the suction box main body 54 through the exhaust control valve 56 and the exhaust treatment device 57 to discharge mist or dust. In such a system, the pressure inside the suction box 54 is measured by the pressure gauge 60.
Is detected, and the exhaust control valve 56 is controlled according to the detected pressure to adjust the exhaust flow rate with respect to the intake flow rate so that the pressure in the suction box 54 becomes a negative pressure.

On the other hand, in the system shown in FIG. 8, basically, the mist or dust is supplied into the hollow chamber of the suction box 54 only by the suction means 58 such as an exhaust system pump. Inhalation box 5
4 is connected to an inlet pipe 62 for guiding air from the outside through a filter 50, while a test substance such as a chemical solution 52 is connected.
Is made into a thick dust or mist by the air from the compressor 63, the thick dust or mist is supplied in the middle of the introduction pipe 62, and the diluted dust or mist is supplied into the suction box 54, while the suction box 54
The inside of the suction box 54 is evacuated by the suction means 58 such as a pump from the exhaust port 55 of the suction box 58 through the exhaust treatment device 57, whereby the diluted mist or dust is sucked from the supply port 61 of the suction box 54 as described above. It is configured to be retracted into 54. Even when the mist or dust is sucked (supplied) into the suction box 54 only by such exhaust pressure, the inside of the suction box 54 can be slightly negative pressure.

[0016]

In the case of the system as shown in FIG. 7, the exhaust control valve 5 using a computer or the like.
6 must be controlled with high precision, and therefore, there is a problem that the device must be complicated and costly as a whole.

On the other hand, in the case of the system shown in FIG. 8, no particular control is required, but when the flow path resistance of the exhaust treatment device 57 or the filter 50 changes due to clogging or the like, the amount of intake air from the outside decreases. Then, the concentration of mist or dust in the inhalation box 54 may change, which may cause an error in inhalation toxicity evaluation. Further, in the case of the device of FIG. 8, since the mist and dust generated by the pressure of the compressor 63 are diluted by the air from the outside,
It is difficult to supply high-concentration mist or dust into the main body of the inhalation box, and therefore, it is difficult to perform an inhalation toxicity test at high concentration.

The present invention has been made in view of the above circumstances. In particular, the device configuration is not complicated and the cost is not increased, and the concentration of mist or dust in the suction box is changed, or the concentration is high. It is an object of the present invention to provide an inhalation toxicity test device capable of always maintaining a slight negative pressure in the inhalation box with a simple and inexpensive structure without causing difficulty in the inhalation toxicity test. .

[0019]

In order to solve the above-mentioned problems, in the present invention, dust or mist of a test substance is made to flow in the hollow chamber of the suction chamber (chamber), and the animals to be tested are kept in the hollow chamber. In an inhalation toxicity test device adapted to expose at least a part, a feeding means for feeding dust or mist into the hollow chamber at a constant flow rate, and a suction means for sucking and discharging dust or mist from the hollow chamber And a leak hole for drawing in air from the outside is provided at a position downstream of the inhalation site by the test animal in the hollow chamber in the flow direction of dust or mist and upstream of the suction means. .

[0020]

In the inhalation toxicity test apparatus of the present invention, the mist or dust is pushed into the hollow chamber of the suction box at a constant flow rate by the upstream (supply side) pump or other feeding means. On the other hand, if the suction means on the downstream side (exhaust side) is operated so as to suck at a flow rate higher than the flow rate by the feeding means, mist or dust is discharged from the hollow chamber, and at the same time, even in the leak hole, A small amount of air is sucked in from, and the small amount of air is exhausted together with mist or dust. At this time, by setting the suction / exhaust flow rate by the suction means larger than the push-in flow rate by the feeding means, the hollow chamber always has a slight negative pressure. That is, for example, due to the clogging of the exhaust processing means normally provided between the discharge port of the hollow chamber of the suction box and the suction means, the flow path resistance from the feeding means to the suction means slightly changes. Then, even if the flow rate of exhaust gas in the feeding means changes, only the amount of air sucked from the leak hole changes, and the pressure in the hollow chamber is always maintained at a slight negative pressure. Further, since the flow rate of pushing into the hollow chamber by the feeding means is constant and the leak hole is provided on the downstream side of the suction site, the dust and mist can always maintain a constant concentration at the suction site. . Moreover, since the concentration of dust and mist is not diluted, the test substance of high concentration can be inhaled by the test animal.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the overall construction of an inhalation toxicity test device of the present invention.

In FIG. 1, a lower end of the suction box 90 is provided with a supply nozzle 26 for supplying dust or mist containing a test substance into the hollow chamber 35 of the suction box 90.
On the other hand, a discharge port 28 for discharging dust and mist in the hollow chamber 35 is formed at the upper end of the suction box 90.
In the inhalation box 90, the head or the whole body of the animal 32 to be tested is exposed to the hollow chamber 35. The supply nozzle 26 is composed of, for example, a spray nozzle. For supplying air to the supply nozzle 26 from an external air intake 71 through a filter 70, the air is pumped at a constant flow rate. A feeding means 72 such as a compressor is connected via an air supply system passage 73, and a test substance reservoir 74 holding a test substance, for example, a chemical solution or powder, connects a test substance pressure pump 75 and a test substance supply system passage 76. The test substance (chemical liquid or powder) from the test substance reservoir 74 is jetted into the hollow chamber 35 as mist or dust by the air from the feeding means 72. An exhaust treatment device 78 and an exhaust suction means 79 such as a pump are connected to the exhaust port 28 of the suction box 90 through an exhaust system passage 77 in that order.
A leak valve 41 is provided between the exhaust port 28 and the exhaust treatment device 78 in the exhaust system passage 77.
The leak valve 41 is a valve having a leak hole for drawing in (leaking) air from the outside and having an adjustable opening degree. In FIG. 1, 81 is a flow meter for detecting the flow rate of air supplied from the outside, and 82 is a pressure detector for detecting the pressure in the hollow chamber 35 of the suction box 90.

In the embodiment shown in FIG. 1, the leak valve 4 is previously provided.
1, the opening degree of the leak hole is appropriately set, the suction means 79 is operated to suck and exhaust, and at the same time, the feeding means 72.
Is operated to take in air from the outside and at the same time, the test substance pressure pump 75 is operated to supply dust or mist containing the test substance into the hollow chamber 35. At this time, the suction / exhaust flow rate of the suction means 79 is set to be larger than the pushing flow rate of the feeding means 72. As a result, the inside of the hollow chamber 35 is always kept at a negative pressure, and at the same time, a small amount of air is drawn into the exhaust passage 77 from the leak hole. The feeding means 7
The pushing flow rate by 2 is always kept constant.

2 and 3 show a concrete example of an inhalation box (chamber) 90 used in the inhalation toxicity test apparatus of the present invention. The suction box 90 in this example is applied when dust is used.

2 and 3, the suction box main body 20 has a hollow cylindrical shape as a whole, and has an upper portion formed in a conical shape. Specifically, the inhalation box body 20 has a configuration in which a conical upper lid portion 21, a hollow cylindrical body portion 22, and a bottomed short cylindrical bottom portion 23 are vertically and detachably connected. Has been done. The connecting means between them is arbitrary, but in the illustrated example, the flange portion 21 is used.
Packing 24 between A, 22A, 22B and 23A
And the flanges are connected by bolts and nuts 25.

At the center of the lower bottom surface of the suction box body 20, that is, at the center of the lower surface of the bottom portion 23, there is provided a supply nozzle 26 for ejecting dust upward, and the periphery of the position where the nozzle 26 is arranged. A cylindrical guide cylinder 27 that surrounds the space above the nozzle 26 is provided in the. In addition, a discharge hole 23B for discharging the settled dust powder is formed in the peripheral portion of the lower surface of the bottom portion 23. On the other hand, the upper lid 21
A discharge port 28 for sucking and discharging dust is formed at the top of the discharge port 28, and a discharge path 29 is integrally formed above the suction discharge port 28.
A discharge pipe 30 for guiding the dust to the exhaust treatment device and the suction means (suction / exhaust pump) as shown in FIG.
Are connected via the connector 31. The discharge passage 29 is also provided with the leak valve 41 having the above-described leak hole 41A.

Further, a peripheral wall of an intermediate portion of the suction box body 20,
That is, the test animal 3 such as a rat is provided on the peripheral wall of the body 22.
Opening 3 to which holder 34 for holding 2 is attached
3A, 33B, that is, openings 33A, 33B for exposing the head of the animal 32 to be tested are formed in two steps vertically and at intervals. 2 shows the upper opening 33A and the lower opening 33B aligned vertically for simplification of the drawing, but in reality, as shown in FIG. 3, the position of the upper opening 33A is shown. And lower opening 33
It is desirable to shift the position of B from the circumferential direction.

Further, in the hollow chamber 35 in the suction box main body 20, a space body 36 having a shape substantially similar to the shape of the hollow chamber 35 and having a diameter smaller than that of the hollow chamber 35 is the same as the axial center position of the hollow chamber 35. It is arranged so as to be at the axial center position. That is, the occupying body 36 is formed in a hollow shape in which the upper end portion of the bottomed cylindrical body is closed by a conical surface, and the occupying body 36 is a plurality of inwardly projecting portions from the lower peripheral wall of the suction box body 20. It is placed and supported across the tip of the book support arm 37.

The opening 33 in the hollow chamber 35
An acceleration collector plate 38 is horizontally arranged at a position directly above A and 33B. The accelerated collection plate 38 is formed with a large number of small holes 39 that penetrate the plate surface vertically with a uniform distribution density. The acceleration collecting plate 38 has a donut disk shape so as to close the dust flow path between the outer peripheral surface of the space body 36 and the inner peripheral surface of the hollow chamber 35 (inner peripheral surface of the suction box body 20). It is made and is placed and supported by a plurality of support protrusions 40 protruding inward from the inner peripheral wall of the upper end portion of the body portion 22 of the suction box body 20.

When the suction box 90 as described above is used, the dust in which the powder of the solid test substance is dispersed in the gas (usually air) is ejected from the nozzle 26 and the exhaust pipe 30 is used.
The dust ejected from the nozzle 26 is discharged from the discharge port 28 by activating the suction means connected to the exhaust treatment device.
By the negative pressure from the guide cylinder 27, it rises through the space (flow passage) outside the occupying body 36 in the hollow chamber 35, and a small amount of external air from the leak hole 41A of the leak valve 41 in the discharge passage 29. It is drawn to the downstream side. During this time, the coarse particles contained in the dust in the flow path outside the space body 36 settles according to the flow velocity according to Stokes' settling law, and therefore, at the positions of the openings 33A and 33B, that is, at the inhalation site of the test animal, Only particles having a certain size or less, which do not include coarse particles, arrive and are inhaled by the animal 32 to be tested.

The dust passing through the inhalation site of the animal to be tested and reaching the vicinity of the accelerating trap plate 38 has a large number of accelerating trap plates 38 in comparison with the flow passage cross-sectional area of the hollow portion around the occupying body 36. Due to the small total flow passage cross-sectional area of the small holes 39, the flow velocity rapidly increases and passes through each small hole 39 of the accelerated collection plate 38 from below. At this time, due to the rapid increase in the flow velocity as described above, the particles in the space below the acceleration collection plate 38 flow so as to be attracted to each small hole 39, and therefore the dust is collected on the lower surface of the acceleration collection plate 38. The particles are unlikely to adhere. Immediately after exiting upward from each small hole 39 of the acceleration collection plate 38, on the contrary, the flow velocity suddenly decreases and the flow direction diffuses. The particles coarsened by the mixing and coagulation settle down and fall around the small holes 39 on the acceleration collection plate 38, and the remaining fine particles are discharged from the discharge port 28 to the discharge passage 29 and the discharge pipe 30.
Through the exhaust gas treatment device. In addition, the acceleration collection plate 38
At a position higher than the above, coarse particles that have once adhered and aggregated on the inner wall surface of the suction box body 20, the inner surface of the discharge port 28, and the like, also fall onto the acceleration collection plate 38. Therefore, these coarse particles reach the inhalation site of the test animal,
Therefore, it is possible to effectively prevent these coarse particles from being inhaled by the test animal 32.

FIG. 4 shows an example of a suction box 90 when the present invention is applied to a mist. The suction box 90 of FIG. 4 differs from the suction box of FIG. 6 only in that a leak valve 41 having a leak hole 41A is provided in a discharge passage 13A following a discharge port 13 for sucking and discharging mist. The other points are the same as those of the suction box of FIG.

In each of the above-described suction boxes, dust or mist is supplied from below and suction and discharge are carried out from above, but in some cases, mist from above to below like the device shown in FIG. Alternatively, of course, it may be configured to flow dust. Further, although the inhalation boxes of the above-mentioned respective examples are shown as examples in which they are applied to the head exposure method, it goes without saying that the present invention can also be applied to a whole body exposure method inhalation box.

Further, the leak hole 41A is only required to be provided at a position downstream of the inhalation site by the animal under test and upstream of the suction means for exhaust, and in the meantime, the discharge system. Leak holes can be provided at any location in the path. However, in general, an exhaust treatment device is generally provided between the inhalation box and the suction means. In that case, the exhaust treatment device is located downstream of the inhalation site of the animal under test and in front of the exhaust treatment device (upstream). It is desirable to provide a leak hole at the (side) position.

[0035]

As is apparent from the above description, the inhalation toxicity test apparatus of the present invention has a simple and inexpensive structure of providing a leak hole without requiring a particularly complicated control, and always has a hollow inhalation box. The chamber can be maintained at a slight negative pressure, and the concentration of the test substance in the dust or mist in the hollow chamber is unlikely to change, and the inhalation toxicity test can be performed at a high concentration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the entire system of an inhalation toxicity test device of the present invention.

FIG. 2 is a vertical sectional view showing an example of an inhalation box used in the inhalation toxicity test device of the present invention.

3 is a cross-sectional plan view taken along line XX of FIG.

FIG. 4 is a longitudinal sectional view showing another example of an inhalation box used in the inhalation toxicity test device of the present invention.

FIG. 5 is a schematic diagram showing an example of an inhalation box of a conventional inhalation toxicity test device.

FIG. 6 is a vertical sectional view showing an inhalation box of the inhalation toxicity test device previously proposed by the inventor of the present application.

FIG. 7 is a block diagram showing an example of an entire system of a conventional inhalation toxicity test device.

FIG. 8 is a block diagram showing another example of the entire system of a conventional inhalation toxicity test device.

[Explanation of symbols]

 20 Inhalation Box Main Body 26 Supply Nozzle 28 Discharge Port 32 Animal Under Test 33A, 33B Opening 35 Hollow Chamber 41A Leak Hole 72 Feeding Means 79 Suction Means 90 Inhalation Box (Chamber)

Claims (1)

[Scope of utility model registration request] 1. An inhalation toxicity test apparatus in which dust or mist of a test substance is caused to flow into a hollow chamber of an inhalation box and at least a part of an animal under test is exposed in the hollow chamber, wherein a constant flow rate is provided in the hollow chamber. A feeding means for feeding dust or mist, and a suction means for sucking and discharging dust or mist from the hollow chamber,
In addition, the inhalation toxicity is characterized in that a leak hole for drawing in air from the outside is provided at a position downstream of the inhalation site of the test animal in the hollow chamber in the flow direction of dust or mist and upstream of the suction means. Test equipment.